Black''''s veterinary dictionary 21st edition - R doc

R R Factor (see PLASMIDS) Rabbit Fur Mite This may be picked up by dogs and rabbitkeepers, and cause intense irritation (See CHEYLETIELLA PARASITIVORAX.) Rabbit Haemorrhagic Disease Rabbit haemorrhagic disease is widespread throughout the UK and the rest of Europe The disease, caused by a calicivirus, originated in China and may have been imported into Europe in rabbit meat Cases are not known in rabbits under months, at which age liver metabolism changes This makes it a serious problem for breeders when a doe dies, leaving an orphan litter Clinical signs are often transient: difficulty in breathing, or a short squeal followed immediately by the rabbit falling over, is often accompanied by sudden death Animals surviving the acute stage develop jaundice and die after a few weeks Haemorrhage from the nostrils and/or anus may be seen Prevention is by vaccination Rabbit Rings The British Rabbit Council issues 100,000 metal rings each year in the UK to members to use in identifying rabbits, but advises that the rings should be removed from rabbits sold or given away as pets ‘Injury can occur if bedding material becomes trapped between ring and leg,’ or if the ring has become – with the rabbit’s growth – too tight, with the risk of causing necrosis Should that occur, surgical intervention or euthanasia will be needed California, and the Dutch rabbit (See also PETS, CHILDREN‘S AND EXOTIC.) Handling When lifting a rabbit, a fold of skin over the shoulder and back should be grasped with one hand, while the other supports the rump A rabbit should not be lifted by its ears Struggling while being inexpertly handled can lead to fractures of limbs A startled rabbit may leap and fracture the spine Diseases include APPENDICITIS; ATROPHIC RHINITIS; COCCIDIOSIS; HYDROMETRA (the accumulation of watery fluid in the uterus); IMPACTION of colon or stomach (often the result of insufficient hay being provided); LISTERIOSIS; MASTITIS; METRITIS; MYXOMATOSIS; PASTEURELLOSIS; PNEUMONIA; RABBIT HAEMORRHAGIC DISEASE; ‘RABBIT SYPHILIS’; SALMONELLOSIS; SCHMORL’S DISEASE; TOXOPLASMOSIS; TUBERCULOSIS; TYZZER’S DISEASE; YERSINIOSIS Pasteurella multocida causes a pneumonia which may be acute and fatal in rabbits under 12 weeks old It may cause also middle-ear disease with a loss of balance, circling, and head held to one side, epiphora, and also ‘snuffles’ in which there is a discharge from eyes and nose and sneezing Rabbits act as hosts of the liver-fluke of sheep, and of the cystic stages of some tape-worms, e.g Taenia pisiformis, T serialis Rabbits have been used experimentally as incubators for sheep’s eggs A hermaphrodite rabbit served several females and sired more than 250 young of both sexes In the next breeding season the rabbit, which was housed in isolation, became pregnant and delivered healthy young of both sexes Pregnancy diagnosis An ELISA test is available for this purpose It can also differentiate between pseudo-pregnancy and pregnancy, and detect rabbits about to ovulate ‘Rabbit Syphilis’ ‘Rabbit syphilis’ is caused by a spirochaete, Treponema cuniculi (which does not affect humans) It is a venereal disease characterised by the appearance of nodules and superficial ulcers covered with thin, moist, scaly crusts and oedematous swellings of the surrounding tissues mainly in the region of the genitalia (hence the colloquial name, ‘vent disease’) and also sometimes in the region of the nose Rabbits Breeds of domesticated rabbits used for table purposes include the New Zealand white, the Anaesthesia A wide range of anaesthetics is suitable for use in rabbits Halothane and other inhalation anaesthetics are suitable and convenient to administer Premedication with atropine (50 micrograms per kg by hypodermic or intramuscular injection) or acepromazine (1 mg per kg intramuscularly) is advisable half an hour earlier Alfaxalone/alfadolone (Saffan) is one of several injectable anaesthetics recommended for surgery Oxygen should be ready to hand The Veterinary Formulary, published by the BVA/Royal Pharmaceutical Society, gives 582 Rabies comprehensive details of anaesthetics and analgesics suitable for rabbits and small rodents to DEFRA or to the police Bitten persons should seek medical advice immediately Rabies Cause A Lyssavirus (one of the Rhabdovirus The Latin word for madness, it is a specific inoculable contagious disease of virtually all mammals, including man; and occasionally it occurs in birds, e.g domestic poultry and vultures It is characterised by nervous derangement, often by a change in temperament, with paralysis occurring in the final – and sometimes in the intermediate – stages Foxes and cattle are both highly susceptible to infection Rabies occurs in all continents with the exception of Australasia and Antarctica In Turkey, dogs remain the principal vectors; in a few countries in Europe cats attack more people than dogs In Asia and South America dogs are still the most important vectors, but in many countries wild animals provide a reservoir of infection, and infect dogs and cats and farm animals – which in turn may infect man, who is an incidental host of the disease (See table of vectors.) group) When it is injected into the tissues, either naturally (from a bite) or artificially, the virus passes along the nerves and reaches the central nervous system The time elapsing between infection and onset of symptoms varies greatly with the location of the bite, its severity, and – no doubt – the quantity of virus in the saliva In the most rapidly developing cases the symptoms may be shown as early as the 9th day after being bitten, and at the other extreme, cases have appeared several months after the incident It is owing to this fact that the 6-months period of quarantine insisted upon in Britain is something of a compromise The average incubation periods in dogs, sheep, and swine are from 15 to 60 days; in horses and cattle, from 30 to 80 days In young animals the period of incubation is shorter than in adults Public health Rabies is virtually always fatal in R the human being, and there is danger not only from being bitten by rabid animals, but also from contamination by their saliva of wounds, cut fingers, eyes, etc Scratches may convey infection as well as bites People have died from rabies following attacks by rabid dogs, cats, foxes, wolves, badgers, skunks, racoons, mongooses, bats, rodents, etc Pet animals, such as rabbits, may be bitten by rabid animals and themselves become rabid; and it has sometimes happened that wild or exotic animals (originating in countries where rabies is endemic) were bought as pets while in the incubation stage of rabies, with unfortunate results In the UK as in most other countries, rabies is a NOTIFIABLE DISEASE, and must be reported Rabies in wild animals – principal vectors in various regions Europe Asia North America Central America South America and Trinidad Foxes, roe-deer, badgers, martens Wolves, jackals, bats, mongooses Foxes, skunks, coyotes, bats Bats Vampire bats Signs Dog There are distinct forms of rabies in the dog – the ‘furious’ and the ‘dumb’; but these are in reality stages only It is customary to consider stages of typical symptoms (1) Melancholy The prodromal dull stage is often not noticed, or, if it is, only scant attention is paid to it The habits of the dog change It becomes morose and sulky, indifferent to authority, disregards its usual playthings or companions, shows a tendency to hide in dark corners, and may appear itchy or irritable as regards its skin Noisy, boisterous animals become quiet and dull, while animals that are normally of a gentle, quiet disposition may become excitable After or days of such behaviour the next stage is reached (2) Excitement The symptoms described above become exaggerated, and there is a tendency towards violence The dog pays no attention to either cajoling or threatening It becomes easily excited and very uncertain in its behaviour Food is either disregarded completely or eaten with haste Vomiting is a not uncommon symptom A fear of water is not a symptom to expect in the rabid dog, which will often drink or attempt to so even when partly paralysed After a time the appetite becomes deranged The dog refuses its ordinary food, but eats straw, stones, wood, coal, carpet, pieces of sacking, etc., with great avidity If the animal is shut up in a kennel, it persists continually in its efforts to escape Should it be released or should it escape, it almost invariably runs away Rabies from home It may wander for long distances In its travels it bites and snaps at objects which it encounters, real or imaginary, animate or inanimate Some rabid dogs bite several people The tone of voice is altered The face has a vacant stare, the eyes are fixed and expressionless, and the pupils are dilated This stage lasts from to days, unless the dog’s strength gives out sooner, and the next stage appears (3) Paralysis The characteristics of the last stage in the train of symptoms of rabies are those of paralysis, especially of the lower jaw and the hindquarters The dog begins to stagger in its gait, and finally falls It may manage to regain its feet when stimulated, but soon falls again The lower jaw drops, the tongue lolls out of the mouth, and there is great salivation The muscles of the throat and larynx are soon involved in the progressive paralysis The dumb form of rabies consists of this paralytic stage – the stage of excitation having been omitted The dumb form is the more common in the dog: barking ceases – hence the name Vomiting may suggest merely a digestive upset Protrusion of the nictitating membrane partly across the eye, together with a dropped jaw, i.e partly opened mouth which can be closed by gently raising the lower jaw by means of a stick, are highly suggestive of rabies In parts of Africa and Asia, the classical form of rabies in dogs (described above) is replaced by a form called (in Africa) ‘OULOU FATO’ Cat In this animal the furious form is more common than in the dog The aggressive stage is most marked, the cat attacking other animals and man with great vigour, and attempting to injure their faces with teeth or claws Sometimes the rabid cat will at first show extra affection The course of the disease is usually shorter than in the dog It is worth mentioning that occasionally dogs and cats die from rabies without any observed symptoms They may be found dead or dying It is not unknown for a cat to be found lying in a field or garden unable to walk but still able to bite Cattle These animals are usually affected through having been bitten by a rabid fox or dog The stage of excitement is short and the dumb stage most evident Affected cattle behave in an unusual manner; they may stamp or bellow, salivate from the mouth, break loose, and may much damage Rumination and milk production cease, muscular quiverings are seen, sexual excitement is noticed, and there is 583 a great loss of condition Exhaustion soon follows and paralysis sets in Death occurs within to days or more after the commencement of the condition Rabies may be mistaken for hypomagnesaemia, milk fever, botulism, anaplasmosis, listeriosis, lead poisoning, choking, etc In Central and South America, cattle are infected with rabies by vampire bats, and may show long streaks of blood on their shoulders, necks and backs Sheep, goats and swine The sheep and the goat are affected in a manner similar to cattle, but the stage of excitement is shorter or absent, and the dumb paralytic stage is more often noticed Pigs become excitable; they may squeal and show muscular spasms before paralysis ensues Horse The furious form is common but the animal may appear calm between bouts of aggressiveness