Veterinary Services

Pathological changes suggestive of post weaning multisystemic wasting syndrome (PMWS) were identified in an investigation into ill thrift affecting four per cent of 500 eight-week-old pigs. The pigs were vaccinated against porcine circovirus 2 (PCV2) at weaning four weeks previously. They were in poor condition and appeared hairy. On histopathological examination the inguinal and mesenteric lymph nodes were depleted with marked loss of lymphoid follicles, low numbers of lymphocytes and early histiocytic infiltrates. The Peyer's patches were also depleted. 
Four seven-week-old pigs were submitted for postmortem examination to investigate the cause of poor post-weaning weight gains. There was also some evidence of scour in the group. The pigs were vaccinated against PCV2 one week before weaning. Tests for Brachyspira species, Lawsonia intracellularis and rotavirus were negative. Histopathology carried out on two pigs showed marked lymphoid depletion. In one pig there was early histiocytic infiltration in the lymph node and spleen and the gut associated lymphoid tissue appeared depleted of lymphocytes. The lymphoid tissue changes were suggestive of PCV2-associated depletion.

Investigation was carried out into a worsening cough affecting 30 per cent of eight-week-old pigs in two pens. There was evidence of enzootic-type pneumonia and varying degrees of chronicity of pericarditis in three pigs submitted for postmortem examination. The only significant bacterial pathogen isolated was Pasteurella multocida from one of the three pigs. The same pig also had evidence of polyarthritis due to Streptococcus suis serotype 2 infection.

Streptococcus suis serotype 2 meningitis was diagnosed in a herd in which there were four sudden deaths in 21-week-old pigs in two days. One pig had grey cloudiness over the cerebellum and in another pig fibrin was present on the cerebellum and brain stem. The latter pig also had severe oedema of the mesocolon. The colonic wall was thickened, congested and the mucosa was friable. The colonic contents were bloody and Brachyspira hyodysenteriae DNA was detected by PCR indicating that swine dysentery was the cause of the colitis.

Blood smears taken from two sows following ten sudden deaths in a group of 26 sows in a farrowing house were inconclusive for the presence of Bacillus anthracis. The local Animal Health Office was informed and samples were submitted to VLA to rule out anthrax. Cultures and PCR tests for B.anthracis were negative. Further investigation suggested electrocution was the cause of death.

Alimentary tract disorders

Excessive looseness of faeces affected twelve-week-old pigs. A typical case with profuse, liquid, mucoid faeces was submitted for postmortem examination. Histopathology provided evidence of diffuse colitis with marked goblet cell hyperplasia of crypts and mucus accumulation. Many bacteria were evident in crypts and in association with the surface epithelium. Silver staining showed many large spirochaetes in the colonic crypts and along the colonic epithelium confirming significant spirochaetal involvement in the colitis.

Two five-week-old landrace pigs were submitted for postmortem examination to investigate lameness and scour affecting a group of 2000 pigs. Soft tissue abscessation due to Arcanobacterium pyogenes was diagnosed as the cause of the lameness. Intestinal histopathology identified coliform attachment in association with mucosal oedema consistent with post-weaning colibacillosis.
A perforated gastric ulcer was the cause of death of a 14-week-old pig. There were three sudden deaths in a group of 200. The pig also had a diaphragmatic hernia resulting in extension of infection into the thoracic cavity.