Veterinary Services

A lack of colostrum and neonatal Staphylococcus hyicus dermatitis were identified as causes of piglets fading and dying at one to two days of age. Two of three representative piglets submitted for postmortem examination had zinc sulphate turbidity (ZST) values of one and three units respectively (reference value >15 units), suggesting poor colostrum absorption due to hypoglycaemia or starvation. A third piglet received adequate colostrum (ZST value 33 units) but had severe bilateral epidermitis and dermatitis affecting the face which made it unwilling to suckle. SAC C VS considered these findings highlighted problems with farrowing house management and hygiene.

Joint ill associated with Staphylococcus aureus was diagnosed in multiple litters of piglets at approximately two weeks of age. The piglets were reluctant to stand and had obvious carpal swelling. Postmortem examination showed bacterial-type polyarthritis affecting the carpal and elbow joints, with early cartilage erosion in the carpi. Although the source of infection was not determined, attention to hygiene during management procedures was advised.

Three outbreaks of meningitis and bacteraemia associated with Streptococcus suis type 2 infection were diagnosed. The units were unrelated and the outbreaks affected pigs at eight, 15 and 20 weeks of age respectively. All outbreaks had typical histories of ‘sudden deaths’ or pigs that were ataxic, shaking and hyperpnoeic progressing to recumbency and paddling. In the largest outbreak, 57 pigs died in a unit with 20-week-old pigs. In that outbreak, SAC C VS considered that high humidity in the shed contributed to the overall severity.

A combination of diseases was diagnosed among 18-week-old pigs submitted from a unit where 19 pigs died in the previous 24 hours. Clinical signs included diarrhoea, ill thrift, coughing, jaundice and subcutaneous oedema.  Postmortem findings and subsequent diagnostic testing identified the presence of hepatosis dietetica as the cause of jaundice, subcutaneous oedema and polyserositis. A combination of enzootic pneumonia and swine dysentery was confirmed in the cases showing ill thrift and diarrhoea.

Alimentary Tract Conditions

Outbreaks of swine dysentery due to Brachyspira hyodysenteriae were diagnosed in seven unrelated units involving weaners, growers and in one instance sows. The outbreak affecting the youngest pigs (seven weeks of age) was complicated by co-infection with a group C Salmonella species. The morbidity rates for these outbreaks were between five and ten per cent. In the outbreak involving adult pigs, the history was of an acute onset of vomiting and diarrhoea in a batch of two-year-old sows. One died and the diagnosis was confirmed by postmortem examination. One outbreak in growers was attributed to having received pigs from a breeding herd subsequently diagnosed as having swine dysentery. The source of infection for the other six outbreaks was unknown.

Two outbreaks of porcine colonic spirochaetosis due to Brachyspira pilosicoli occurred on unrelated units, causing diarrhoea and poorer growth rates in approximately ten to 15 per cent of pigs. Postmortem examination showed typical lesions of chronic colitis, with the presence of the agent confirmed by PCR test and culture.

An investigation into the cause of acute onset diarrhoea and weight loss in a batch of six-week-old piglets was attributed to an intestinal attaching E.coli infection. Histopathological examination of intestinal tissues showed widespread coliform attachment to the surface epithelium, villus oedema and early epithelial degenerative changes. The ileum was most severely affected. The piglets were weaned two weeks before the start of the outbreak.

Thirteen deaths over seven days were reported in finishing pigs which were on the unit for ten weeks. Meningitis was suspected as the history involved ‘sudden deaths’ and other pigs found recumbent and shaking, but which died before any treatment could be given.  Postmortem examinations found torsion of the small intestine around the root of the mesentery with typical intense generalised deep purple intestinal congestion with haemorrhagic contents. There was no evidence of meningitis. Pigs were on ad lib concentrate feeding and there were no apparent changes to the feed or feeding system. It was unclear what factors initiated this outbreak of torsions.