Dumb forms also occur and may be mistaken for colic, paresis or encephalitis from other causes Signs may include a facial twitch, biting of woodwork or self-mutilation, head-tossing, frequent whinnying, abnormal posture, apparent lameness, ataxia, paralysis of hindquarters The horse may continue to eat and drink until shortly before death The tone of voice may be altered Diagnosis The routine examination for Negri bodies has now in most countries been superseded by the fluorescent antibody test, with confirmation by mouse inoculation if necessary (If a dog which bit someone is still alive after 10 days, it cannot be assumed that the dog is not rabid.) Differentiation between laboratory and street rabies virus, between rabies vaccine virus and street virus, and between rabies virus and rabies-like viruses (e.g Mokola, Lagos bat, and Duvenhage viruses) is possible by laboratory tests based on differentiation of monoclonal antibodies Prevention Prevention of the disease in man and animals stems from the research of Louis Pasteur in the 1880s He discovered the process of attenuation, by which the virulence of a micro-organism is reduced but not its ability to produce antibodies against disease Pasteur achieved this by infecting rabbits with rabies from a dog Although this was fatal to the rabbits, dogs survived infection with the rabbit virus Tissue from the spinal cord of an infected rabbit was then used to prepare a vaccine R 584 Rabies His triumph came in 1885 when the vaccine saved the lives of badly bitten boys In the intervening years many modifications have been made, and new techniques developed, to make rabies vaccines which would be safe and free from dangerous side-effects, and so could be used to immunise people and animals against rabies (‘pre-exposure’ – vaccination), as well as provide ‘post-exposure’ treatment of those bitten by rabid animals The table shows examples of vaccines prepared from tissue culture cells The last one, the Merieux, was developed by the Merieux Institute of France using a technique pioneered at the Wistar Institute of Philadelphia Only ml doses are required, and injections (apart from any booster doses) (See also VERO CELLS.) In the UK, vaccines approved for use in dogs and cats: Rabisin rabies vaccine (Merial) containing inactivated GS-57 Wistar virus strain; and Nobivac Rabies (Intervet) prepared from virus grown on cell-line tissue culture Mass vaccination of dogs is carried out in many countries as a control measure; and in Central and South America, cattle on ranches are vaccinated against vampire-bat-transmitted rabies In France and other countries of Europe, hundreds of thousands of cattle are vaccinated against rabies (often a combined rabies/foot-and-mouth disease inoculation) It must be remembered, however, that no vaccines are 100 per cent effective, that certificates of vaccination can be forged, and that consequently it is still essential to control the import of animals, whether vaccinated or not, and to enforce quarantine measures where appropriate R Control of rabies in Britain From 1902 until 1918, no cases occurred in the British Isles; but in that year infected dogs were smuggled from the Continent, and the disease obtained a fresh hold for a period of little more than years Britain had been free since then, but in 1969 a dog released from quarantine 10 days earlier showed symptoms of rabies and bit people at Camberley, Surrey; a 2nd case occurred in 1970 In 1965 there was a case in a recently imported leopard in quarantine at Edinburgh Zoo In Britain, in 1969, the danger of allowing the importation of rabies-susceptible exotic animals, for sale as pets or for research, was officially recognised, and the quarantine regulations amended to include monkeys, mongooses, etc Following strong pressure to replace quarantine for pet dogs with a vaccination/identification policy, a government committee was set up in 1997 to examine the issue The committee recommended that a strict scheme of medical examination, rabies vaccination and veterinary certification should replace the compulsory quarantine regulations for dogs and cats The recommendation was accepted and an arrangement introduced in 2000 under which dogs and cats may travel to and from the UK and specified countries without quarantine under the PET TRAVEL SCHEME (See also IMPORTING/EXPORTING ANIMALS.) Other points to note: (1) the saliva is sometimes infective before symptoms of rabies appear – a hazard for a person licked; (2) farmers have died through mistaking rabies for ‘choking’ and, with abraded fingers, examining their cow’s mouths; (3) non-typical cases of rabies are not uncommon; (4) a dog may bite a small child or household pet and promptly run away – rabies not being suspected, though running away is in itself a canine symptom; (5) the virus may be present in semen, as well as in milk, tears, faeces, and urine; and (6) subclinical rabies, and a ‘carrier’ state, have long been recognised in Africa (see ‘OULOU FATO’) and in Asia Vaccination of foxes has been an outstanding success in controlling the disease in Western Europe Currently Britain, Andorra, Ireland, Examples of rabies vaccines prepared from tissue culture cells Live virus: ERA HEP-Flury Inactivated: Fixed Cells used: Pig kidney Dog kidney Cats, dogs, cattle and other animals Cats, dogs, and cattle Hamster kidney Cats, dogs, cattle and other animals Hamster embryo Cats, dogs, horses, cattle and sheep Racehorses Italy, Netherlands, Norway, Sweden, Denmark, Greece, Spain and Portugal are all rabies-free There are still black spots in Germany, while there are enzootic areas in Poland and Turkey The oral vaccine is genetically engineered on vaccinia virus so that the antigen to rabies is absorbed from the intestine The vaccine is put into fish-flavoured capsules scattered from helicopters In the areas so treated, up to 93 per cent of foxes, stoats, weasels, polecats and badgers caught and bloodsampled have been found to have taken up the vaccine Rabies (Control) Order 1974 This gives powers to deal with an outbreak of rabies outside quarantine premises In a declared infected area, an order may be made for the destruction of foxes and other wild mammals, and for access to land for this purpose Fences or other types of barrier may be erected to restrict movement of animals into or out of an area while such destruction is in progress Orders may be made for compulsory vaccination, confinement, and control of domestic animals, including strays Anyone knowing or suspecting that an animal has rabies must notify that suspicion to the police Deaths of animals in an infected area must also be notified, and the authorities can take over ownership of carcases and determine the means of their disposal This is because it is essential to confirm a diagnosis of rabies, so that precautions can be taken concerning in-contact animals and human beings The order can override a dogowner’s reluctance or refusal to part with the body of a dead pet or working dog The Rabies (Importation of Mammals) Order 1974 prohibits the landing of susceptible mammals in Britain unless from Ireland, Isle of Man, or the Channel Islands Any animal brought in from elsewhere has to undergo a period of quarantine Imported animals are vaccinated while in quarantine as a precaution against a quarantined animal developing the disease Those animals not a threat to human health (ruminants, pigs and horses) not go into quarantine for rabies but may be quarantined for other diseases Control under the Order is exercised on the transport of imported susceptible animals within Britain If an animal is landed at a port or airport not authorised to receive such animals, that constitutes an illegal landing even if the circumstances are outside anyone’s control (e.g if an airport is fogbound) Under a 1984 amendment order, animals which have not been in contact with another 585 animal (e.g have been on an oil rig) are permitted to be landed in Britain A similar relaxation applies to animals belonging to the police, Customs & Excise and H.M Forces, if the animal has been abroad but under the constant control of a trained handler while outside Britain (See also PET TRAVEL SCHEME (PETS).) Rabies-Related Viruses These include Duvenhage virus, the cause in fruit-eating bats of a disease very similar to rabies; the Mokola virus, which has been isolated from shrews, and causes nervous symptoms in man; the Lagos bat virus; the Nigerian horse virus and Lyssa virus Raccoons Raccoons are, in Canada and the USA, among the wildlife creatures which sometimes transmit rabies A dog bitten by a (non-rabid) raccoon may become paralysed in all limbs (quadriplegia) Racehorses Every year between 1400 and 1600 thoroughbred mares go to stud in the UK About 67 per cent of them foal successfully, and for every 1000 mares covered, 270 or so of the resulting progeny finally appear on the racecourse Temperament, unsoundness, or sale abroad account for the non-appearance of more in the UK An epidemiological study of wastage among racehorses has been conducted among stables, of which were in Newmarket The basis of the survey was the inability of horses to take part in cantering exercise as a result of injury or disease The greatest number of days lost to training was caused by lameness (67.5 per cent) and respiratory problems (20.5 per cent) Conditions of the foot (19 per cent), muscle (18 per cent), carpus (14 per cent), fetlock joints (14 per cent), tendons (10 per cent) and sore shins (9 per cent) were the major reasons for training days being lost in 198 cases in which a positive diagnosis of the site of lameness was made Pulmonary haemorrhage In horses which show blood at their nostrils after exercise such as racing, the blood does not come from the nasal cavity but from the lungs Endoscopic examination showed an incidence of 42 per cent in a group of horses with only 15 per cent showing blood at the nostrils Affected horses might appear distressed, with dilated pupils Exercise-induced pulmonary haemorrhage was observed in 23 of 49 endoscopic examinations after high-speed training, in of 37 examinations after cantering, and in of 17 after R 586 Rachitis walking or trotting; it was not possible to predict its occurrence Mucoid or mucopurulent exudate was observed in 60 of 118 examinations and the amount increased after exercise Pulmonary haemorrhage was diagnosed by endoscopic examination in 255 2-year-old quarterhorses after racing Only (3.5 per cent) of the animals had visible epistaxis Fatal pulmonary haemorrhage occurred in a racehorse which panicked as the aircraft in which it was travelling landed (See HORSES, BREEDS OF; HORSES; EXERCISING HORSES; etc.) Rachitis (see RICKETS) Radial Paralysis (‘Dropped Elbow’) Radial paralysis (‘dropped elbow’) is commonest in horses and dogs, though it may be seen in any animal Causes Probably the majority of cases are due to a fracture of the 1st rib on the same side of the body, the broken ends of the rib lacerating the nerve-fibres as they pass the rib, or pressing against them In other cases the origin of the paralysis seems to be situated in the end-plates of the nerve-fibres where they are distributed to the muscles, and in some cases a neuritis involving the radial nerve, or a tumour pressing upon it at some part of its course, is responsible for producing the condition R Signs In a typical case the horse stands with the elbow dropped lower than normally, and with the knee, elbow, and fetlock joints flexed Little or no pain is felt, unless there is a fractured rib, or some inflammatory condition which has caused the paralysis The limb is held in the position assumed at the commencement of a stride, but the animal is incapable of