dich ta lon ppt

CHAPTER 4 SPECIFIC DISEASES OF PIGS Diseases caused by viruses African Swine Fever (ASF) ASF is a highly contagious viral disease of domestic pigs manifested by fever, blotching of skin, haemorrhage of the lymph nodes, internal organs and haemorrhage of the gastrointestinal tract. It is observed in acute and occasionally subacute and chronic forms. Transmission : There is a natural cycle of the ASF virus between bush pigs, warthogs and giant forest hogs and some tick species (Ornithodorus) in which the virus replicates. The spread of the virus is by contact with affected pigs and infected fomites, ingestion of contaminated uncooked pork garbage, tick bites and contact with domestic and wild carrier pigs. The virus is quite resistant to cleaning and disinfection. It survives for 2 – 4 months in an infected premises and 5 – 6 months in infected meats. The virus can survive in smoked or partly cooked sausages and other pork products. Humans are not susceptible to this disease. Antemortem findings : 1. Incubation: 3 – 15 days 2. Fever (up to 42°C) 3. Laboured breathing, coughing 4. Nasal and ocular discharge 5. Loss of appetite and diarrhoea 6. Vomiting 7. Incoordination 8. Cyanosis of the extremities and haemorrhages of skin 9. In chronic stage, emaciation and edematous swelling under the mandible and over leg joints 10. Recumbency Postmortem findings : 1. Blotchy skin cyanosis and haemorrhage (Fig. 113) 2. Enlarged spleen (splenomegaly, Fig 114) 3. Petechial haemorrhage on the kidneys (Fig. 115) 4. Enlarged and haemorrhagic gastrohepatic and renal lymph nodes 5. Haemorrhage in the heart 6. Hydrothorax, hydropericardium and ascites 7. Haemorrhage of the serous membranes 8. In chronic ASF pericarditis, and emaciated carcass Judgement : Carcass of an animal affected with African Swine Fever is condemned. The animal is prohibited from entering the abattoir. Differential diagnosis : Hog cholera, salmonellosis, erysipelas, Glasser's disease (Haemophilus suis) infection Fig. 113: African swine fever. Blotchy skin, cyanosis and haemorrhage. Fig. 114: African swine fever. Enlarged spleen (splenomegaly). Fig. 115: African swine fever. Petechial and ecchymotic haemorrhage in the kidneys. Note haemorrhagic areas in the renal pelvis and papillae. Foot and Mouth Disease (FMD, Aphthous fever) FMD is a contagious, viral disease of swine, cattle, sheep, goats and pigs and other cloven footed animals. The disease in pigs is mild and is important as being a potential danger for transmission to cattle. Transmission : Direct and indirect contact with infected animals. The virus can also be spread by aerosol, saliva, nasal discharge, blood, urine, faeces, semen, infected animal by-products, swill containing scraps of meat or bones and by biological products, particularly vaccines. Pigs can transmit the disease to cattle and other animals. Antemortem findings : 1. Incubation 3 – 15 days. Pigs that are fed food wastes contaminated with FMDV may show signs of infection in 1 – 3 days. 2. Snout (Fig. 116) and tongue lesions very common in pigs 3. Dullness and lack of appetite 4. Salivation and drooling 5. Detachment of the skin on a pig's foot (Fig. 117) 6. Shaking of feet and lameness due to leg lesions Some strains of FMD in swine do not show vesicles but show erosions. Judgement : Feverish animals with associated secondary bacterial infections call for total condemnation of the carcass. The meat of suspect animals may be conditionally approved after deboning, and condemnation of the head, feet, viscera and lymph nodes of the carcass. Such meat must be thoroughly cooked and could be used as canned meat. Differential diagnosis : Swine vesicular disease, vesicular stomatitis and vesicular exanthema in pigs can be differentiated from FMD only by laboratory testing. Fig. 116: FMD. Vesicle on the snout in a pig. [...]