Veterinary Services

Respiratory tract conditions

Submissions in March were dominated by outbreaks of respiratory diseases. Porcine reproductive and respiratory syndrome (PRRS) was diagnosed as the cause of poor growth and respiratory signs in weaned pigs in a unit that vaccinated at weaning against circovirus. The herd was enzootic pneumonia (EP) free and positive for PRRS but had no vaccination programme in place for the latter. There was consolidation of the cranio-ventral lung lobes. Glasser’s disease was suspected by the submitting veterinary surgeon on the basis of a postmortem examination was carried out on one pig on farm, but Haemophilus parasuis was not cultured from a pericardial swab. Histopathology provided evidence of a chronic suppurative pneumonia in the three pigs which were sampled. The PCR for Mycoplasma hyopneumoniae was negative, but the PCR for PRRS was positive on lung tissue. There was also evidence of a mild colitis in one of the pigs.

Multiple pathologies were identified when three, four-month-old pigs were submitted to investigate an increased mortality rate on a holding. The pigs lost condition and died. A programme of circovirus vaccination of weaners had been temporarily stopped. The pigs had received tylosin for the previous month but without improvement. All three pigs had fawn-coloured consolidation of the cranial and intermediate lung lobes and dry pleuritis with adhesion of the lung lobes to the thorax. The pigs were vaccinated against EP but the gross findings suggested this disease. One pig also had evidence of bacterial pneumonia with multiple abscesses in the cranial lung lobes. Arcanobacterium pyogenes and Streptococcus suis serotype 7 were isolated from the lung of this animal. The pigs had slightly loose faeces and Yersinia pseudotuberculosis was isolated in culture from the intestinal contents of one of the pigs. On histopathology all three pigs showed changes consistent with postweaning multisystemic wasting syndrome (PMWS). Changes typical of enzootic-type pneumonia were also confirmed. The pig from which the Y. pseudotuberculosis was isolated had evidence of a bacterial-type colitis.

Sudden deaths of ten 14-week-old gilts over a two-day period was investigated by submission of three for postmortem examination. All three gilts examined showed a severe unilateral fibrinous pleurisy and pneumonia, with almost complete consolidation of the pulmonary tissues. Some localised consolidation was present in the other lung. A fibrinous pericarditis was also present. Bacterial culture of affected tissues yielded Actinobacillus pleuropneumoniae and Pasteurella multocida. Serotyping of the A. pleuropneumoniae found that serotypes 3, 6 and 8 were involved. These serotypes can show a high degree of cross-reactivity.

Two 12-week-old pigs from a rearing unit were submitted having both been found dead on the same morning. Postmortem examination of the first pig revealed extensive mottling of the lung parenchyma and suppurative bronchopneumonia affecting the antero-ventral lung lobes. There was generalised congestion of carcase organs but otherwise, no findings of note. Culture of lung tissue from both pigs yielded growth of Pasteurella multocida, while Streptococcus suis was also isolated from one of the pigs. Histopathological examination of lung tissue from both pigs found suppurative bronchopneumonia with extensive viral-type changes also present in non-consolidated tissue.

Musculo-Skeletal conditions

The sudden onset of lameness was reported in a batch of 90, 70-80kg organic pigs three weeks after transfer to a finishing unit. The morbidity rate was 22 per cent. Only the right foreleg was affected in all the pigs except for two where the left fore was involved. Swelling and bleeding was apparent at the coronary band and the hoof of some pigs was about to detach. The pigs were bright and lively and had performed well. Postmortem examination of one pig revealed proliferative granulation tissue halfway up the anterior surface of the medial digit of the right fore and extending beyond the coronary band. There was massive tissue damage subcutaneously and surrounding the tendon sheaths with oedema and granulation tissue formation throughout the interstitial tissue. Another pig had similar changes but was less severely affected. The joints were unaffected. Trauma was suspected though the stockmen was unable to identify the cause. Histological features such as fibrosis and collagen deposition within the granulation tissue indicated that these were not acute cases.

A necropsy was performed on an adult boar that was found dead with no prior signs of illness. Examination revealed a mild dilatation of the right side of the heart, and generalised congestion of all organs but no macroscopic lesions of note. Histopathological examination of the lung showed marked diffuse congestion and oedema but no appreciable inflammatory or degenerative changes. The myocardium showed separation of myocardial fibres suggesting myocardial oedema, with hypoxic-type changes to myofibres but no evidence of degenerative cardiomyopathy. While the findings suggested an acute congestive heart failure unfortunately the cause was not apparent. A physiological problem involving conduction mechanisms within the heart was postulated.

Parasitic diseases

Parasitological examination of faecal samples from two sows in poor condition revealed significant numbers (600 and 800 epg) of Hyostrongylus rubidus worm eggs.