advancing it far in front of the sound limb No weight is borne upon the leg, the muscles are flaccid and soft, and if the horse is made to move forward either it does so by hopping off and on to the sound fore-limb, or it may fall forwards If the hand be forcibly pressed against the knee, so that the limb is restored to its natural upright position, the horse is able to bear weight upon it and may lift the other limb from the ground, but as soon as the pressure is released, the joints fall forward again Sometimes the toe is rested upon the ground, but at other times the horse stands with the wall of the foot in contact with the ground In cases that are not so severe, the flat of the foot may rest on the ground, and the limb can be advanced forwards to a considerable extent Treatment The majority of such cases as these will recover in a few weeks Patience on the part of the owner is essential Radiation, Exposure to The 1986 Chernobyl nuclear power-station disaster in the former USSR led to controls being imposed on the movement and slaughter of sheep in parts of Scotland, Cumbria, and Wales, after between 1000 and 4000 Becquerels/kg of caesium-137 had been detected in lambs Similar controls were applied in other countries affected by the fallout The ban temporarily affected about million sheep and lambs in some 500 flocks The Atomic Energy Authority stated that 10,000 Bq/kg represents a health risk However, the contamination figures exceeded, in cases, the internationally recommended action levels for radiocaesium of 1000 Bq/kg The highest figure was 4000 ‘Although the physical half-life of radiocaesium is 30 years, its biological half-life is much shorter In an adult animal, the half-life is estimated at between 30 and 100 days, but for lamb it would be between 25 and 50 days.’ (MAFF) (See also RADIOACTIVE IODINE; RADIOACTIVE STRONTIUM.) Annual human exposure Of the average UK citizen’s annual exposure to radioactive discharges, only 0.1 per cent comes from the nuclear power industry, according to the Radiological Protection Board For radiation exposure associated with veterinary practice, see RADIOISOTOPES and X-RAYS Carbon-14 is among internal sources of natural radiation, and is present in the human body to the extent of about 2000 Bq Radiation, Protection against Regulations governing the use of X-ray equipment, and the precautions to be taken by those handling it, are very strict Details are given in the Health and Safety at Work Act (See under X-RAYS.) A concise guide to the Health and Safety at Work Act 1974 can be obtained from HSE Books, PO Box 1999, Sudbury, Suffolk COI0 6FS Radiation Sickness Dogs exposed to radiation following a nuclear explosion will vomit as a result of gastroenteritis, become dull and lose their appetite This Radio ‘Pills’ (Telemetering Capsules) may return after a day or two, but leucopenia develops, and may be followed by haemorrhage or septicaemia Radioactive Caesium High levels of caesium 137 were found in areas of Wales and Scotland following the nuclear power-station explosion at Chernobyl in 1986 Certain flocks of sheep were affected by the fall-out and the meat declared unfit for human consumption for some time Antidote A ferric-cyano-ferrate (AFCF), in the form of a dark blue powder, can bind radiocaesium both in vitro and in the gastrointestinal tract of animals very effectively, preventing the isotope from being absorbed and secreted into the milk or transferred to the meat of cows, etc The addition of only g AFCF per day to the diet of lactating cows reduced the radiocaesium content of their milk by between 80 and 90 per cent, and of their meat by 78 per cent The radiocaesium content of the meat from sheep fed g AFCF per day or of calves or pigs fed g AFCF per day was reduced by approximately 90 per cent The compound was given official clearance as a feed additive against radiocaesium in Germany Radioactive Discharges Of the average UK citizen’s annual exposure, only 0.1 per cent comes from the nuclear power industry, according to the Radiological Protection Board Around 90 per cent comes from natural sources, principally radon gas released from building materials For radiation associated with veterinary practice, see RADIOISOTOPES and X-RAYS Radioactive Fall-Out Radioactive fall-out, following the explosion of nuclear bombs, etc., or accidents at atomic plant, may be dangerous to farm livestock on account of the radioactive iodine and strontium released After an accident at Windscale, radioactive iodine alone contaminated pasture in the area (See also RADIATION, EXPOSURE TO; RADIATION SICKNESS; RADIOACTIVE IODINE.) Radioactive Iodine Cattle grazing pasture contaminated by fall-out pick up 10 times as much radioactive iodine as people in the same locality, according to American reports Much is excreted in the milk, and much concentrated in the thyroid glands Feeding-stuffs or pasture contaminated by fall-out containing radioactive iodine and 587 strontium may give rise to illness in cattle Digestive organs may be damaged, changes in the blood occur, and deaths follow within a month or so, after a period of dullness and scouring (See RADIOACTIVE STRONTIUM.) Radioactive Strontium Whereas the half-life of radioactive iodine is a matter of days, that of strontium is 30 years Following the grazing of contaminated pasture or the eating of other contaminated feed, radioactive strontium is excreted in the milk, but much of it enters the bones and is liable to set up cancer many years afterwards The UK average ratio of strontium-90 to calcium in milk was 2.8 picocuries per gram of calcium in 1975, compared with 3.3 picocuries per gram in the previous year; this result is about one-tenth of the maximum reached in 1964 The average concentration of caesium137 (7 picocuries/litre) was about four-fifths of the value in 1974 and less than one-twentieth of the 1964 maximum (AFRC.) Radio-Frequency Treatment (see under CANCER – Treatment) Radiography (see under X-RAYS) Radioimmune Assay A method of measuring antigen or antibody concentration by means of radioactively labelled reagents (see RADIOISOTOPES) Radioisotopes A radioisotope is a form of an element that undergoes decay while emitting radiation Artificial radioisotopes (radiopharmaceuticals) are widely used in diagnosis and in human medicine Nuclear medicine involves the use of unsealed radioisotopes for diagnosis and therapy For example, in bone scanning, the most commonly used radiopharmaceutical is methylene diphosphonate, labelled with Technetium 99 mm (Tc-99) With a half-life of only hours, high doses can be given for a low radiation burden, permitting high resolution pictures to be obtained Radio ‘Pills’ (Telemetering Capsules) Radio ‘pills’ (telemetering capsules) have been developed for research purposes A radio transmitter, the size of an ordinary drug capsule, can give information concerning pressure, temperature or pH within an organ R 588 Radius Radius The inner of the bones of the fore-limb In the horse and ox particularly, the radius forms the main bone of this part, the ulna being much smaller and not taking part in weightbearing (See BONE.) Radon A colourless gas produced by the disintegration of radium It is found naturally in low concentrations in certain areas, e.g parts of Cornwall, where it has given rise to public-health concerns (see under RADIOACTIVE) Ragdoll A breed of cat originating in the USA, so called because it tends to ‘flop’ if carried They have a high pain threshold and, if involved in a fight, could continue long after a normal cat would have stopped As a result, it could sustain serious injuries even if it won the fight Ragwort Poisoning R Ragwort poisoning causes losses among cattle and sheep in Great Britain, Canada, and New Zealand It is the cause of the ‘Pictou cattle disease of Canada’, and of ‘Molteno cattle disease’ in South Africa The plant (Senecio jacobaea, or sp.) is very often fed off by sheep when it becomes too plentiful in grass land In the UK fatal poisoning has followed the giving of hay contaminated with ragwort – death occurring many weeks after the last mouthful The death of 28 head of cattle was caused to months after feeding ragwort-contaminated silage Acute ragwort poisoning may also occur, causing death in to 10 days with symptoms of dullness, abdominal pain, and sometimes jaundice Ragwort contains PYRROLIZIDENE ALKALOIDS, which produce cirrhosis of the liver, inflammation of the 4th stomach, and other lesions In grazing horses, ragwort will be eaten only if other food is not available but may be ingested in hay or silage In the UK after a mild, damp winter, when the plant grows earlier in the year than usual, and is sprouting among the grasses, horses may eat it Chronic liver damage may result, with acute signs apparent when the cirrhosis becomes advanced Milk from a cow which has eaten ragwort may be dangerous to children, causing liver damage Signs include loss of appetite and of condition, constipation, sometimes jaundice Cattle may strain and later become excited and violent; horses may become drowsy, with a staggering gait Secondary gastric impaction and rupture in horses has been reported Treatment There is no specific antidote, but methionine has been reported to be helpful (See LIVER, DISEASES OF.) Diagnosis A liver biopsy may be helpful in the diagnosis of chronic ragwort poisoning in horses – ‘probably the most common cause of chronic hepatic pathology in horses in the UK’ ‘Rain Scald’ An old name for Dermatophilus infection in horses subjected to prolonged wetting Lesions occur on withers, shoulders, and rump For appearance of the lesions, see under GREASY HEEL, and DERMATOPHILUS Rainfall Rainfall may influence outbreaks of HYPOMAGNESAEMIA; BLOAT; FOOT-AND-MOUTH DISEASE Rales (Moist Sounds) Rales (moist sounds) are sounds heard by auscultation of the chest during various diseases They are divided into main classes: (1) crepitant or vesicular rales, which are heard in the 1st stages of pneumonia, and are sharp, fine, crackling noises noticed during inspiration only; and (2) mucous rales, which are heard during expiration as well as during inspiration and may be described as bubbling or gurgling sounds Ram Epididymitis This is a disease of economic importance in most of the sheep-farming areas of the world, including Australia and Mediterranean Europe, but not the UK The cause is Brucella ovis Diagnosis by clinical means (palpation, mainly) is not very satisfactory Laboratory tests to confirm the organism confirm the diagnosis Vaccination and culling are methods of control, but vaccination is not free from problems Contagious epididymitis is a NOTIFIABLE DISEASE throughout the EU Rancidity Rancidity of cod-liver oil or other fish oils, etc., can be extremely dangerous Rancid mash may bring about deficiencies of vitamins A, D, and E, with acute digestive disorders and death in chicks Growing and adult birds may also suffer losses from this cause; with osteomalacia, and decreased egg production (See also under VITAMIN E.) Rations for Livestock 589 Rangoon Beans Rarefaction of Bone (see JAVA BEAN POISONING) A decrease in the mineral content Ranula Rat and Mouse Poisons Ranula is a swelling which sometimes appears below the free portion of the dog’s tongue It is caused by a collection of saliva in one of the small ducts that carry saliva from the glands below the tongue, or further back, into the mouth, and when of some size a ranula may cause considerable interference with feeding It is treated by incision or excision, and is usually not serious (see under RODENTS) This is a disease recognised in man and caused, following the bite of a rat (or, sometimes, dog, cat, mouse, weasel, or squirrel), by infection with Spirillum