... Transmission : Infected swine, excretions, ingestion of contaminated uncooked pork wastes, minor skin wounds The shedding of the virus begins before the appearance of clinical signs and may continue for up to 3 months This virus is more resistant to disinfectants and environmental conditions than the FMD virus The SVD virus is acid stable and was isolated from certain type of sausage prepared from infected pork... regions It causes fatal infections in a significant proportion of infected humans, especially those who are immuno-compromised or have intercurrent disease Transmission : Infection occurs by ingestion of the infective material containing Pseudomonas pseudomallei, contamination of wounds or abrasions of the skin or perhaps bites of insects Important sources of infection are rodents, contaminated swamps... secretion in sows Postmortem findings : 1 Distended intestine with fluid ingesta (Fig 125), thin translucent intestinal wall 2 Degeneration of heart muscle and rarely skeletal muscles 3 Microscopical villous atrophy of intestine (Fig 126) Fig 125: TGE Distended intestine showing translucent intestinal wall and fluid ingesta Fig 126: TGE Villous atrophy of intestinal mucosa Judgement : A slightly affected... Enteritis 5 High fever lasting 12 – 24 hours 6 Severe watery diarrhoea and dehydration 7 Pneumonia 8 Emaciation and death 9 A sequel to enteric salmonellosis may be rectal stricture 10 Abdominal dilatation and frothy to pasty faeces in cases of rectal stricture Postmortem findings : Septicemic syndrome 1 Discoloration of the skin 2 Enlarged and engorged lymph glands 3 Haemorrhages, petechiae and ecchymosis... Marked skin haemorrhage Prominent petechial haemorrhage in the kidneys Chronic enteritis 1 2 3 4 Areas of necrosis in the wall of the caecum and colon Enlarged mesenteric lymph nodes Chronic pneumonia Abdominal dilatation and low grade peritonitis in cases of rectal stricture Judgement : Viscera and carcass affected with salmonellosis are condemned In some areas the heat treatment of the carcass is recommended... transmission is not completely known Biting flies and mosquitoes, direct contact between the animals and droplet infection are possible ways of transmission Antemortem findings : 1 2 3 4 5 6 7 Incubation 2 – 4 days Fever Lesion on the tongue (Fig 124) and snout Lesion in the interdigital space or coronary band Refusal of food but acceptance of water Weight loss Lameness and exungulation Judgement : Carcass... common contact and via air Mycoplasma hyopneumoniae is not isolated from the respiratory tract of healthy animals It persists in chronic lung lesions of recovered animals and is a source of infection particularly for the new animals in the herd Actinobacillus (Haemophilus) pleuropneumoniae is found in the nostrils and lungs of healthy animals An outbreak of the disease may be triggered by environmental stresses... An outbreak of the disease may be triggered by environmental stresses Antemortem findings : Enzootic pneumonia: 1 Mortality may occur, but is very low 2 Fever is usually absent 3 Acute respiratory distress and a characteristic dry cough when excited Chronic form: 4 Dry hacking cough 5 Retardation in growth Pleuropneumonia: 1 2 3 4 5 Fever ( 41°C) Respiratory distress Bluish appearance of mucous membranes... influenza, rhinitis, Ascaris suum infestation, laryngitis, tracheitis, pulmonary edema and congestion, injuries and tuberculosis Fig 127: Pneumonia Enzootic pneumonia Lung lesions affecting anterior and bottom portions of the lungs Fig 128: Chronic pneumonia with abscessation This pneumonia was caused by Mycoplasma spp and later infected with secondary bacteria A beta-haemolytic Streptococcus was isolated... Escherichia coli Bacteraemia caused by infection in some remote organs, muscle or bones may be associated with a lesion in the endocardium The valves are the most frequently affected Emboli may detach from friable vegetation on the valves and pass through the blood stream to organs and cause infarcts Emboli from the right heart are a frequent cause of pulmonary abscessation or pulmonary thrombosis Antemortem . by contact with affected pigs and infected fomites, ingestion of contaminated uncooked pork garbage, tick bites and contact with domestic and wild carrier pigs. The virus is quite resistant. contact with infected pigs and ingestion of uncooked contaminated food wastes containing infected pork scraps. Antemortem findings : 1. Incubation 5 – 10 days 2. Morbidity 40 – 100 % 3. Mortality. This virus is more resistant to disinfectants and environmental conditions than the FMD virus. The SVD virus is acid stable and was isolated from certain type of sausage prepared from infected