Veterinary Services

Ongoing problems of post-natal anaemia of unknown cause continued in a herd.  Nearly all litters have between one and six piglets showing signs of anaemia at birth. In a previous submission of anaemic day-old piglets, reported in December, there were fine scratch-like marks on the head. Histopathology demonstrated an exudative epidermitis and dermatitis associated with deep-seated colonisation by coccal bacteria. From the age and location of lesions, SAC considered that infection occurred in utero, suggesting bacteraemia and placentitis in the sows. Three weeks after including vitamin K in the sow ration the anaemia problem in piglets at birth ceased. Two weeks later the problem resumed although, at least initially, in a less severe form. Two piglets of eight to 12 hours old had packed cell volumes (PCVs) of 0.27 and 0.24 l/l (Reference range 0.37 to 0.46 l/l). Similar linear, scratch-like lesions were present on the heads as in the previous cases. Histopathology, once again, showed bacterial-type epidermitis and dermatitis.

Investigation of sudden deaths in eight-week-old pigs identified Streptococcus suis serotype 2 septicaemia. This was the first time in the recent past that this organism has been identified on the unit. Other units under the same ownership have experienced outbreaks of infection over the previous six months. Ill thrift was reported, affecting younger pigs on one unit. One pig examined had evidence of PMWS on histopathology and another had evidence of enzootic pneumonia-type lesions complicated by bacterial infection, and meningitis.

Alimentary tract conditions

One four-week-old and two eight-week-old pigs were submitted to investigate the cause of scour and increased post-weaning mortality rate. In one of the eight-week-old pigs there were ulcerated, necrotic areas scattered throughout the colon and the large intestinal contents were watery and partially digested. In the other eight-week-old pig the wall of the terminal ileum was thickened. There were ulcerated necrotic areas in the colonic mucosa and a thick layer of yellow diphtheritic material. Histopathology confirmed exudative entero-colitis associated with bacterial infection. Salmonella Typhimurium was isolated in culture from the intestinal contents and appeared to be the only pathogen involved.

In contrast, a nine-week-old pig submitted from a unit with a history of scour and weight loss after weaning was infected with a number of potential enteric pathogens. The lesions were of exudative enteritis and colitis in addition to low-grade lesions of proliferative enteropathy consistent with Lawsonia intracellularis infection in the ileum. Brachyspira hyodysenteriae, Yersinia enterocolitica and Salmonella Rissens were all isolated from the colonic contents.

Scour and loss of condition since weaning were investigated by postmortem examination of a thin, hairy, six-week-old pig. The caecal and colonic serosae had multiple pale nodules and the large intestinal contents were yellow liquid. Brachyspira hyodysenteriae was detected by PCR and in culture. On histopathology there was marked lymphoid depletion of Peyers patches and lymph nodes, highly suggestive of PMWS, in addition to exudative colitis associated with spirochaetal infection.

Faecal samples were submitted to investigate the cause of scouring in sows. Brachyspira hyodysenteriae was identified by PCR in two samples and was isolated in culture from one sow as part of a mixed growth of Brachyspira species. 

Respiratory conditions

Two fattening pigs were submitted from a unit experiencing higher than average mortality. Pleurisy associated with Actinobacillus pleuropneumoniae was identified in pigs from this farm previously.  At necropsy both pigs were in good body condition but had extensive acute pleurisy with pulmonary consolidation (figure 5 - see top right-hand side). Actinobacillus pleuropneumoniae was isolated from lung tissues from both pigs. Pasteurella multocida was also isolated from lung tissue from the second pig.