minus or Streptobacillus moniliformis In addition to fever there may be an extensive rash Rape Poisoning Rations for Livestock Rape poisoning occurs in animals which are not given hay or other food in addition to rape Poisoning can be extremely serious, especially in sheep Signs include dullness, red-coloured urine, and blindness In one outbreak reported by the Reading VI Centre, 36 out of 360 sheep died from rape poisoning A form of light sensitisation called ‘rape scald’ occurs in sheep on rape Swelling of the head occurs, there is irritation leading to rubbing, the ears may suffer damage Jaundice may occur Rapeseed Cake A compressed ‘cake’ of rapeseed is used as a cattle feed The oil is first removed and the cake may be processed to remove any toxicity Rapeseed Oil This has been shown experimentally to be toxic to the hearts of rats The degree of toxicity varies according to the erucic acid content of the oil, and perhaps to closely related monoethylenic acids (e.g cetoleic and nervonic) It is apparently the breakdown of erucic acid in the myocardium and skeletal muscles which produces the damaging effects The use of the oil in margarine manufacture and as a substitute for more expensive olive oil has led to anxiety over the effects on the human heart Rapeseed meal fed to poultry may depress growth and egg yield, and cause hypertrophy of the thyroid gland, liver haemorrhage, abnormalities of the skeleton, and a fishy taint in the eggs The liver haemorrhages resemble those associated with the ‘fatty liver/haemorrhagic syndrome’ Rapeseeds of low toxicity, such as the Canadian variety canola, have now been bred Raphe Raphe means a ridge or furrow between the halves of an organ Rat-Bite Fever Dairy cattle Winter rationing The home-grown foods available naturally vary from farm to farm Farmmixed rations often make good use of barley Proprietary compound feeding-stuffs are well balanced and formulated to contain all necessary ingredients such as vitamins, trace elements, etc., and are nowadays extensively used Proprietary barley balancers and straw balancers are also much used (See also under WINTER DIET.) Rations: theoretical basis for calculation Traditionally, it is customary to regard the ration as being composed of parts: (1) the ‘maintenance’ part, which provides the material for all vital activities and makes good the normal wear and tear of the body without causing increase or decrease in liveweight; and (2) the ‘production’ part, which supplies the materials used for increase in body size, fat production, growth of the fetus, and milk production ADAS Advisory Paper No 11, Nutrient Allowances and Composition of Feeding-Stuffs for Ruminants, contains valuable sets of information: firstly, what different classes and weights of ruminant stock need for maintenance and production; and secondly, the analyses of a wide variety of feeds Maintenance and 4.5 litre (1 gallon) rations for cows of Friesian breed or similar: kg (lb) (a) Hay (18) Brewer’s grains 4.5 (10) Dried sugar beet pulp 1.8 (4) (b) Hay (18) Dried sugar beet pulp 1.8 (4) Silage 23 (50) with parlour-fed concentrates, 1.5 kg (3H lb) per 4.5 litres (1 gallon), for both (a) and (b) Maintenance plus litres (2 gallons): Ryegrass/lucerne haylage ad lib R 590 Rations for Livestock Brewer’s grains plus minerals kg (15 lb) with every 1.8 kg (4 lb) hammer-milled maize fed in parlour for every additional 4.5 litres (1 gallon) Summer rationing Grass is the standard summer food for cattle On a good, well-managed pasture – where over-stocking is avoided – young, leafy grass will supply enough protein for high yielders, but they will require additional carbohydrate This may be supplied in the form of cereals, e.g 1.8 kg (4 lb) for each 4.5 litres (1 gallon) of milk over about 20 litres (4H gallons) produced per day It has been recommended that in April, cows grazing young, leafy grass 10 to 15 cm (4 to inches) high for hours daily, should receive kg (7 lb) hay and cereals (plus a mineral mixture) at the rate of 1.8 kg (4 lb) for each 4.5 litres (1 gallon) over 13.5 litres (3 gallons) In May, with unrestricted grazing of grass 20 or 25 cm (8 or 10 inches) long at the pre-flowering stage, the hay is discontinued; the cereal ration remaining as before In June and July, with grass at the flowering stage, the cows receive balanced concentrates for yields over 11 litres (21⁄2 gallons) (June), then over litres (2 gallons) In August, grazing aftermath (or green fodder during a drought), the cows receive concentrates for each 4.5 litres (1 gallon) over the first 4.5 litres (1 gallon) In September, with young aftermath or maiden seeds, there is a hay ration of kg (7 lb) (or 13 kg (28 lb) kale) plus concentrates for yields over litres (2 gallons) per day More sophisticated calculations for feed requirements are based on the metabolisable energy requirements of specific herds or even animals Calculations take into account the amount of energy required for maintaining condition; the quantity of milk produced; and the stage of pregnancy For growing cattle, rations are calculated based on the maintenance requirement plus the daily liveweight gain Beef cattle (see table re suckler cows, and under BEEF) Calves (see CALF-REARING) Pigs Creep feed Barley meal Flaked maize White fish-meal Wheatings Per cent 40 30 15 15 Rations for suckler cows Autumn calvers BlueHereford Grey × Friesian (kg per day) R Calving to mating Grass silage (25% DM, 60D) Mineralised barley Hay (57D) 35% protein concentrate Mating to turnout Grass silage Mineralised barley Hay Protein concentrate During this period cows can lose about 0.5 kg per day so that conditionfalls by about / score to turnout 27 1.25 1.75 27 10 1.75 25 0.5 0.75 27 0.5 0.75 grazing grazing Spring calvers Blue- Hereford × Grey Friesian (kg per day) Mid-pregnancy to calving Grass silage Mineralised barley Hay Protein concentrate Barley straw Protein concentrate 20 0.5 0.5 1.5 20 0.5 0.5 1.75 Calving to turnout Grass silage Mineralised barley Hay Protein concentrate Barley straw Protein concentrate 25 2.75 27 8.5 3.25 grazing grazing Mid-pregnancy to calving 606 Ring Vaccination joint (i.e between the long and short pastern bones) is the seat of the disease; (2) low ringbone, where the deposit occurs round the coffin-joint, between the short pastern bone and the coffin-bone; and (3) false ring-bone, where the enlargement occurs upon the shaft of one of the bones and does not involve the edges of a joint surface (though it may so later) From the point of view of etymology it would appear that the term ‘ring-bone’ should be restricted to conditions in which a partial or complete ring of bone is formed round one or other of the joints, and that all other bony enlargements affecting the surface of the shaft of the bones, but not involving the edges of the joint surfaces, should be called exostoses Difficulty arises, however, when examining a horse’s foot, in determining exactly whether the joint surfaces are affected, or are likely to become affected, in any particular given case Causes Injury, inflammation of the periosteum or of the bone – sometimes following infection, possibly a vitamin D deficiency Signs In the early stages nothing more than a R fleeting lameness is seen Eventually the horse will go lame all day if it is worked, or becomes too lame to take out of the stable After a time one or other of the joints becomes enlarged, and the cause of the lameness becomes obvious It is only in the case of high ring-bones (around the pastern joint) that the exostosis can be felt; when the lower (coffin) joint is affected there is at first no outward visible or palpable sign; but after a time the hoof alters in shape, becomes distinctly bulged or ‘buttressed’ at the coronet This latter effect is due to the fact that in low ring-bone the extensor or pyramidal process of the coffin-bone is usually involved, and the deposit of bone upon it pushes the coronet, and the wall which grows from it, in an outward direction (‘pyramidal disease’) At times the alteration in the outline of the hoof is not by any means regular; it may be bulged at any point from one heel to the other, denoting a deposit of bone wherever there is a bulge In ‘true ring-bone’ the joint that is affected almost always ends by becoming stiff (ankylosed), owing to fusion between its complementary bones and obliteration of the joint having occurred In this state the horse may become fairly sound, because the pain occasioned by movement at the joint has disappeared, but the gait will always be stiff Treatment Prolonged rest in a loose-box or, preferably, at grass is indicated More harm than good results when blistering is carried out Corticosteroids may be used Ring Vaccination A disease-control process by which susceptible animals in a prescribed area surrounding an outbreak are vaccinated It is used, for example, in the control of foot-and-mouth disease where there is no slaughter and eradication policy Vaccination is begun at the perimeter of the areas, progressing inwards towards the centre For success, diagnosis, typing of virus and the vaccination itself must all be speedy Ringer’s Solution Ringer’s solution consists of sodium chloride, grams; calcium chloride, 0.25 g; potassium chloride, 0.42 g per litre ‘Ringwomb’ This is the colloquial name for a condition which sometimes complicates lambing, and is due to failure of the cervix to dilate Usually, the os uteri will admit or fingers, which can feel what seems like a firm ring The shepherd may recognise the condition on seeing a small portion of fetal membrane protruding from the vulva The ewe remains in good health (but does not lamb) until death and decomposition of the fetus occur Manual dilation of the cervix is practised by some veterinary surgeons Should this prove impossible, Caesarean operation is the only alternative (See UTERUS and PARTURITION.) Ringworm A contagious skin disease caused by the growth of certain fungi, which live either upon the surface of the skin or in the hairs of the areas affected Ringworm may affect any of the domesticated animals, but it is probably commonest in young store cattle when they are enclosed in buildings during winter, and in pet cats and kittens Dogs and horses are also frequently affected, but the disease is not often seen in the sheep and pig in the UK Ringworm and favus in the domesticated animals are caused by parasitic fungi which belong to the family Gymnoascidae Lesions generally Ringworm appears in the form of patches of dry, raised, crusty skin, from the surface of which the hairs have fallen and upon the surface of which there are scales or scabs The patches are often more or less circular, but in bad cases large irregular areas may be produced, which result from the coalescence of adjacent areas Favus is a type of ringworm Ringworm 607 A bare scaly patch on a kitten’s toe due to ringworm Ringworm in which the lesions have cup-shaped depressions which bear some similarity to a honeycomb, from which they get their name (favus, honeycomb) Favus affects the dog and cat, the mouse and rat, rabbits sometimes, and fowls occasionally Horses Ringworm may be due to parasites belonging to the genera Trichophyton or Microsporum In cases due to the former, the first affected areas are usually confined to the head, neck, withers, and sometimes to the root of the tail The hair becomes matted in patches about the size of a large coin, and in the centre of each patch appears a bare area from which the hair has fallen off; this gradually extends until the whole area is denuded The skin becomes raised and scurfy, and greyish-white crusts are formed; at times there may be grey or yellow scales adherent to begin with, but becoming detached later There is