Veterinary Services

Generalised and systemic conditions

A 70 kg pig, found dull and recumbent on a finishing unit, was submitted for post mortem examination following euthanasia on the farm. An increase in "sudden" deaths among pigs in good body condition had been reported, with 18 deaths out of a group of 2000 recorded over a four-day period.

Gross examination revealed generalised lymph node enlargement, pallor and oedema. Both kidneys were markedly enlarged with cortical pallor and mottling. Widespread severe glomerulonephropathy with hyaline cast formation, consistent with a diagnosis of porcine dermatitis and nephropathy syndrome (PDNS), were noted on histopathological examination. The lymph nodes showed evidence of oedema and acute necrosis, a frequent finding in cases of PDNS and thought to be secondary to acute toxaemia. The significance of this case to the other reported deaths on the unit is not clear.

Alimentary tract disorders

Severe scour was reported in three of a group of eleven twelve-week-old pigs recently transported from the mainland to Shetland. Histopathological examination of colon from one of the pigs, euthanased in extremis, revealed widespread inflammation with mononuclear cell infiltration and excess crypt mucus. Gram and silver staining of sections showed mixed bacterial infection in the crypts and the presence of large numbers of spirochaetes. Brachyspira pilosicoli-specific DNA was detected by polymerase chain reaction (PCR) and Yersinia enterocolitica was isolated on bacteriological culture. The findings were consistent with a mixed bacterial colitis. Possible precipitating factors include the stress of transport and post-weaning multisystemic wasting syndrome (PMWS), tests for which were not performed.

Porcine proliferative enteropathy (PPE) was confirmed as the cause of scour in twelve-week-old pigs on an organic unit. In the two cases examined, the large intestinal pathology appeared more marked than the ileal pathology. A third pig examined showed no evidence of PPE but histopathological examination revealed evidence of mild spirochaetal colitis. Although the lesions were not typical of acute swine dysentery, the findings were complicated by the detection of Brachyspira hyodysenteriae-specific DNA on PCR testing of pooled faeces from the three pigs. Strains of B. hyodysenteriae with a lower intrinsic virulence are known to be present in Scotland and it is possible that this case involves such an isolate.

Respiratory tract diseases

Mycoplasma hyopneumoniae-specific DNA was detected by PCR from a lung sample taken at the abattoir where lesions suspicious of enzootic pneumonia had been observed during routine quarterly inspections under the Wholesome Pigs Scotland monitoring scheme. Widespread coughing had been noticed in the finishing accommodation on the high health unit concerned, and the problem appears subsequently to have spread to growing pigs. The source of the breakdown is not known.

Nervous system diseases

A seven-week-old male piglet from a pen of ten weaned at four weeks of age was submitted for post mortem examination. There was no history of illness in the group and this pig had been found dead unexpectedly. Gross examination revealed generalised congestion and sparse gastrointestinal contents. The meninges were markedly congested and sub-meningeal oedema was evident. Histopathological examination confirmed the meningeal congestion and oedema and revealed a moderate, mixed inflammatory cell infiltrate consistent with subacute meningitis. There was also lymphoid depletion in lymph nodes suggestive of subacute PMWS. Bacterial culture of the meninges yielded a mixed growth of E. coli, Proteus spp. and Staphylococcus epidermidis. It seems likely that these isolates represent opportunistic infections secondary to the immunosuppressive effects of the PMWS.

Suppurative meningitis and polyarthritis were noted during examination of a 20kg pig from a nursery unit reporting a problem of occasional arthritis and some "sudden" deaths. Many of the arthritis cases had responded to parenteral amoxycillin therapy. This pig had been discovered in lateral recumbency showing paddling movements and had been treated with antibiotic immediately prior to succumbing. A scant growth of Streptococcus suis was isolated from the brain but the autoagglutinating properties of the isolate prevented serotyping.