Veterinary Services

Generalised and systemic conditions

Acute erysipelas was diagnosed as the cause of death in six-week-old pigs on a nursery unit where ten pigs out of a group of 200 had died within a 36-hour period. Two of the three pigs submitted for post mortem examination were observed weak and incoordinate and were then found dead within several hours. In two of the animals there was apparent yellow discolouration of carcase fat, but no other significant gross lesions were observed. Steatitis and possible hepatosis dietetica were initially suspected but histopathological examination of tissues revealed only moderate organ congestion with increased numbers of mononuclear cells in hepatic sinusoids, suggestive of a subacute inflammatory process. In a third pig there was gross evidence of pulmonary congestion with some petechial pleural haemorrhages and fibrin tags over the abdominal viscera. Erysipelothrix rhusiopathiae was isolated from the kidneys of all three animals and from the lung of the third pig. It is thought that the minimal pathological changes were a reflection of the peracute nature of the disease in these cases. Erysipelas is generally regarded as an unusual occurrence in pigs of this age and the predisposing factors in this case have not been determined. No further cases have been reported.

A litter of two-day-old piglets was submitted from an outdoor herd which had experienced severe neonatal mortality problems over the previous week. Around 120 out of 400 piglets had died, most of which had been affected within 24 hours of birth. Gross lesions were restricted to the intestinal tract, which showed evidence of marked congestion, and clostridial enterotoxaemia was initially suspected. Heavy growths of E. coli were isolated from the intestinal contents and internal organs of several pigs, consistent with a diagnosis of colisepticaemia. The E. coli isolates were negative for K88 antigen but further serotyping was not performed. Routine vaccination of sows with a combined E. coli and Clostridium perfringens vaccine was initiated.

Respiratory tract diseases

Acute viral-type bronchopneumonia was noted on histopathological examination of lung submitted from a 13-week-old pig. The presence of marked bronchiolar epithelial necrosis was suggestive of swine influenza, although viral isolation was not performed to confirm the diagnosis. Additional histological findings in lymphoid tissues were consistent with underlying post-weaning multisystemic wasting syndrome (PMWS), which had been diagnosed on the unit earlier in the year. This case was the third case among pigs of this age group within one week. All pigs had been "sudden deaths" and were in good body condition, this particular pig showing evidence of cyanosis.