usually little or no itchiness, except when due to T mentagrophytes When the horse is affected with ringworm due to Microsporum parasites, practically any part of the body may be attacked Cattle Ringworm is nearly always due to T verrucosum infection It is very common among young animals in autumn, winter, and early spring, especially if they are kept indoors The head and neck are most often affected, especially the eyelids, lips, ears, and above the jaws, but it may occur anywhere on the body The lesion begins as a raised ring-like patch on which the hairs stand erect In a day or so the hairs fall off, and the surface of the skin becomes covered with masses of scales heaped up into a greyish-white or greyish-yellow crust The areas are usually very numerous and often The roughened appearance of an infected claw Microsporum canis Bodin was responsible become confluent, so that large areas become bare of hair and present roughened, crusty, hard, dry surfaces with a tendency towards pronounced wrinkling of the skin around and between them Where calves are extensively affected with ringworm there is always a good deal of loss of condition and itchiness Sheep When they are affected the fleece becomes matted, and falls out in circular patches over the shoulders, neck, and chest T verrucosum is one cause Control is by isolating affected animals and disinfecting troughs, etc Dogs Ringworm may be caused by one of genera: Trichophyton, Microsporum, Oidmella, or Oospora, the last-named causing favus The lesions produced by the first three of these are very similar in all respects to those seen in horses and cattle In favus caused by Oospora canina the lesion appears as a raised circular patch upon whose surface there is a pale yellow R 608 Ringworm crust with little depressions (honeycomb) scattered through it The skin in such cases is often very much thickened Hedgehogs Caused by T erinacei, this infection may cause lesions on the face of dogs where the skin has been damaged by the hedgehog’s spines Cats Ringworm is of kinds: due to Trichophyton, Microsporum and Achorion, the latter producing favus When due to the first two of these, the symptoms and lesions are similar to those seen in other animals (See ONYCHOMYCOSIS.) Cats become infected from mice with mouse favus (A quickeanum or A arlongi), although it may also be due to A schoenleinii – the favus of man The lesions are chiefly confined to the fore-paws and the head and the neck, though they may spread to other parts of the body Itchiness is usually absent The areas affected vary in size from that of a pin’s head up to a 5p piece or so, and are not always regular in outline The skin is thickened and the edges are raised When newly formed, the covering crust is yellow and soft to the touch, but when old it is grey and powdery The characteristic cupshaped depressions are seen in most cases, but when affecting the claws they may be absent Ringworm due to M canis Bodin is of publichealth importance It is often overlooked by owners, but children are readily affected Cats, especially Persians and other longhairs, may be ‘carriers’ of ringworm fungus In a survey involving 200 selected cats seen at a veterinary clinic, none of them showed any sign of ringworm Fur samples taken with a brush showed that 39 per cent of the 200 were carrying spores of ringworm fungi (In 72 samples the spores were those of M canis.) A survey in England of fur samples taken at cat shows revealed that, overall, 35 per cent of longhairs were carrying M canis spores Decontamination of households is important for human health after ringworm has been diagnosed Hypochlorite, benzalkonium chloride, and glutaraldehyde-based compounds are recommended Favus in the fowl, due to T gallinae, affects the comb, wattles, and other parts of the fowl’s head If the condition spreads down to feathered parts, the feathers become dry, brittle, and break off at the surface of the skin, leaving large bare areas There is always a most disagreeable odour from fowl favus Treatment Oral administration of griseofulvin is by far the simplest method Cattle and R Ringworm in the cat: whitish, scaly lesion can be seen to the right of the ear, above the white fur Rodent Ulcer horses can be given a supplemented feed This makes possible group treatment, and avoids handling of infected animals – thus reducing the risk of infection being transferred to man However, it is inadvisable not to use griseofulvin in pregnant animals In a cat which could not tolerate griseofulvin, a thiabendazole (see ANTHELMINTICS) dip was successfully used Natamycin and enilconazone which are used as a wash or spray can be applied to infected cattle and horses with a knapsack sprayer Ketaconazole, applied as a shampoo, may be used to treat dogs Otherwise, treatment consists, in the first place, of removing the hair from around the lesions, collecting it and burning it There are many suitable dressings to choose from: e.g gentian violet solution; undecylenate ointment; and copper naphthenate lotion, which has given rapid and good results in the treatment of ringworm in cattle A vaccine for use in cattle is available Dressing should be carried out twice a week for a fortnight for cattle and horses, and by then most of the fungus will be killed The cases should not be considered cured until there is a level crop of new hair over each of the areas For the smaller animals it is better to use the dressing once every 2nd day In all instances it is very important to remember that ringworm spreads from the centre outwards, and edges and margins of the areas should be especially well dressed Vaccination of calves against T verrucosum involves intramuscular doses, 10 to 14 days apart In Russia the vaccination of racehorses, and other horses taking part in competitive events, is compulsory Public health Ringworm is readily transmissible to human beings, so precautions such as hand-washing and disinfection after contact with known infected animals should not be neglected Dettol is useful for these purposes Diagnosis Microscopic examination or culture methods (See also WOOD’S LAMP.) 609 Roaming Roaming is a behavioural habit in certain male dogs and cats If the animal does not respond to training from an animal behaviourist, it may be castrated – although there is no guaranteee that this will stop the habit ‘Roaring’ in Horses An abnormal sound made when the horse breathes in; the usual cause has for long been regarded as vibration of the slackened vocal folds on one or both sides of the larynx, due to paralysis of the muscles which move the arytenoid cartilages outwards (For treatment and further details, see LARYNX, DISEASES OF – Laryngeal paralysis.) Rock Salt (see SALT – Salt licks) Rocky Mountain Fever Also called Rocky Mountain spotted fever, this is a disease of man caused by Rickettsia rickettsii Wild animals provide a reservoir of infection Rocky Mountain fever affects human beings usually between March and July The onset of fever is sudden, and in to days a rash appears over the whole body, including the palms of the hands The rash changes to a sort of mottling – petechiae, scattered over the skin, which gives the condition its name of ‘spotted fever’ The infection is transmitted by ticks, especially Dermacentor andersoni, the Rocky Mountain wood tick Dogs The infection causes fever, abdominal pain, depression, loss of appetite, nystagmus, with sometimes conjunctivitis and petechial haemorrhages in the mouth Oedema of a limb(s) is common, and the scrotum and prepuce may be similarly affected Over 30 cases are confirmed serologically each year, with many more being diagnosed, in Long Island, New York Diagnosis is most reliably confirmed by the immunofluorescent test Treatment is by antibiotics, e.g tetracycline (see RIBONUCLEIC ACID) Precautions There is a risk to veterinarians taking a blood sample or carrying out a post-mortem examination, as the rickettsia is present in the blood during the acute phase Road Accidents Rodent Ulcer Dogs and cats struck by cars may suffer chest injuries in addition to limb injuries (See FRACTURES; ACCIDENTS; DIAPHRAGMATOCELE; HYDROTHORAX; PNEUMOTHORAX.) In human medicine this term is reserved for carcinoma of the skin, but is sometimes misapplied by animal-owners to EOSINOPHILIC GRANULOMA or LICK GRANULOMA RNA R 610 Rodents Rodents Rostral Rats and mice are important from a veterinary point of view on account of the diseases which they may transmit to domestic animals For examples, see AUJESZKY’S DISEASE; SALMONELLOSIS; LEPTOSPIROSIS; RINGWORM; FOOT-ANDMOUTH DISEASE In countries where the disease is present, rodents may transmit RABIES Towards the nose or front end of the body Zoonoses Members of the family Muridae (Old World rats and mice) can infect man with plague, tularaemia, listeriosis, pseudotuberculosis, erysipelas, leptospirosis, brucellosis, melioidosis, murine typhus, Q fever, scrub typhus and other rickettsioses, histoplasmosis, lymphocytic choriomeningitis, Lassa fever, rabies and other viral infections, Asian schistosomiasis, Chagas disease, rat-bite fever, and HANTAvirus Rostral teeth are the incisors and canines Rotavirus So-called because of its resemblance to a wheel Responsible for causing diarrhoea in the young of many species – children, foals, calves and piglets It has been shown that, in piglets, only the pig and calf rotaviruses cause diarrhoea, although the human and foal rotaviruses can replicate in the pig Research at the Moredun Institute led to a method of diagnosis based on the direct detection of the viral nucleic acid, which comprises 11 molecules of double-stranded DNA This method is ‘rapid and as sensitive as ELISA’ Rodenticides In the UK brodifacoum was cleared by MAFF (for indoor use only) in 1984; and difenacoum had also been scrutinised under the Pesticides Safety Precautions Scheme (No incidents linking barn owl deaths with these two rodenticides had been reported in the UK.) A calciferol preparation, Rodin C (Rentokil) – claimed to be effective against warfarin-resistant rats – had earlier received MAFF approval (See also WARFARIN.) ALPHACHLORALOSE is used for the same purpose A rodenticide containing vitamin D1 caused the death of dogs A vaccine Rotavec K99 (Schering-Plough) Signs Weakness, anorexia, vomiting and passing Rothera’s Test blood Accidental poisoning of domestic animals from above, R has occurredbannedsome of the e.g REDand also from others in the UK, SQUILL; THALLIUM; ANTU; THIOUREA; PHOSPHORUS; FLUOROACETATE; barium salts; zinc phosphide; STRYCHNINE Romagnola An Italian breed of cattle, white in colour, and reared for beef Romagnolas have been imported into the UK Rompun Proprietary name for XYLAZINE Rose Bengal Plate Test A simple and quick screening test used in the diagnosis of brucellosis in cattle Sera giving positive results may then be tested by means of the Serum Agglutination Test and Complement Fixation Test was introduced in 1986, following research at Moredun, to protect calves against rotavirus (and also K99 E coli) The vaccine is used to immunise cows in late pregnancy, producing enhanced antibody levels in the colostrum; this is given to calves at the rate of 2.5 to 3.5 litres daily for the first weeks of life Rotenone The insecticidal principle of derris root Rotenone is highly poisonous to fish and is used deliberately for removing coarse fish from enclosed waters before establishing trout fisheries A test for ketones in milk or urine; a modified version requires the following reagent: ammonium sulphate, 100 g; anhydrous sodium carbonate, 50 g; sodium nitroprusside, g If the bottom half-inch of a test-tube is filled with this powder, and a little of the fluid to be tested runs down the side of the tube, a red