Jaagsiekte A disease of adult sheep, first recognised in South Africa. ( See PULMONARY ADENOMATOSIS .) Jack A male donkey. Jack Beans Jack Beans may cause poisoning if fed raw. ( See LEGUME POISONING.) Jack Russell Terrier A small, lively dog, having a white coat with brown or black patches. Originally a cross- breed, it now breeds true. Prone to patellar luxation, it may inherit ataxia, lens luxation and Perthe’s disease. Jacobson’s Organ Also known as the vomeronasal organ, this is associated with the detection of flavours such as those of food, but is thought also to be able to detect pheromones. The organ has 2 small tubes which extend from the floor of the nasal cavity to the level of the 2nd/4th cheek tooth. It is active in most mammals, but even more highly developed in certain reptiles, especially snakes. Janet A female mule. Japanese B Encephalitis This disease is present in Nepal and other regions of Asia. Cause A flavivirus. The disease is transmitted by mosquitoes from avian species which act as reservoirs of infection but are themselves asymptomatic. Signs In horses, the sight is affected first. Later they become drowsy. Many die, and the recov- ery of others is seldom complete. Pigs are also susceptible; abortion and stillbirths result from infection. The disease is a zoonosis, and for its preven- tion in people a vaccine has been used. Japanese Bobtail A breed of cat of ‘foreign’ conformation with a rudimentary tail. The hind-legs are longer than the fore-legs but are kept angled so that the back is level. There are similarities with the Manx, but there does not appear to be the same frequency of defects as occurs in that breed. Japanese Tosa A breed of dog raised in Japan for fighting. Importation into the UK is banned under the Dangerous Dogs Act. Jaundice Jaundice is a yellowish discoloration of the visi- ble mucous membranes of the body (eye, nose, mouth, and genital organs). The discoloration is caused by bilirubin, an orange-yellow pig- ment produced following the breakdown of erythrocytes due to liver disease or obstruction of the bile flow from the liver and gall-bladder. The symptom of jaundice (icterus) may also follow the destruction of red blood cells by parasites, such as may occur in cases of biliary fever and surra in the horse; red-water in cattle; malignant jaundice (canine babesio- sis); it is seen also in leptospiral jaundice ( see LEPTOSPIROSIS ), and canine viral hepatitis. In cats, jaundice is seen in the dry form of feline infectious peritonitis, toxoplasmosis. Jaundice may indicate an incompatibility between the blood of sire and dam causing haemolytic jaundice of the newborn foal or piglet. When bile cannot enter into the small intes- tine by the bile-duct from the liver in the usual way, it becomes dammed back, is absorbed by the lymphatics and the blood vessels, carried into the general circulation, and some of its constituents are deposited in the tissues. ( See GALL-STONES , also under GALL-BLADDER ; CIR- RHOSIS; LIVER, DISEASES OF; EQUINE BILIARY FEVER .) It may be seen during poisoning with copper, mercury, phosphorus, chloroform, or lead, and after some snakebites. Aflatoxins may cause jaundice. ( See also LEPTOSPIROSIS; JAUNDICE; FOALS, DISEASES OF; and BILIARY FEVER.) Jaundice, Leptospiral ( see under LEPTOSPIROSIS for the appropriate animal) Java Bean Poisoning The Java beans, Phaseolus lunatus, were once imported in large amounts. The beans are of varying origin, and differ in colour, thus: Java beans are as a rule reddish-brown, but they may be almost black; Rangoon or Burmah beans are J smaller, plumper, and lighter in colour (so- called ‘red-Rangoons’ are pinkish with small purple splashes). The active poisonous agent in the beans is a substance called phaseolunatin, which is a member of a group of cyanogenetic glucosides. Signs These are exactly the same as those given under HYDROCYANIC ACID . Jaw The upper jawbones are 2 in number and are firmly united to the other bones of the face. The lower jaw – mandible or coronoid process – is composed of a single bone in horse, pig, dog, and cat, but in the ruminants the fusion between right and left sides does not occur until old age. Each of the jaws presents a num- ber of deep sockets or ‘alveoli’ which contain the teeth. ( See DISLOCATIONS; FRACTURES; MOUTH; TEETH; also MUSCLES, DISEASES OF; ACTINOMYCOSIS (LUMPY JAW ). Jaw, Diseases of For overshot and undershot jaws, see under TEETH , DISEASES OF. ‘Lion jaw’ (craniomandibular