Veterinary Services

Generalised and systemic conditions

The complexity of disease situations in some pig units was demonstrated by investigations into increased mortality rate at the 15-week stage on one unit. Some pigs died after an illness of one or two days. Others died following a loss of condition over approximately one week. Three representative pigs were submitted for postmortem examination. One had a clinical history and pathological lesions consistent with postweaning multisystemic wasting syndrome (PMWS) notably, outwith the usual six-to12 week-old age range. Another had typical lesions of porcine dermatitis and nephropathy syndrome (PDNS), with chronic adhesive changes in body cavities consistent with a previous polyserositis. The third pig had a widespread, chronic active bronchopneumonia involving Mycoplasma hyopneumoniae, Streptococcus suis serotype 1/2 and Actinobacillus pleuropneumoniae, complicated by underlying viral-type changes suggestive of PRRS. There was no evidence of underlying PMWS in this pig.

From another unit, four, six-week-old pigs were submitted, two with a history of being found dead, the others lay on their sides trembling. Three of four pigs had septic polyserositis and one had septic polyarthritis. Acute exudative pneumonia with pulmonary consolidation was also present. Actinobacillus suis was isolated from lesions of all pigs, and Streptococcus suis serotype 2 and Haemophilus parasuis were isolated from the lungs of two and three of the pigs respectively. Two weeks later acute Glasser’s disease was also diagnosed in 16-week-old pigs with histories of ataxia, from the same unit. Examinations for underlying PMWS in both age groups showed no evidence of lesions.

On an unrelated unit, an outbreak of Glasser’s disease was diagnosed in a batch of 14 to 16 week old pigs causing five- percent mortality. There was no evidence of underlying PMWS in this instance either.

Alimentary tract disorders

An acute outbreak of diarrhoea in piglets one to two days of age in an indoor breeding unit was associated with type A rotavirus infection. Pathological examinations and comprehensive laboratory investigations refuted initial fears of a failure in the E.coli vaccination programme. The mortality rate in affected litters was in the order of 50 percent.

An outbreak of swine dysentery caused 10 percent mortality in a batch of 120 grower pigs (three-to-four months of age) in a grower-finish unit with a total population of 880 pigs. Diarrhoea spread to all age groups of pigs on the unit but further mortalities were prevented and the disease situation rapidly improved by antibiotic water medication. Cryptosporidia were also detected in the small intestine of two 3 month-old pigs from the outbreak that were submitted for diagnostic confirmation of swine dysentery. Cryptosporidiosis is an unusual finding in pigs in the UK but it was thought to be contributing to the diarrhoea problems in this instance. Investigations into the source of both infections are continuing.

Brachyspira hyodysenteriae, B. pilosicoli, Lawsonia intracellularis and Salmonella species were diagnosed either singly or in various combinations from a number of faecal sample submissions from growing pigs.

Reproductive tract conditions

Ten stillborn piglets from three litters were submitted to investigate a possible adverse vaccination reaction on an outdoor unit. Sows were reported as appearing drunk after administration of an enzootic pneumonia vaccine two weeks pre-farrowing. However sows vaccinated three weeks and one week pre-farrowing appeared unaffected. Findings in the stillborn piglets included fibrinous peritonitis, and intra-abdominal haemorrhage consistent with trauma. Further investigations into infectious causes of stillbirth are underway. The cause of the behavioural changes in the sows remains unexplained.

Musculo-skeletal conditions

A third of a group of 25 homebred gilts became reluctant to stand and exhibited dog sitting eight weeks after housing on straw. One gilt sacrificed for postmortem showed excess serosanguineous joint fluid in both stifles. The joint capsule was dark red with velvety appearance. Mycoplasma hyosynoviae infection was confirmed by culture.