colour will develop after or minutes if ketones are present, as with acetonaemia Roughage By this is meant food of a bulky and fibrous nature, such as hay and straw These have a low water-content, and are in a sense the opposite of succulents, e.g kale, silage (See also DIET AND DIETETICS – Fibre.) Rottweiler A large powerful breed developed as a guard dog in Germany The breed is prone to deafness and retinal dysplasia; hip dysplasia may also be a problem Roundworms (Nematoda) 611 The rotavirus (By courtesy of the AFRC.) Rough Collie A rough-coated medium-sized dog with an elongated face and nose, orginally developed as a sheep-dog The breed is prone to cleft palate, corneal dystrophy, deafness, epilepsy and umbilical hernia Central progressive retinal atrophy is a dominant trait; collie-eye anomaly is a recessive trait Patent ductus arteriosus may be inherited, as may neutropenia Rouleaux Rouleaux is the term applied to the columns into which red blood cells collect as seen under the microscope The appearance somewhat resembles a pile of stacked coins Round Heart Disease In chickens, this occurs only on some types of deep litter The cause is not known, but litter from affected houses can transmit the disease to healthy chickens Sudden death occurs; on post-mortem examination, the heart is firm, bright pink in colour, barrel shaped and with a dimple at the apex Replacement of the litter stops mortality In turkeys, the disease is more common in the small white strains It causes sudden death in birds in apparently good condition There appears to be a genetic factor Roundhouse A type of circular farrowing pen devised in New Zealand It consists of a circle of hardboard, about 2.4 m (8 feet) in diameter and 1.2 m (4 feet) high, bolted to a light iron framework and fitted with an internal creep rail A smaller circle, about m (3 feet) in diameter, made partly of hardboard and partly of tubular rails, is fitted eccentrically within the larger one, and the whole is fastened with bolts to the concrete floor of the piggery The smaller circle, which is warmed by an infra-red lamp, acts as a creep for the piglets, while the sow is kept in the space between the circles Because of the shape of this space, the sow invariably lies in the same position, with her udder towards the piglet’s creep This gives the piglets the maximum degree of safety Roundworms (Nematoda) Most nematodes lay eggs, but some produce living larvae The life-history may be direct or indirect, i.e an intermediate host may be necessary Nematodes can be the cause of anaemia, wasting, gastroenteritis, bronchitis and pneumonia, aneurism, convulsions and blockage of the intestine Some are of public health importance (See TRICHINOSIS; TOXOCARA.) Horses Stomach Two species of Habronema (H muscae and H microstoma), and Drascheia megastoma, inhabit the stomach of Equidae in various parts of the world R 612 Roundworms (Nematoda) The New Zealand pen: a drawing showing the position which the sow voluntarily assumes, and, below, a plan for the pen’s construction (See entry for Roundhouse.) R The worm larvae are passed in the horse’s faeces; swallowed by maggots, and continue through the pupal and adult stages of the stablefly or house-fly; finally the larvae become located in the fly’s proboscis When the fly settles near a horse’s mouth, the larvae enter it, and reach the stomach However, if the horse has a wound, some of the larvae will be attracted to that, and give rise to the cutaneous or orbital form of habronemiasis, ‘summer sores’ or ‘bursati’ Habronemiasis is common in the tropics and subtropics, but has also been seen in the UK Hard nodules or granulomas may form on the skin or at the inner canthus of the eye D megastoma forms nodules, in which it lives, in the stomach Habronema worms may penetrate the gastric mucosa and become embedded causing gastritis, thirst, colic and pica Trichostrongylus axei, seldom more than mm long, also causes gastritis This worm also inhabits the duodenum Small intestine Parascaris equorum is the common large roundworm of the horse The female may be up to 50 cm long Pica, colic and unthriftiness may result from heavy infections, which may also lead to partial blockage of the intestine The larvae, which migrate to the lungs after hatching in the stomach, are capable of causing a catarrhal bronchitis or broncho-pneumonia; and possibly some damage to the liver also, during their migration through that organ Strongyloides westeri is another worm found in the duodenum, and a cause of diarrhoea in foals This and other worms of this genus may also cause broncho-pneumonia Caecum and colon Strongylus Three species are important Strongylus (head) (Left to right) S edentatus, S vulgaris, S equinus Roundworms (Nematoda) S (Delafontia) vulgaris is a cause of verminous arteritis, or thrombosis, affecting the cranial mesenteric artery (See EQUINE VERMINOUS ARTERITIS.) S (Alfortia) edentatus produces nodules in the peritoneum If very numerous, the larvae may cause peritonitis, bleeding, and anaemia After or months they return to the large intestine and become adult worms S equinus The larvae of this large worm also produce nodules in the caecum and colon, and later migrate to the liver and pancreas Oxyuris equi The female worm comes to the end of the rectum to deposit its eggs, which are ejected as a yellowish or greenish mass surrounding the anus Resulting pruritus can lead to emaciation in severe cases, and more usually to unsightly bare patches on the tail and hindquarters Lungs Dictyocaulus arnfieldi is the cause of a verminous bronchitis which may be recognised by a cough and, if the worms are numerous, by loss of appetite and emaciation ‘Demonstration of the presence of larvae in the faeces is sufficient to confirm the presence of infection in donkeys, but even if respiratory symptoms are present, this finding should not be allowed to obscure the more likely possibility that other causal agents are involved Diagnosis of infection in horses may be very difficult Recovery of larvae from faeces will identify the “silent carriers” but most horses have very low larval output and several examinations may be necessary Most cases of clinical disease, in horses, are seen during the prepatent phase and larvae will not therefore be present in the faeces Most infected horses, although showing respiratory signs, not develop patent infections It is therefore important not to exclude lungworm as a possibility just because it is not possible to recover larvae from the faeces Naturally acquired infections are known in which larvae were not recovered from horses with clinical respiratory signs extending for more than a year Complete recovery followed specific lungworm therapy While an association with donkeys is added circumstantial evidence on which diagnosis can be based, infection may be transmitted from horse to horse in the absence of a donkey contact This frequently occurs on thoroughbred studs.’ The efficacy of orally administered ivermectin against induced D arnfieldi infection was evaluated in a controlled study comprising 12 yearling ponies Treatment with ivermectin paste, orally once, was 100 per cent effective against both adult and immature or inhibited stages of the horse lungworm 613 Connective tissue Onchocerca O reticulata is found in the horse, especially in tendons It is common near the suspensory ligament, but is also reported in the withers They may cause no symptoms, or may induce hypertrophy of the tendon or may cause fistulous withers O cervicalis occurs in the ligamentum nuchae of equines, and is often associated with poll-evil Skin Parafilaria multi-papillosa (Filaria haemor-rhagica) is found in intermuscular tissue or under the skin The female worms penetrate the latter to lay their eggs on the surface, where hard nodules subsequently develop, and these open and bleed Haematobia flies in Russia, and Drosophila in tropical regions, transmit the worm larvae Nervous system The larvae of Setaria equina invade the central nervous system of horses in Asia, causing epizootic cerebrospinal nematodiasis This is characterised by paralysis, and the disease may prove fatal The adult worm, milky-white, lives in the peritoneal cavity Transmission is by mosquitoes Eyes Thelazia lachrymalis causes conjunctivis (and sometimes keratitis too) (See EYEWORMS.) Cattle, sheep and goats Oesophagus and stomach Gongylonema Two species occur in ruminants and in pigs They are found just below the epithelium in the thoracic third of the oesophagus The intermediate hosts are various species of dung-beetles Haemonchus contortus This is the large stomach worm or ‘barber’s pole’ worm of ruminants, so-called because of the female’s spiral red and white stripes The male is red It is a trichostrongyle, with a length of about 30 mm and the thickness of a pin It is a voracious blood-sucker, and inhabits the abomasum It can cause serious anaemia and unthriftiness, especially in lambs H placei is another of several species Ostertagia worms, which are of considerable economic importance, are peculiar in that while most infective larvae living in the abomasum moult twice to become adults, some – especially perhaps those ingested by the calf during late summer and autumn – moult only once and remain as 4th-stage larvae in a dormant state These dormant larvae are unaffected by many anthelmintics but are usually, though not always, susceptible to ivermectin, fenbendazole and albendazole Later they develop into adults R 614 Roundworms (Nematoda) causing a winter outbreak of gastroenteritis Calves should therefore be dosed in September and moved to ‘clean’ pasture Also known as the small brown stomach worm, Ostertagia cause severe irritation of the mucous membrane by the formation of nodules Infested animals may lose weight, scour, and become anaemic Small intestine Ascaris vitulorum This large round worm of cattle is generally of little importance, but it may be a frequent and fatal parasite of calves in certain localities Nematodirus This is a common trichostrongyle genus found in large numbers in the small intestine of sheep It is a very slender form under 2.5 cm long In recent years nematodirus infestation has caused severe losses The infestation is a ‘lamb-to-lamb’ one, and can be avoided – where practicable – by confining lambs to pasture which carried no lambs in the previous seasons Nematodirus species found in Britain are N filicollis, N helvetianus, N spathiges, and N battus N helvetianus and N battus are parasites of calves (See PASTURE, CONTAMINATION OF.) Cooperia species are important They are usually present in association with other species of worms, e.g Ostertagia, Trichostrongylus They seldom cause anaemia, but are responsible for weight loss and scouring Trichostrongylus worms are very small (only to mm long) and inhabit the abomasum and duodenum Bunestomum (hookworms) live in the small intestine The larvae may either enter their host via the mouth or penetrate the skin They suck blood and accordingly cause anaemia and sometimes oedema under the throat (See HOOKWORMS.) Oesophagostomum This is a genus of strongyle worms related to the horse forms, and found in ruminants and pigs They are about 2.5 cm long They are the cause of nodular disease of the intestine (‘pimply gut’) If present in small numbers, the only result is to render the intestine unfit for sausage skins If in large numbers, the symptoms are anaemia, emaciation, diarrhoea, and oedema The disease in this case often has a fatal termination Trichuris This genus of whip-worm occurs in the caecum of various animals, but is usually of little importance The worms have very slender R Life-cycle of the large roundworm of the horse, Parascaris equorum (Reproduced with