osteopathy): a disease seen mostly in West Highland terriers. Eating becomes difficult; mouth-opening, painful. ( See ‘BOTTLE-JAW’.) Jejunum Jejunum is the central portion of the small INTESTINE. ‘Jeckyll and Hyde’ Syndrome Also known as ‘rage syndrome’, this is a condi- tion seen in cocker spaniels, especially those of a golden or dun colour. For no apparent rea- son a quiet dog will suddenly become very aggressive. The dog then returns to its normal behaviour. Jenny A female ass. Jequirity Poisoning This is caused by the red and black seeds of the climbing plant Abrus precatorius, which grows in Australia, Asia, and South America. It gives rise to cyanosis and pinpoint-sized haemor- rhages from the skin, as well as diarrhoea. Jersian Also known as a F–J hybrid, this is a beef cross obtained from a Jersey bull on a Friesian cow. (In New Zealand, the reverse cross is used.) Jetting Jetting is a technique developed in Australia, involving the application of insecticide under pressure by means of a jetting gun – a handpiece with 4 needle jets for combing through the wool. The pressure used is 10 to 14 kg/cm 2 (60 to 80 lb per sq in), which can be achieved by an ordi- nary medium/high-volume agricultural sprayer. Jetting has not displaced dipping to any extent in the UK, where spraying has been found inefficient in the control of sheep scab. Jigger Flea (see under FLEAS – Tunga penetrans) Jill A female donkey or ferret. Johne’s Disease (Paratuberculosis) Johne’s Disease (Paratuberculosis) is a chronic infection, involving the small and large intestines. It affects cattle particularly, but sometimes sheep, goats, and deer, and is char- acterised by the appearance of a persistent diar- rhoea, gradual emaciation, and great weakness. The infection has been set up experimentally in the rabbit. It may occur naturally in the pig, and post-mortem findings may at first suggest tuberculosis. Cause Mycobacterium johnei (M. paratubercu- losis). Experimentally, sheep can be infected with as few as 1000 M. johnei bacilli. These then mul- tiply in the intestinal mucosa for the first 2 or 3 months after infection. Some animals are able to overcome the infection completely; others become carriers, with the bacilli remaining in the intestinal mucosa and lymph nodes. Some of the carriers eventually become clinically ill with Johne’s disease. Signs The disease is very slow in onset. Cattle that have become infected may not show symp- toms for as long as 2 years after the last case occurred on that farm. Pointers to the disease are an unexplained drop in milk yield (often months before other symp- toms appear); and diarrhoea in an individual adult animal. Loss of condition, general unthriftiness, a harsh, staring coat are then seen, with diar- rhoea. The temperature fluctuates a degree or two above normal. Appetite is variable. In the last stages emaciation becomes very marked, and the animal becomes progressively weaker. In sheep, diarrhoea is not a major symptom. Johne’s Disease (Paratuberculosis) 383 J Treatment When well established, Johne’s disease is invariably fatal, and no treatment is effective or worthwhile. Prevention Attention should be paid to the prevention of infection in other animals, espe- cially calves. Pastures that are suspected of being heavily infected should be left without stock for 4 or 5 months. All infected litter should be stored in a dung-pit which is not accessible to other animals, and should be used for cultivat- ed land. Loose-boxes, sheds, etc., that have housed a case should be carefully disinfected and diseased animals should be fed after healthy ones. Ponds and water-courses should be fenced to prevent fouling by faeces, water for drinking being pumped out. Calfhood vaccination may prevent clinical disease but interferes with subsequent tuberculin tests. Vaccination is being practised in Iceland, the Netherlands, Belgium, and France. In Norway a vaccination campaign to con- trol the disease in goats reduced the infection rate from 53 to 1 per cent. Kids are vaccinated at the age of 2 to 4 weeks. Diagnosis The disease can usually be diag- nosed on clinical evidence, with some confir- mation afforded by microscopic examination of the faeces. Typical clumps of acid-fast bacilli may be found, and the complement fixation test is positive in about 90 per cent of cattle with advanced disease. The fluorescent antibody test is equally useful. Unfortunately, diagnosis of the carrier state is not possible