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BOVINE PAPULAR STOMATITIS (BPS) This condition, caused by a parapoxvirus is very common in Britain and other countries. It is characterised by lesions on the nose and in the mouth, and occasionally on the skin. Most cases have minor lesions which do not have any systemic effect on the animal, but in some debilitated animals, lesions in the mouth can become widespread and are then important in differential diagnosis from other diseases. All ages are affected but the young more commonly. INCUBATION PERIOD Uncertain. A calf can develop lesions by 7 days of age. TRANSMISSION AND EPIDEMIOLOGY Virus has been demonstrated simultaneously in pseudo-cowpox lesions on a cow *s teats, and in BPS lesions in the mouths of calves suckling the infected teats. Lesions have occurred in calves several months old which have had no direct contact with older animals, implying that infection might remain dormant in a calf for long periods. The condition is common where there is no contact with sheep, but it seems possible that an off infection might sometimes be the cause of BPS lesions.INCIDENCE The condition is very common and affects mainly calves but is by no means rare in older animals. Adult cows tend to have teat lesions rather than mouth lesions, but they may have both simultaneously or have mouth lesions alone. On examining a group of calves on one occasion it is likely that a small proportion will show lesions. If, however, the animals are examined repeatedly over a long period of time most are likely to show lesions at some time or other. On a farm where calves are seen to be affected it is very likely that some of the dairy cows will have teat lesions. Individual minor mouth lesions are visible for a period of around 1-2 weeks. The mouth may be clear in that time but in a minority of cases successive crops of lesions may last for one to two months. Lesions may recur in an individual animal months or years later. CLINICAL SIGNS
Lesions are confined to nose and mouth with very occasional involvement of the teats and there are no systemic signs of disturbance. Lesions can occur anywhere in the mouth but are more frequent in close proximity to teeth. They are rounded or oval lesions, a few millimetres up to 1.5 cm in diameter with a peripheral red zone of congestion. Within the red zone is a narrow grey/white, often slightly raised, zone. The three zones do not always take a ring form but may be linear alongside the line of the molar teeth. In other sites lesions may not develop in a symmetrical circular form but an arc may extend and in such cases there may be no obvious central necrotic zone. 2. Severe cases These are much less common than the mild form but they tend to occur when an animal is very debilitated from some intercurrent disease, e.g. parasitism in a calf. It is possible that they contribute to death of some animals, but it is impossible to estimate this accurately. Severe lesions tend to be diffuse and irregular in shape, slightly raised slightly roughened and of a yellow or grey colour. When they are most severe there is marked diphtheresis and some consideration may have to be given in a systemically ill animal to differential diagnosis from mucosal disease, foot-and-mouth disease and in some countries, rinderpest. On inspection of BPS cases it may be possible to find a discrete pathognomonic lesion away from the major lesions, and if the animal survives the mouth lesions regress, and it is then often possible to see an underlying basic circular form which may have been obscured a few days previously. Sometimes lesions become complicated by a secondary Fusobacterium necrophorum infection. Severe lesions are associated with wetness around the lips and the tongue may be tender to touch. Circumscribed erosions and ulcers have been found in the skin between the hooves. DIAGNOSIS Many of the lesions are characteristic. It is not necessary to confirm diagnosis in mild cases, but in severe cases it may be important to do so. |
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