permission from H T B Hall, Diseases and Parasites of Livestock in the Tropics, Longman.) Roundworms (Nematoda) 615 is less prominent than in the above form, but breathing is difficult Oesophagostomum (head-end) necks with stoutish bodies The necks are threaded through the mucous membrane of their host They may cause inflammation at the point of insertion of the head and may admit bacteria Strongyloides worms are found in the small intestine, often deep in the mucosa Scouring is caused in heavy infestations The worm larvae can enter the body via the skin Lungs Dictyocaulus Three species are known in cattle, but only is important – D viviparus, which causes a form of bronchitis The male is about cm long and the female about cm Eggs hatch in the lung, and the larvae climbing up the trachea are swallowed, passing to the exterior with the faeces After moulting twice, they reach the resistant infective stage, and can live thus on pasture through the winter When swallowed, they continue their development The signs and treatment are described under PARASITIC BRONCHITIS Parasitic bronchitis (‘husk’) Several species of roundworm occur in sheep and goats Dictyocaulus filaria is the largest and most common species The male is about cm long and the female cm The infective stage is reached in about 10 days Apparently lambs can be infected prenatally This worm is cosmopolitan in its distribution Its life-history is direct The symptoms are those of a verminous bronchitis, sometimes complicated by bacterial infection, but otherwise similar to those in cattle Protostrongylus (Synthetocaulus) rufescens is a red and much smaller form The male is about cm and the female cm long It is found mainly in Europe These worms live in the bronchioles and in the pulmonary parenchyma, and cause a verminous lobular pneumonia The eggs cause a diffuse nodular pneumonia Cough Connective tissues Onchocerca Several species occur in cattle in various parts of the world They are the cause of ‘worm nodules’ The nodules are found mainly in the brisket, but also occur in the flank and forequarters They appear to cause little harm to their host, but as the capsule is a product of inflammation, beef containing worm nodules is condemned, and in Australia they have caused considerable loss in the export trade Dracunculus Only species of this worm is found in the domestic animals, D medinensis, the ‘guinea worm’ It is found in India, Africa, and South America The female is of considerable length, but is generally recovered from the host in small pieces It is milky white in colour, smooth and without markings Nearly the whole of the worm is occupied by the uterus, packed with coiled-up embryos The worm occupies a subcuticular site, as a rule in the extremities, with the head-end projecting to the exterior The larvae are released by a prolapse of the uterus through the cuticle of the worm They escape into the water, and are swallowed by a cyclops in which they develop The cyclops is in due course swallowed in the drinking water by a suitable host – practically any of the domestic animals will – and larvae are released by the digestive juices and proceed to their adult habitats The worm may give rise to local abscesses, and sometimes affects the feet of dogs Eye Thelazia (See EYEWORMS.) Pigs Stomach The most important worm here is Hyostrongylus rubidus Its life-cycle is direct (See also THIN SOW SYNDROME.) The latter may sometimes be due to various species of Oesophagostomum worms (See OESOPHAGOSTOMIASIS.) Small intestine Ascaris suum This worm is a very common parasite of pigs in all countries The eggs have a remarkable vitality, and have been kept alive for as long as years The egg, in a few weeks after passing to the ground, develops an embryo, but this does not hatch until the egg is swallowed When this happens, the larva, which is about 0.25 mm long, bores through the intestine, reaches the bloodstream, and is carried through the liver and heart to the lungs Here it remains for some days, but it finally climbs up the R 616 Roundworms (Nematoda) trachea and is swallowed The larva which leaves the lung has grown to about 2.5 mm in length In the intestine it continues its development, taking about 21⁄2 months to so In passing through the lungs a certain amount of bleeding is caused, and if the larvae are numerous, pneumonia results During this period the animal shows the symptoms known as ‘thumps’ If it survives the lung symptoms, it often fails to grow properly and remains small and stunted Macrocantorhynchus hirudinaceus is found in the small intestine of pigs It is a whitish worm, the male being to 10 cm long, while the female is 20 to 35 cm long The neck is thin and the posterior region stout The intermediate stages are found in beetles The parasite may cause a catarrhal enteritis or even actual perforation with peritonitis Trichuris suis, the pig whip-worm, causes mainly subclinical disease in temperate climates, but in the tropics it may cause dysentery, anaemia, and even death In the Americas up to 85 per cent of pigs may be infested; in some areas of the UK, from 75 per cent Trichuris occurs in the caecum Treatment in the pig includes oxibendazole, fenbendzole and thiophanate Lungs In pigs species are common, both belonging to the genus Metastrongylus The male is about cm and the female about cm long Both species are common in Europe and America, and may occur in the same pig They cause a verminous bronchitis and sometimes pneumonia Young animals are more susceptible and may die from it Both species are carried by earthworms R Muscles Trichinella spiralis This is a small worm found in the intestine The female produces living larvae (0.1 to 0.16 mm long) which migrate through the mucosa, reach the bloodstream, and are carried to various muscles Here they pass into a cystic stage (the cyst being formed by the host), in which they remain until they are swallowed by some flesh-eating host or until they calcify and degenerate In the intestine of the new host they reach sexual maturity and produce a new lot of larvae, which in turn migrate to the muscles The normal hosts are carnivores (dogs and cats) Rodents may be infected, and rats can be a source of infection to pigs Man may be infected from the pig (See under TRICHINOSIS.) Kidney Stephanurus dentatus is a thickish worm of fair size, the male being nearly cm long and the female a little larger It is found as a rule in the kidney fat of pigs, but also occurs in the liver and other locations in these animals and in ruminants It is found in America and Australia, and is responsible for considerable damage Its life-cycle is similar to that of the hookworms Thiabendazole, fenbendazole and ivermerctin have proved effective in controlling this parasite Dogs and cats Oesophagus Spirocerca lupi is found in nodules in the oesophagus and, less frequently, the stomach of the dog, in all hot countries and in Europe It is a reddish worm The male is to cm long The intermediate hosts are various beetles and cockroaches The disease is often undiagnosed during life, but in countries where it is common the presence of the worm may be suspected from a frequent cough followed by repeated vomiting Death from exhaustion may result Damage to the carotid artery by S lupi worms (3 in each of nodules attached to the oesophagus) led to the death in the UK of an Alsatian from internal haemorrhage This parasite appears also to be closely associated with sarcoma of the oseophagus Stomach A microscopic gastric nematode of cats, Ollulanus tricuspis, has been found in the Americas, Australasia, and Europe The worm causes unthriftiness and vomiting in kittens Small intestine Ascarids include several species that occur in dogs and cats In cats the species seem to be Ascaris tubaeforme and A braziliense Hookworms in dogs Two species of hookworm are found in dogs: Ancylostoma caninum and Uncinaria stenocephala The latter is found in Britain These are smallish worms, about 2.5 cm long, found in the small intestine Eggs are passed to the exterior in the faeces and hatch in the soil or water After several moults, the resulting larva becomes infective, and is able to gain access to the host either in the food or by penetrating the unbroken skin It enters the bloodstream and is carried to the lungs It then passes up the trachea and is swallowed It completes its development in the small intestine, where it becomes mature Royal College of Veterinary Surgeons (RCVS) Caecum The whip-worm Trichuris vulpis occurs in the UK, and gives rise to diarrhoea/dysentery, loss of condition and a harsh, staring coat Heart Dirofilaria There are species occurring in dogs and cats D immitis occurs in the heart of the dog and occasionally the cat The female may reach a length of 30 cm, but the male is little more than half this size It is found in Asia and, of recent years, in Britain The embryos are hatched in the body of the female, and the young larvae, passed into the bloodstream, are sucked up by a mosquito in which they develop After a certain period they escape from the fly, when it attacks another dog, and entering the blood are carried to the heart, where they complete their development The worms interfere to a greater or lesser extent with the circulation No symptoms may be shown; or the dog may suddenly die Other symptoms include anaemia, respiratory troubles, ascites, etc Various complications may be due to emboli, such as cough, dyspnoea, etc Diagnosis is by demonstration of the microfilaria in the blood Another heartworm of the dog is Angiostrongylus vasorum, which has, as intermediate hosts, slugs and snails This worm, which has caused an outbreak of infestation in kennels in Ireland, lives in the pulmonary artery and the right ventricle of the heart Symptoms include malaise, stiffness on running, and subcutaneous swellings (due to suppression of normal blood clotting by the parasites) Some lung damage may be caused; likewise anaemia (See also under HEARTWORMS.) Kidney Dioctophyme renale The kidney worm of dogs and wild carnivores is very large, reaching m in length, and is a blood-red colour It is found in Europe and the USA It occurs in the pelvis of the kidney, and occasionally destroys the kidney tissue, to leave only the wall as a cyst filled with a purulent fluid The other kidney usually shows a compensatory hypertrophy It is occasionally found in the bladder Infestation follows the eating of raw fish The worm’s eggs are barrel-shaped and may be seen in the urine, under the microscope Bladder In the UK the bladder-worm Capillaria plica is rare, and seldom gives rise to obvious symptoms A severe infestation can lead to inflammation of the bladder and a mucoid discharge from vagina or prepuce In cats cystitis may, rarely, be caused by C feliscati 617 Trachea Oslerus (Filaroides) osleri occurs in the UK and gives rise to a sporadic but persistent cough, especially on exercise or if the dog is excited Retching may be caused Severe infestation can give rise to emaciation despite a fair appetite, laboured breathing, sleeping standing, and death in young dogs For control, thiabendazole has given promising results Another tracheal worm, Capillaria aerophilia, seldom gives rise to obvious symptoms Lungs A minute worm lives in the lungs of cats in Britain and elsewhere in Europe and America It may cause a fatal form of parasitic pneumonia The parasite (Aelurostrongylus abstrusus) is transmitted to cats by mice In Africa, Bronchostrongylus subcrenatus is found Lung lesions found at the autopsy of out of a batch of 20 beagles were due to Filaroides species, ‘probably F milksi rather than F hirthi’ The lungs had the appearance of being peppered with black spots Signs of larval migration were seen microscopically in