with any certainty. There is no single test which can conclusively detect the presence or absence of M. johnei, although laboratory tests can identify the presence of Mycobacteria spp. The complement fixation test is positive in only a small proportion of carriers and can give false positive results. The difficulty in identifying ‘carriers’ makes Johne’s disease a difficult one to control. Johnin A diagnostic agent derived from M. paratuber- culosis used for JOHNE’S DISEASE. Cutaneous injection results in thickening of the skin in positive cases. While insufficiently sensitive for individual diagnosis, the test is useful for identifying infected herds. Joint-Ill Also called NAVEL-ILL or POLYARTHRITIS, this is a disease of foals, lambs, and calves, in which abscesses form at the umbilicus and in some of the joints of the limbs, due, in the majority of cases, to the entrance of organisms into the body by way of the unclosed navel. There are numerous organisms associated with the dis- ease, the commonest of which are streptococci, staphylococci, Pasteurella, E. coli, the necrosis bacillus, and see under FOALS , DISEASES OF. Signs Usually the young animal becomes dull, takes no interest in its dam, refuses to suckle; the breathing is hurried; the temperature rises from 0.6° to 1.2°C (2° to 4°F) above normal; the foal prefers to lie stretched out on its side, and may have attacks of either diarrhoea or con- stipation. If the navel is examined it is found to be wet and oozing with bloodstained serous material, or it may be dry, swollen, painful to the touch, and hard, owing to abscess formation within. In cases that appear later in life there may be no umbilical symptoms. In the course of a day or so, one or more of the joints swells up. The joints most commonly attacked are the stifle, hip, knee, hock, shoulder and elbow, but it may be seen in any of the others. The swelling is tense, painful, hot, and oedematous. There is the danger of a fatal septicaemia. A chronic form of infection resulting in internal umbilical abscesses is sometimes seen. The primary infection occurs at, or soon after, birth; but once the umbilicus has sealed over, external signs are not evident, and the umbilical remnant appears normal. The calves are usually presented as unthrifty, depressed and slow in their movements. Their temperature invariably normal. Prevention Attention must always be paid to the cleanliness of the foaling-box, the calving- box and the lambing-pen. Where climatic and other conditions are favourable, the pregnant females should be allowed to give birth to their young out of doors. Lambing-pens should with- out fail be changed to a fresh site every year. Investigations undertaken by the Animal Health Trust suggest that thoroughbred foals in the UK suffer severe illness as a result of being deprived of a not inconsiderable volume of blood when the navel cord is severed prema- turely by attendants. Severance of the cord, it seems, is always best left to the mare. The use of strong disinfectants applied to the stump of the navel cord is likewise deprecated. An application of a sulphanilamide or other antibiotic dry dressing may be safer than iodine solution. When cutting the cord, it is necessary to maintain the strictest cleanliness. Scissors should be sterilised, and tape scrupulously clean. 384 Johnin J Treatment Antibiotics and, if available, anti- serum for the causative micro-organisms. Surgically, the umbilicus is opened up, evacuat- ed, and disinfected. Isolation and other hygiene measures are needed. All pails, and other feeding utensils that are liable to get infected, should be thoroughly cleaned using boiling water or steamed before future use, and the pen or box that houses a case should be occasionally washed out with disinfectant. ( See also FOALS , DISEASES OF.) Joints Joints fall into 2 great divisions, namely mov- able joints and fixed joints. In a movable joint there are 4 main structures. Firstly, there are the 2 bones whose junction forms the joint; sec- ondly, there is a layer of smooth cartilage cover- ing the ends of these bones where they meet, which is called ‘articular’ cartilage; thirdly, there is a sheath of fibrous tissue known as the ‘joint capsule’, which is thickened into bands of ‘liga- ments’ which hold the bones together at various points; and finally, there is a closed bladder of membrane, known as the ‘synovial membrane’, which lines the capsule and produces a synovial fluid to lubricate the