Veterinary Services

Glasser’s disease (Haemophilus parasuis infection) was diagnosed on postmortem examination of a fourteen-week-old finisher from a herd in Morayshire. Dyspnoea, pyrexia and nervous signs had been noted in the growing and finishing groups. Morbidity was high (40 percent) but antimicrobial treatment kept mortality low (one percent). Despite treatment approximately five percent of the pigs remained chronically affected.

Alimentary tract disorders

An outbreak of diarrhoea with a mortality rate of five percent was reported in a batch of eight-week-old pigs. Of three typical cases submitted for postmortem examination, two had yellow fluid contents in small and large intestines. The third pig had greyish and semi-fluid intestinal contents. Histopathology showed widespread coliform attachment to the surface epithelium of small and large intestinal tissues. The surface epithelial cells showed early degenerative changes. The findings were consistent with a pathogenic Escherichia. coli and suggested an attaching/effacing process. One pig also had postweaning multisystemic wasting syndrome (PMWS)-type changes in the lymph nodes.

Ill thrift and diarrhoea were reported in eleven-week-old pigs on a unit. Two pigs were submitted for postmortem examination. In one the large intestine was thickened and oedematous. The mucosa was hyperaemic and the contents were liquid and green. There was a thick layer of white mucus adherent to the mucosa. The changes in the other were similar but the caecal contents were reasonably firm and there was less mucoid material present. Histopathological examination confirmed the presence of a chronic active typhlocolitis associated with spirochaetal bacteria suggestive of Brachyspira pilosicoli.  In addition there was evidence of enzootic type pneumonia and in one of the pigs of a necrotising bacterial pneumonia.

Brachyspira pilosicoli was identified by PCR and on culture of faecal samples from an unrelated  large grower unit. The unit had a recent history of reduced growth rates and loose faeces affecting approximately 30 percent of pigs. No other enteropathogens were detected by routine laboratory tests.

An investigation into the possible causes of poor growth rates in a large finisher unit had shown a high proportion of faecal samples to be positive for Lawsonia intracellularis DNA by PCR testing.  No other enteropathogens were detected. Three pigs were examined postmortem and the diagnosis was confirmed prior to embarking on a vaccination programme against this agent.

Respiratory tract conditions

Serology for Mycoplasma hyopneumoniae was carried out on growing pigs on a unit to investigate a suspected enzootic pneumonia (EP) breakdown. Lesions had been detected through the Wholesome Pigs monitoring scheme at slaughter. Seventy-five percent of the samples were antibody positive in the Mycoplasma hyopneumoniae ELISA test, confirming the slaughter observations.

The carcases of three finishing pigs in the age range of 15 to 19 weeks were submitted after ten animals were found dead in one grow-out unit. The owner reported a rising mortality rate in recent weeks, as well as coughing and reduced feed intake.  Pleuropneumonia due to Actinobacillus pleuropneumoniae was known to be present on a related unit approximately three miles away. By applying suitable movement and biosecurity measures it was hoped that the grow-out would remain free from this infection. Necropsy confirmed fibrinous pleurisy, pneumonia and pericarditis of varying severity. Bacterial cultures and histopathological examinations confirmed that this grow-out had indeed broken down with pleuropneumonia.

Bacterial bronchopneumonia and pleurisy due to Pasteurella multocida and Streptococcus suis serotype 14 infections were diagnosed on a finishing unit. The unit had experienced an increased mortality rate and coughing over the previous two weeks. Some of the pigs were vaccinated against EP but others were not. There was a limited response to tylosin treatment. Four 24 to 25-week-old pigs were submitted. Streptococcus suis serotype 14 was isolated from the lung of one pig that had evidence of bronchopneumonia. Pasteurella multocida was isolated from the lung of a pig with necrotic pleuropneumonia and also from a pig where the gross findings were of a bacterial pleuropneumonia. A third pig had severe bacterial type pneumonia with chronic pericarditis and arthritis but cultures were sterile. On histopathology all pigs showed similar lung lesions. These were of acute severe focally extensive suppurative and necrotising bronchopneumonia and fibrinous pleurisy consistent with a bacterial aetiology. There was no evidence of EP involvement at postmortem examination or on histopathology.

Nervous diseases

A four-month-old gilt was the fourth pig to show nervous signs over a short period of time. It was submitted alive and was in lateral recumbency with intermittent paddling. At postmortem examination, the meninges were cloudy and the meningeal vessels injected. In addition there was an excess of yellow synovial fluid in the elbows, shoulders, stifles and hock joints. Streptococcus suis serotype 2 was isolated in culture from the meninges, liver and the joints consistent with a streptococcal septicaemia.

Streptococcus suis serotype 2 meningitis was diagnosed on another unit where three pigs showed central nervous signs over a three day period. The third case, submitted alive, was unable to stand and was shaking. At postmortem examination there was evidence of a subacute to chronic pleurisy, pneumonia and pericarditis. The meninges were visibly thickened and discoloured. Streptococcus suis serotype 2 was isolated from the brain and pericardium but not from the lung or systemic cultures. Neuropathology confirmed the presence of a diffuse suppurative meningitis occasionally infiltrating the nervous tissues.