the liver, mesenteric lymph nodes, and gastrointestinal tract Poultry Roundworms more commonly occur in free-range systems where it is also difficult to ensure that all birds can be treated There may be no obvious clinical signs but breeding flocks (chickens and turkeys) often show reduced hatchability Public health aspects (see under TOXOCARA) Rous Sarcoma of Chickens This is produced by a virus (See under CANCER.) Royal Army Veterinary Corps (RAVC) It has a long and honourable history An Army Veterinary Service was established in 1796; this became the Army Veterinary Corps in 1906, the title of ‘Royal’ being bestowed in 1918 A History of the RAVC 1796–1919 was compiled by Major-General Sir Frederick Smith KCMG, CB, a former Director-General, Army Veterinary Services, and published by Baillière, Tindall & Cox A 2nd volume, by Brigadier J Clabby, was published in 1963 by J A Allen & Co Royal College of Veterinary Surgeons (RCVS) Belgravia House, 62–64 Horseferry Road, London SW1P AF The governing body of the veterinary profession in the UK (See also REGISTER.) R 618 -Rrhaphy -Rrhaphy -Rrhaphy is a suffix meaning an operation in which some opening or tear is closed by stitches Rubarth’s Disease (Hepatitis Contagiosa Canis) This is named after the Swedish scientist Rubarth who, in 1947, described for the first time a disease in dogs which he called, on account of its contagious nature and the damage caused to the liver, Hepatitis contagiosa canis This is now commonly known as CANINE VIRAL HEPATITIS He regarded this disease, on the basis of the microscopical findings, as identical with fox encephalitis, which had been known in America for some 17 years previously Rubber Bands These sometimes get, or are put, on to the legs of cats (and possibly dogs), where they may remain unnoticed until the continual pressure has destroyed the skin beneath the band and caused damage to the underlying structures Gangrene or loss of use of the limb results A successful prosecution has followed the application of rubber bands to cows’ teats in the UK Rubber rings have been used for castration of lambs and calves, and for the docking of lambs (See ELASTRATOR, etc.) ‘Rubber Jaw’ R A condition seen in the dog in some cases of chronic nephritis It may be associated with enlargement of the parathyroid glands Softening of the bones of the skull, particularly the jaw, occurs, and in a severely affected part the bone can be cut with a scalpel There is resorption of bone and its replacement by vascular fibrous tissue ‘Rubber jaw’ is not, of course, seen in all cases of chronic nephritis, though some changes may be detected microscopically Rumen The 1st stomach of ruminants It lies on the left side of the body, occupying the whole of the left side of the abdomen and even stretching across the median plane of the body to the right side It is a capacious sac which is subdivided into an upper or dorsal sac and a lower or ventral sac, each of which has a blind sac, at its posterior extremity These divisions are defined by the presence of grooves on the outside of the organ and by pillars or ridges internally The whole organ is lined by mucous membrane which possesses a papillated, stratified, squamous epithelium containing no digestive glands, but mucus-secreting glands are present in large numbers Its entrance is through the oesophagus, and its exit is into the reticulum or 2nd stomach through the rumeno-reticular orifice Coarse, partially chewed food is stored and churned in the rumen until such time as the animal finds circumstances convenient for rumination When this occurs, little balls of food are regurgitated through the oesophagus into the mouth, and are subjected to a second, more thorough mastication Each bolus is chewed 30 to 60 times and mixed with copious amounts of saliva, to be swallowed and passed onwards into other parts of the compound stomach In rare instances, the rumen may be situated on the right-hand side Rumen Flukes Belonging to the genus Paramphistomum, these are found in both the tropics and North America Conical in shape, round in cross-section, they inhabit not only the rumen but also the reticulum, and – when immature – the duodenum They are also found occasionally in the bile ducts and urinary bladder Little damage is caused to the rumen, but in young animals a severe enteritis is the important aspect of the disease, resulting in diarrhoea, unthriftiness, anaemia, and sometimes death Paramphistomum flukes have a life-history similar to that of the common liver-fluke Fasciola hepatica; several species of snails being the intermediate hosts Rumen, Ulceration of In calves, ulcers in the rumen may be associated with lesions of the liver caused by Bacteroides (Fusiformis necrophorus), or with BVD infection (See also STOMACH, DISEASES OF.) Rumenotomy Opening the rumen via the left upper flank for the purpose of emptying the contents Ruminal Digestion In the rumen, bacteria break down the cellulose (which forms the structural materials of plants), and starch by means of enzymes, and convert them into fatty acids The bacteria fall a prey to the protozoa which, besides digesting starch, Runting and Stunting Syndrome thus perform the useful task of converting plant protein into animal protein This becomes available to the cow when the protozoa are, in their turn, destroyed further down the digestive tract and themselves digested A sample taken from the rumen, at the Hannah Research Institute, contained 100 million protozoa and million bacteria (giving some idea of the proportion of the two) Examples of protozoa included Entodiniomorph species, which feed on plant material, bacteria, and each other; and Holotrich species, which ferment soluble sugars from plants and feed on bacteria (See also under, DIET AND DIETETICS – Fibre; LACTIC ACID.) Ruminal Tympany (see BLOAT) Rumination (‘Cudding’) Rumination (‘cudding’) is the process whereby food taken into the stomachs of ruminants is returned to the mouth, subjected to a second, more thorough chewing, and is again swallowed The act occurs at intervals of from to hours, and occupies a longer or shorter time according to the nature of the food and the amount taken at the last meal It usually commences about half an hour after feeding ceases, and probably continues until all the coarser constituents have been re-chewed, or at least until the animal is disturbed This fact is of considerable importance practically; cattle and sheep should be allowed at least hours’ rest after feeding before they are subjected to any severe exertion Disregard of this is a fruitful contributory cause of stomach disorders in both cattle and sheep (See also under RUMEN.) The act of regurgitation appears to be in reality a complex one, but it may be briefly summarised as follows: (1) The tension of the oesophagus relaxes, partly by dilatation, and partly through an inspiratory movement of the diaphragm (the glottis being temporarily closed), which reduces pressure in the thorax (2) The rumen and the reticulum powerfully contract and squeeze upon their contents (3) The abdominal muscles contract and raise the intra-abdominal pressure The direct result is that ingested foodstuffs are forced from the area of high pressure (i.e the rumen and reticulum) through the open oesophagus into an area of lower pressure (i.e into the thoracic portion of the oesophagus) When a small quantity, sufficient to form a bolus or ‘cud’, has entered the oesophagus, the 619 lips of the oesophageal groove and the muscles in the vicinity close the terminal part of the oesophagus, and there commences an antiperistaltic movement which conveys the ‘cud’ upwards past the closed glottis, underneath the soft palate, and so into the mouth Excess fluid is immediately squeezed from the mass and swallowed, and chewing movements commence at once Each bolus is chewed 30 to 60 times according to its consistency, size, and to the nature of its constituents; coarse straw or hay fodder requiring the longest time The chewing occupies from 30 to 90 seconds, and then the bolus is rolled up by the dorsum of the tongue and again swallowed In from to seconds another bolus has reached the mouth, and so the process is continued ‘Run-back’ This must be avoided by means of back fences (See under STRIP GRAZING.) Runch (see CHARLOCK POISONING) ‘Runners’ This is an old, popular term for hounds unable to gallop properly ‘Runners’ are usually recognised as such when they return to hunt kennels at about months old after being walked; and they are then often culled from the pack Technically, the condition is known as osteochondrosis of the spine Symptoms include poor muscular development in the spinal region, poor bodily condition, an unnatural gait, and often inability to jump a fence successfully negotiated by the rest of the pack Some curvature and rigidity of the spine may also be observed It seems that this is, in part at least, an inherited defect of foxhounds The term is also applied to young budgerigars affected by French moult Runt Pigs Runt pigs can be reared in special nursing units designed for runts and excess piglets in a litter Runt pigs and underweight babies have similar biochemical and physiological abnormalities Runting and Stunting Syndrome A condition of economic importance in poultry production Clinical signs include pallor of the skin, decreased skeletal density, lameness, late development of plumage, distortion and bending of quills or primary feathers and orange-coloured mucus in the droppings, along with particles of undigested food The problem R 620 Rupture occurs sporadically and tends to last for abou a year on the farm before any improvement is seen Retroviruses, enteroviruses and other viral agents, as well as anaerobic bacteria, have all been suspected as the cause Disappearance of the syndrome over much of the USA coincided with the use of reovirus vaccines Rupture Rupture is a popular name for HERNIA The term is also applied to the tearing across of a muscle, tendon, ligament, artery, nerve, etc Rupture of the aorta is a cause of death in male turkeys at to 22 weeks old Russian Gad-Fly (Rhinoestrus purpureus.) This attacks horses in Europe and North Africa Russian Spring-Summer Virus Russian spring-summer virus causes an encephalitis of man and goat, caused by a virus R and transmitted by the tick Ixodes ricinus in Russia, Poland, the Czech Republic and Slovakia Rye-Grass Rye-grass poisoning has caused the death of cattle and horses restricted to grazing rye-grass pasture (Lolium perenne) In New Zealand and Australia, a fungus present on the rye-grass may cause facial eczema A staggering gait – and convulsions – may occur in cattle and sheep on rye-grass pasture giving rise to the colloquial name ‘rye-grass staggers’ In a UK outbreak in sheep, they had ‘a rocking-horse gait, and when chased fell down and trembled violently’ (Veterinary Investigation Service report.) Fungal toxins are the cause of ‘rye-grass staggers’ in both the UK and New Zealand The rye grass is infected with a seed-borne enfophytic fungus, Acremonium lolii, containing the alkaloid loitrem B (See also CEREBROCORTICAL NECROSIS.) ... developed for research purposes A radio transmitter, the size of an ordinary drug capsule, can give information concerning pressure, temperature or pH within an organ R 588 Radius Radius The inner of... sea marsh land in Lincolnshire that had previously been used for fattening imported Irish steers which were carriers of The Register of Veterinary Surgeons lists veterinary surgeons who can practise... public libraries or is obtainable from the Royal College of Veterinary Surgeons, Belgravia House, 62–64 Horseferry Road, London SW1P 2AF Reproduction 595 Rehydration Reproduction The restoration