movements of the joint. Further, the bones are kept in position at the joints by the various muscles passing over them. This type is known as a diarthrodial joint. Some joints possess subsidiary structures such as discs of fibro-cartilage, which adapt the bones more perfectly to one another where they do not quite correspond, and allow of slightly freer movement, e.g. the stifle-joint. In others, mov- able pads of fat under the synovial membrane fill up larger cavities and afford additional protec- tion to the joint, e.g. the hock-joint. In some the edge of one bone is amplified by a margin of car- tilage which makes dislocation less of a risk than otherwise, e.g. the hip and the shoulder-joints. In the fixed joints a layer of cartilage or of fibrous tissue intervenes between the bones and binds them firmly together (synarthrodial joint). This type of joint is exemplified by the ‘sutures’ between the bones that make up the skull. Classified among these fixed joints are the amphi-arthrodial joints, in which there is a thick disc of fibro-cartilage between the bones, so that, although the individual joint is capable of only limited movement, a series of these, like the joints between the bodies of the vertebrae, gives the column, as a whole, a very flexible character. In this connection it is noticeable that the movement in the region of the neck may be much more free than in some of the true movable joints, such as between the small bones of the hock or carpus. Varieties Apart from the division into fixed and movable joints, those that are movable are further classified. Gliding joints are those in which the bones have flat surfaces capable only of a limited amount of movement, such as the bones of the carpus and tarsus. In hinge-joints like the elbow, fetlock, and pastern, movement can take place around one axis only, and is called flexion and extension. In the ball-and-socket joints, such as the shoulder and hip-joints, free movement can occur in any direction. There are other subsidiary varieties, named according to the shape of the bones which enter into the joint. Joints, Diseases of Arthritis means inflammation which involves all the structures of the joint – viz. synovial membrane, capsular ligaments, cartilages, and the ends of the bones that take part in the for- mation of the joint. Arthritis is a general term which includes osteoarthritis and rheumatoid arthritis. Arthritis often begins as a synovitis ( see below), but the degree of inflammation is severe enough to extend to the structures around the synovial membrane. Its causes, symptoms, and treatment are similar to those given for synovi- tis, but it sometimes leads to ankylosis and fix- ation of the joint. ( See CORTISONE.) The joints that are most often affected are the stifle, hock, knee, and fetlocks, but the shoulder, hip, elbow, and the lower joints of the digit are not infre- quently the seat of disease as well. Among dis- eases that are associated with joints, and which are treated separately, are NAVICULAR DISEASE ; SLIPPED SHOULDER; SLIPPED STIFLE; HYGROMA; CAPPED ELBOW; CAPPED HOCK; KNUCKLING OF THE FETLOCK ; JOINT-ILL; see also below and BUR- SITIS; ANKYLOSIS; FRACTURES; DISLOCATIONS; GLASSER’S DISEASE; HIP DYSPLASIA IN DOGS; SWINE ERYSIPELAS. Rheumatoid arthritis This can be impor- tant in the dog, and may occur at any age from 2 years. Symptoms may be vague at first; the animal appears depressed, with a poor appetite and often some degree of fever, but with no lameness. Eventually the latter symptom appears, sometimes involving several joints, sometimes affecting only one limb and then shifting to another. There may be crepitus – a grating sound – when the limb is moved. Diagnosis depends upon radiography and – as in human medicine – there are certain laboratory tests, the results of which provide additional criteria for deciding whether the condition really is rheumatoid arthritis or not. Joints, Diseases of 385 JJ 386 Joule Intractable arthritis of the hip-joint in dogs, as in human beings, may be overcome by major surgery involving removal of the top of the femur and replacement of the ball part of the ball-and-socket joint with a plastic prosthesis. Synovitis is the name given to any inflamma- tion of the membrane lining a joint cavity. It may be acute, sub-acute, or chronic. Generally this is not a separate condition but occurs during the course of rheumatism, rickets, gout (in poultry), severe sprains and bruises, and in a variety of