Sudden deaths and mouth lesions in a Beetal goat unit
A Beetal goat unit in Hisar district has 85 goats, of which 30 are kids. Twenty-two kids were bought from a livestock market three weeks ago without any health certificate. In the last 12 days, 9 kids and 2 adult goats have died. Sick animals show rectal temperature of 40.5–41.5°C, watery nasal discharge, a dry cough in a few, and profuse watery diarrhoea with matted hindquarters. Grey necrotic erosions are visible on the gums, tongue and hard palate. Two kids have crusty lesions at the commissure of the mouth and one has a cloudy eye. The owner has been giving oxytetracycline to the animals still eating and has moved the sick kids into a small shed next to the healthy adults. No vaccination has ever been done on this farm. He plans to sell the remaining kids at the weekly market to cut his losses.
1. Give your differential diagnosis, ranked, stating which findings support or argue against each disease.
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- Peste des petits ruminants (PPR) - most likely. Supports: high fever, watery nasal discharge, cough, profuse diarrhoea, grey necrotic erosions on gums, tongue and palate, high mortality in kids and adults, and introduction of market-purchased kids three weeks earlier, which fits the incubation period. The cloudy eye fits the conjunctivitis of PPR. Nothing argues strongly against it.
- Orf (contagious ecthyma). Supports: crusty lesions at the mouth commissure. Argues against: orf is usually mild, causes no high fever or diarrhoea and rarely kills adults; it may, however, occur together with PPR.
- Contagious caprine pleuropneumonia. Supports: fever, cough, nasal discharge and deaths. Argues against: it is mainly a respiratory disease of adults with severe breathing difficulty, and does not explain the oral erosions or diarrhoea.
- Enterotoxaemia. Supports: sudden deaths. Argues against: usually no fever and no oral erosions; diarrhoea is not typical.
- Coccidiosis. Supports: diarrhoea and deaths in kids. Argues against: no fever of this height, no nasal discharge or mouth erosions.
- Pasteurellosis and plant poisoning should also be considered but fit the whole picture less well.
2. What should be done in the next 24 hours, including whether the remaining kids should be sold?
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Do not sell or move any animal. Sale would spread infection through the weekly market and is also a legal and ethical problem; the animals must be held on the farm.
Immediate actions. Isolate the sick kids in a separate shed away from healthy adults and stop all movement between the two groups. Inform the nearest veterinary dispensary at once, because PPR is a notifiable disease. Provide supportive care: oral rehydration solution, water and palatable green fodder, a NSAID for fever, and an antibiotic only to control secondary bacterial infection in animals still eating; oxytetracycline alone will not cure PPR. Disinfect the shed, feeders and waterers, and bury or incinerate carcasses away from the water source. Restrict visitors and vehicles. Collect samples from freshly dead or sick animals before treatment. Ring vaccination with PPR vaccine should be discussed with the veterinarian: healthy in-contact animals can be vaccinated, but sick animals should not be. Keep a record of all deaths and treatments so that the outbreak can be traced.
3. Which post-mortem findings and laboratory samples would support a diagnosis of PPR?
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Post-mortem findings: erosions and grey necrotic plaques in the mouth, pharynx and oesophagus; similar lesions and congestion in the abomasum and small intestine; prominent Peyer's patches with necrosis; enlarged, congested mesenteric lymph nodes; heavy congested lungs with areas of consolidation; enlarged spleen; and congestion of the conjunctiva. These lesions are suggestive but overlap with other diseases, so laboratory confirmation is essential.
Samples: collect spleen, mesenteric lymph node, lung and affected intestine in both 10% formalin for histopathology and a sterile container kept refrigerated for virus detection. Take conjunctival and nasal swabs in virus transport medium. Submit blood from acutely ill and recovering animals for serology. Label each sample with the animal number and date, keep it cold but not frozen, and send it through the veterinary authorities. Rapid tests such as RT-PCR or antigen ELISA on conjunctival swabs and lymph node are the practical confirmatory methods.