Veterinary Services

A pig unit experienced four per cent mortality after recently re-stocking with high-health status pigs following total depopulation, thorough cleansing, disinfection and three months vacancy. Sudden deaths occurred in the first batch of growers. Eleven-week-old pigs submitted for postmortem examination showed polyserositis and meningitis was confirmed by histopathology.  Streptococcus suis type 2 was isolated from synovial fluid and meninges. The gilts used for re-stocking were suspected to have been sub-clinical carriers of the infection.

Meningitis was also confirmed in fourteen-week-old finishers, submitted following six deaths in three days. Coughing, sneezing, nervous signs, lameness and lateral recumbency with kicking were reported. One pig had generalised fibrinous pleurisy, pericarditis, peritonitis and polyarthritis. Actinobacillus pleuropneumoniae was isolated from the lung of this pig as the predominant organism in a profuse, mixed growth. Another pig had grey areas of opacity affecting the meninges from which Actinobacillus pleuropneumoniae was isolated. A third pig was identified as having suppurative meningitis on histopathology, though no significant organisms were isolated.

Streptococcus suis serotype 2 was implicated in the sudden deaths of eight of 160 four-month-old pigs. Two pigs were submitted for necropsy. One had fibrinous peritonitis and polyarthritis, highly suggestive of Glasser's disease. However Streptococcus suis was isolated in septicaemic distribution in both pigs.

Erysipelas was diagnosed in two 14-week-old finishers from a group where coughing, sneezing and loss of condition were reported. Cyanotic ears were also seen. Both pigs had a dry, adhesive pericarditis and vegetative lesions on the left atrio-ventricular valves. Most of the leg joints in each case contained excess reddish-brown synovial fluid. Erysipelothrix rhusiopathiae was isolated from the heart valve lesions in each pig.

Alimentary tract disorders

Enteropathogenic E.coli and Salmonella infections were implicated as the cause of ill thrift and scour on two units.  In the first, acute bacterial-type enteritis was seen in two five-week-old pigs from a unit experiencing ill thrift and diarrhoea with a morbidity of ten per cent. A haemolytic, enteropathogenic E.coli was isolated from the intestinal contents of one pig. The histopathological changes were confined to the small intestine where there was loss of surface epithelium and early exudative inflammation suggesting a bacterial insult. Salmonella Typhimurium DT120 was isolated from the intestinal contents of the second pig but only on enrichment. Histopathology on that pig revealed an acute mucosal necrosis of the small intestine and parts of the large intestine associated with bacterial colonisation by Gram negative, rod-shaped bacteria.

Seven-week-old pigs were affected in the second unit and they received apramycin in their water supply. The colonic contents were very watery and E.coli K88 positive and Salmonella Typhimurium DT120 were isolated. Histopathology showed widespread inflammatory cell infiltration in the small intestine and multifocal areas of bacterial colonisation, loss of microvilli and early degenerative changes consistent with an acute bacterial-type insult in the large intestine. Brachyspira hyodysenteriae was detected by PCR in the large intestinal contents but there was no evidence of swine dysentery-type pathology on histopathology suggesting that this may have been an early infection.

Combined infections with Brachyspira hyodysenteriae, Salmonella Typhimurium DT120 and a suspected virus were identified in seven-week-old diarrhoeic pigs. The morbidity was reported to be over 50 per cent with a mortality rate of one per cent. The caeca and colons of two pigs had liquid, gassy contents and the mucosa appeared to be oedematous. Salmonella Typhimurium DT120 was isolated as a scant growth on enrichment in one pig. The histopathological findings were of a severe viral-type enteropathy affecting the small intestine. Brachyspira hyodysenteriae was isolated in culture from the large intestinal contents of both pigs.

Parasitism due to infestation with Trichuris species appeared to be the cause of ill thrift in eight-week-old pigs. The affected pigs were pot-bellied, thin and some scouring was reported in the group. Trichuris worms were seen in the colon and the faecal worm egg count was 5600 eggs per gram. Histopathology of the intestines identified the presence of eosinophils, providing further evidence that parasitism was responsible for the ill thrift.

Respiratory tract disease

An investigation was carried out into coughing in finishing pigs. The mortality rate had increased from three to six per cent over a six month period. The pigs were vaccinated against porcine circovirus 2 (PCV2) and enzootic pneumonia. The lungs of four five-month-old boars submitted for postmortem examination showed consolidation of the cranial lobes with congestion, oedema and haemorrhages. One of the pigs also had a severe septic pleurisy and fibrinous pericarditis. Actinobacillus pleuropneumoniae and Pasteurella multocida were isolated from lung lesions in two and three of the pigs respectively. PCRs for swine influenza and PRRS were negative.