specific infections such as brucellosis, swine erysipelas, tuberculo- sis. Tubercular joint disease often produces a chronic synovitis in the neck bones of the horse, which leads to an arthritis later. Conditions such as wind-galls, curb, bog spavin, etc., are really only synovitis that have become chronic or are complicated with other pathological conditions. The synovial membrane becomes inflamed, thickened, and secretes an excessive amount of fluid into the joint. As a result the joint becomes hot, swollen, and painful. The animal goes lame in greater or lesser degree according to the extent of the inflammation. When at rest, the joint is usually kept flexed with the toe of the affected leg just resting on the ground. If it is a simple condition, such as a mild sprain, these symptoms last for a few days and then gradually pass off. In more severe cases, such as in joint-ill, there may be pus formation, septi- caemia, and death. In the chronic type the swelling persists. The animal is able to use its limb as usual, but the accumulated fluid in the cavity does not disappear (e.g. bog spavin, wind-galls, etc.). Open joint is a condition in which, by acci- dent or other trauma, the inside of the joint is exposed to infection. The seriousness of an open joint is not so much due to the initial injury as to the danger of infection. This may cause tissue destruction with- in the joint, and even lead to a fatal SEPTICAEMIA. The most striking signs of open joint are, first, the excessive degree of pain that seems out of all proportion to the visible amount of dam- age that has been inflicted; secondly, the great amount of swelling that is usually seen; and thirdly, the discharge of a thin, straw-coloured or blood-stained sticky synovia which has a tendency to coagulate around the skin opening. Veterinary advice should be sought at once. Prompt treatment with antibiotics, and surgery if required, is necessary to prevent or limit infection. Dislocations (see main dictionary entry) Bursitis, an inflammation of a bursa, com- monly occurs in the region of a joint. The prominences of the hock, elbow, knee, stifle, etc., are protected by bursae – lined on their insides by synovial membrane. These sometimes become inflamed and lead to the formation of fluctuating swellings which have a tendency to become chronic. Capped elbow, capped hock, and hygroma of the knee, are of this nature. ( See also OSTEOARTHRITIS ; MAST CELLS; OSTEOCHONDROSIS; RHEUMATISM .) Joule A derived SI unit of metabolisable energy. (See CALORIES and STARCH EQUIVALENT , which it replaced; also SI UNITS.) Jugular Veins Jugular veins carry the blood back to the chest from the head and anterior parts of the neck. The jugular vein is often used for taking blood samples and for intravenous injection. The jugular furrow is the groove between the tra- chea and the muscles of the neck, in the depths of which lies the jugular vein. Jungle Fowl (Gallus gallus) A native of the rain forests of South-East Asia, it is the species from which the domestic fowl originated. In its normal environ- ment it prefers hot, humid, shady conditions with frequent rain showers. A broiler-producing company has replicated the climate found in the rain forest in its broiler houses. Mortality was very low and lameness almost non-existent, although the birds took a little longer to reach market weight. Juvenile Cellulitis Also known as ‘puppy strangles’, this condition affects pups between 3 weeks and 4 months of age. The cause is unknown but a hypersensitiv- ity reaction may be involved. Clinical signs are cellulitis on the face and head, prepuce and anus, accompanied by lethargy, anorexia and, possibly, raised temperature. There may be lymphadenopathy. Steroid and antibiotic thera- py is indicated; affected parts may be bathed in aluminium acetate solution. Permanent scarring may result. . mouth-opening, painful. ( See ‘BOTTLE-JAW’.) Jejunum Jejunum is the central portion of the small INTESTINE. ‘Jeckyll and Hyde’ Syndrome Also known as ‘rage syndrome’, this is a condi- tion seen in cocker spaniels,. OF.) Joints Joints fall into 2 great divisions, namely mov- able joints and fixed joints. In a movable joint there are 4 main structures. Firstly, there are the 2 bones whose junction forms the joint;. hinge-joints like the elbow, fetlock, and pastern, movement can take place around one axis only, and is called flexion and extension. In the ball-and-socket joints, such as the shoulder and hip-joints,