Veterinary Services

Alimentary tract disorders

An organic unit with a recent history of post weaning multisystemic wasting syndrome (PMWS) changed the vaccination regime for piglets by replacing ileitis vaccine with circovirus vaccine. Enzootic pneumonia vaccination of piglets was retained. The first batch of 250 weaners coming through after the change in vaccination regime saw the rapid loss of condition of eight 13-week-old pigs. There was also evidence of loose faeces. The eight affected pigs submitted for postmortem all showed thickening of the terminal ileum and one pig had necrotic enteritis. Porcine proliferative enteropathy was confirmed on histopathology. There was no evidence of PMWS.

Ill thrift affected about 10 per cent of a group of 200 seven-week-old pigs. Another unit with pigs from the same source reported 10 per cent morbidity and four per cent mortality in nine-week-old pigs also associated with ill-thrift. PMWS was suspected. Postmortem examination revealed typhlocolitis with green, slightly mucoid large intestinal contents. On histopathology there was an increase in lymphocytic cells in the large intestinal mucosa, goblet cell hyperplasia in crypts and inflammation associated with bacterial colonisation. On silver staining large, fine spirochaetes were detected which was consistent with a diagnosis of porcine colonic spirochaetosis. There was no evidence of PMWS on histopathological examination of lymphoid tissues. Circovirus vaccination was not used in this instance.

Acute neonatal colibacillosis complicated by clostridial infection was diagnosed in an outdoor-farrowing herd that reported deaths in neonatal piglets. A beta-haemolytic E.coli was isolated from the ileal contents of one five-day-old piglet and Clostridium pefringens was isolated from the small intestinal contents of this pig and another piglet. On histopathology the two piglets had widespread and prolific coliform attachment to the villus epithelium, with acute necrosis of the villi associated with Clostridial-type bacteria. Combined infections were thought to be implicated in the outbreak. There was no E.coli or Clostridial vaccination of sows on the unit.

Trends in pig respiratory diseases in Scotland between 2003 and 2007

The diagnoses of pig respiratory disease outbreaks between 2003 and 2007 are indicated in Table 1 (see Figure 2 top right-hand side). The data indicates the causes of new outbreaks and the trend has been fairly consistent over the years. Respiratory diseases have comprised between 19 and 25% of the diagnosable porcine submissions annually, with the highest proportion occurring in 2007. Of those with specific aetiological diagnoses, bacterial causes including Pasteurella multocida, Haemophilus parasuis and Actinobacillus pleuropneumoniae predominated, along with Mycoplasma hyopneumoniae. The highest percentage of diagnoses (approximately 7 - 8%) fell within the category of pneumonia NOS, reflecting the presence of pneumonia where no specific cause was identified. This category was comprised primarily of viral-type pneumonias where no specific diagnosis was possible owing to the lack of porcine virus isolation and immunohistochemistry facilities within SACVS. Also included were bacterial-type pneumonias where no isolate was achieved due to antimicrobial treatment prior to submission. Cases with pathological lesions of postweaning multisystemic wasting syndrome (PMWS) that also had viral-type pneumonia suspected to be caused by porcine circovirus type 2 (PCV2), could not be coded as such as the pulmonary changes are not specific for PCV2 and we were unable to confirm the presence of virus in lung lesions. Therefore such cases are not reflected in this data set.

An indication of the national prevalence data relating to pneumonia and pleurisy in finishing pigs is provided by the Wholesome Pigs Scotland abattoir monitoring scheme.  Currently, this shows gross lesions suggestive of enzootic-type pneumonia in approximately 45% of herds, significant pleurisy in approximately 25% of herds and snout lesions suggestive of atrophic rhinitis in around 3% of monitored herds.

The distribution of Mycoplasma hyopneumoniae and Porcine reproductive and respiratory virus outbreaks between 2003 and 2007 are shown in Figure 3 (see top right-hand side). The distribution broadly matches the area map of pig density in Scotland.