Veterinary Services

Generalised and systemic conditions

One pig was submitted for post mortem examination from a unit where 5 six-week-old pigs had been found dead that morning in the nursery accommodation. The pig was in reasonable body condition with marked hydrothorax with fibrin clots, generalised consolidation of anteroventral lung areas and patchy lobular consolidation of diaphragmatic lobes with some interlobular oedema. Histopathological examination revealed lymphoid changes consistent with post-weaning multisystemic wasting syndrome (PMWS) and viral-type pneumonia. It is not clear whether this case was representative of the others. PMWS had been confirmed on the unit one year ago but until recently the post-weaning mortality had not been excessively high. 

Thirteen deaths out of group of 200 twelve-week-old pigs occurring over a three-day period on a finishing unit prompted submission of a single pig for examination. Dyspnoea and/or cyanosis had been noticed in some of the pigs immediately prior to death. The presence of an extensive fibrinous polyserositis and the isolation of Haemophilus parasuis from lung confirmed the diagnosis of Glässer's disease. Mixing of pigs from two units of different health statuses was considered as the major predisposing factor in this case. The affected pigs were part of a group purchased from a unit that had recently undergone a successful segregated disease control programme (partial depopulation) to eliminate enzootic pneumonia (EP) and porcine reproductive and respiratory syndrome (PRRS), while the other source farm was known to be both EP and PRRS-positive.

Streptococcus suis serotype 1/2 was isolated from the abdominal fluid of a ten-week-old pig subjected to an on-farm post mortem examination in which the gross findings were suggestive of a septicaemia. The farm had experienced previous problems with this serotype, but the reason for this apparent outbreak of cases (nine pigs out of a group of 180 were found dead over a five-day period) was not clear.

Alimentary tract disorders

Rotaviral infection was confirmed as the cause of diarrhoea in four-day-old pigs on one unit. The appearance of the disease in pigs as young as two days of age suggests that early challenge was a key factor. These piglets showed evidence of good colostral immunoglobulin (Ig) absorption, as do many of these early onset cases, and it is likely that infection occurs before substantial quantities of IgA (and in some cases, colostral IgG) are taken in.

A viral-type enteropathy was also diagnosed as the cause of poor post-weaning growth in a six-week-old pig. Although polyacrylamide gel electrophoresis (PAGE) testing of intestinal contents for rotavirus-specific RNA proved negative, the involvement of rotavirus in a post-weaning diarrhoea problem was suspected. No histopathological evidence of PMWS was observed in lymphoid tissues from this animal.

Respiratory tract diseases

Acute pasteurellosis due to Pasteurella multocida was diagnosed in a four-month-old pig. The pig was one of 140 in a straw yard in a finishing unit.  Five pigs from the group had died and coughing was widespread amongst the group, although it is not clear whether this pig was representative of the farm problem. The unit was negative for enzootic pneumonia (a common risk factor) and no histopathological evidence of a viral-type pneumonia was observed in this case. However it is possible that a recent problem with insufficient dietary vitamin E, (reported in December 2004), may have been a predisposing factor.