Veterinary Services

Meningitis due to Streptococcus suis serotype 2 was diagnosed on a unit with ongoing losses due to meningitis and respiratory problems after weaning. Two 11-week-old pigs were submitted for postmortem examination. Both pigs had greyish discolouration of the meninges over the brain stem associated with Streptococcus suis serotype 2. Pasteurella multocida was isolated from the nasal turbinates and from the lung. Enzootic pneumonia-type changes were also evident in the lung on histopathological examination.

Nutritional-type cardiomyopathy was diagnosed in a nine-month-old saddleback gilt, which died suddenly in a small outdoor herd. There was hydrothorax, pericardial effusion, pleurisy and pulmonary oedema. Histopathology revealed irregular areas of degenerative cardiomyopathy, subacute myocarditis and early fibrosis of degenerate fibres. On a separate small-holding, one of a group of six, 12-week-old, Tamworth pigs, all from the same litter, died a week after purchase.  The group was put into a paddock with plenty of grass and some bracken, briars and docken and fed sow rolls and bruised barley.  On-farm postmortem examination revealed a large amount of free fluid in abdomen.  No other gross abnormalities were seen.  Histology of the material submitted revealed extensive damage to the heart and liver consistent with hepatosis dietetica (nutritional hepatic necrosis) due to vitamin E / selenium deficiency.  Dietary advice was provided for the rest of the group. 

Porcine dermatitis and nephropathy syndrome (PDNS) was diagnosed in a five-month-old gilt that died suddenly. The pig was in good body condition but the kidneys were swollen with mild subcapsular petechiation and pale, streaked renal cortices. On histopathology there was diffuse chronic glomerulonephropathy and interstitial nephritis with terminal nephrosis. There was atrophy and sclerosis of the glomeruli.

Interesting histopathological findings were recorded from a five-month-old pig that was found recumbent. As it was unable to rise and walk, it was euthanised for postmortem examination. There was pulmonary congestion and oedema and accumulation of fluid in body cavities suggesting cardio-respiratory failure. There were no other gross changes of note.  On histopathology there were congestive changes in the lung, heart, liver and kidney. The interesting feature was pronounced extramedullary haematopoeisis with many megakaryocytes throughout the parenchyma of the spleen (Figure 5 - see top right-hand side). This suggested significant bone marrow suppression, possibly due to a chronic ongoing toxicity. Records showed that postmortem examinations on a batch of six grower pigs that died on the unit 18 months previously all had similar splenic changes. Investigations into the possible cause are continuing.

Alimentary tract disorders

Scour and weight loss, with 10 per cent morbidity, affected 10-week-old pigs. There were six deaths in one pen overnight. The postmortem findings were of colitis, with liquid brown contents and there were some areas of mucosa with necrotic material adherent. On histopathology of the colon there was widespread mixed inflammatory cell infiltration, mucosal hyperplasia, goblet cell proliferation and mucus accumulation in the crypts. Silver staining revealed large spirochaetes associated with the inflammatory lesions. Brachyspira hyodysenteriae was isolated confirming the diagnosis of swine dysentery.