Veterinary Services

Generalised systemic diseases

Three adult sows were submitted from a farm with a longstanding problem of sporadic sudden deaths in sows. Two of the carcases were freshly dead and showed haemorrhages within the lungs and multiple gas bubbles throughout the liver tissue. Clostridium novyi infection was the presumptive diagnosis although attempts to isolate the organism failed. A vaccination programme has started and the outcome will be monitored.

Scour, ill thrift and mortality rates increasing to 10 percent, of weaners on one unit, prompted the submission of three ten-week-old piglets for postmortem. The necropsy findings were consistent with a diagnosis of postweaning multisystemic wasting syndrome (PMWS), indicating that this disease is still causing significant problems.

Neurological diseases

Six pigs within a group of 100 thirteen-week-old gilts in an indoor herd showed signs of scouring and sudden onset neurological signs. The pigs were moved to the building three weeks previously and it was reported that there were no problems with the water supply. The submitted pig showed continuous, convulsive shaking, tremors, chewing movements and ptyalism. Brain cultures were sterile and on neuropathology there was a large influx of eosinophils around the blood vessels in the meninges and brain. In addition there was pseudolaminar cortical necrosis in the cerebrum of the occipital lobe and peracute oedema throughout including watery astrocytes and swollen axons. There were also occasional intense mononuclear inflammatory cell glial foci. The findings were consistent with a diagnosis of water deprivation/salt poisoning.

Streptococcal meningitis was confirmed in two four-week-old piglets from an outdoor herd on the basis of gross postmortem examination and bacteriology. Different serotypes of Streptococcus suis were isolated from each case (type 1 and type 14), indicating that both serotypes were present and causing disease problems in the herd.

Respiratory tract diseases

Acute swine influenza infection with secondary bacterial infection due to Pasteurella multocida type D was confirmed in a four-month-old growing pig from a herd in Sutherland. On gross postmortem examination and histopathology there was an acute interstitial pneumonia with alveolar oedema and haemorrhage. Fibrin exudation and acute necrosis of the bronchiolar epithelium was also noted. Interestingly, there was no report of progressive atrophic rhinitis on the unit.

An indoor slatted unit reported coughing and wasting in a group of 40-kg pigs. The pigs were vaccinated against Mycoplasma hyopneumoniae but the main postmortem finding was of fawny-pink consolidation of the cranial and cardiac lung lobes, suggestive of enzootic pneumonia. Histopathology on this tissue and other areas of pulmonary consolidation indicated complex pneumonic changes including enzootic-type pneumonia (EP), acute bacterial-type pneumonia and viral-type interstitial changes. Streptococcus suis was isolated in culture from the lung. The apparent failure of vaccination to control enzootic pneumonia in this instance is under investigation.

Similarly, four six- to ten-week-old pigs were submitted from a different unit to investigate the cause of an ill-thrift problem that was affecting 20 percent of weaners. The problem had worsened over the previous three weeks. The pigs were vaccinated against Mycoplasma hyopneumoniae at weaning. In this case, all pigs had diffuse viral-type pneumonia, and porcine reproductive and respiratory syndrome (PRRS) was suspected. Two pigs also had evidence of bacterial involvement in the pneumonia and one had evidence of EP. There was no evidence of postweaning multisystemic wasting syndrome (PMWS). PRRS testing was initiated with a view to initiating a vaccination programme.

Alimentary tract diseases

Proliferative enteropathy and acute bacterial type colitis associated with Salmonella Typhimurium were confirmed in a 12-week-old growing pig from a herd with widespread diarrhoea in growers. Further investigation of this herd is ongoing.

Three 12-week-old pigs with chronic diarrhoea were submitted from another finishing unit. A combination of porcine colonic spirochaetosis and PMWS was diagnosed in all three.

Salmonella Typhimurium and Salmonella kedougou respectively were isolated from finishing pigs in a unit that had tested positive for salmonella several weeks previously, despite acidification of the feed after the previous result. More rigorous intervention measures were advised.