Veterinary Services

An investigation into sporadic posterior paresis in adult sows identified a rising antibody titre for talfan/teschen disease in an affected four-year-old landrace cross sow. The clinical history was of a gradual onset of hind limb problems, starting with a slightly abnormal stance and gait, progressing to obvious ataxia and partial or total hind limb paresis over the course of two to three weeks. During the summer of 2010, five sows from the 500 sow unit were affected and were euthanased on account of hind limb paresis and total inability to rise. Postmortem examination on two of the sows showed chronic leucomyelitis with pronounced perivascular lymphocytic cuffing reaction (Figure 6 - see top right-hand side). There was no evidence of encephalitis or of any significant lesions in peripheral nerves, joints or muscles. The sow affected in September of this year was sampled for serology at the early stage of gait abnormality, and again three weeks later when showing partial hind limb paresis. This sow recovered spontaneously over the following three to four weeks. The clinical syndrome from which the sow recovered resembles the talfan type of this disease, also known as benign enzootic paresis that has lower morbidity and mortality than the more virulent teschen type. The virus strains are indistinguishable serologically. As the clinical signs shown by the sows in 2010 were very similar it is possible that these cases were also associated with talfan. Interestingly, there has been no history of hind limb paresis in piglets from this unit. All piglets leave the unit at four weeks of age when they are weaned.

Two outbreaks of meningitis associated with Streptococcus suis serotype 2 were confirmed on separate units. One unit which had been experiencing a high rate of sudden deaths, as well as meningitis like signs in eight-week-old pigs, the other had lost five pigs over the previous seven days.

Porcine dermatitis and nephropathy syndrome (PDNS) was diagnosed in a 15-week-old large white gilt. The animal was noted to have a rash on arrival to the farm aged three months old, yet only one out of a batch of 26 was affected. The skin lesions became progressively worse over a two week period, then the pig became recumbent and died. The diagnosis of PDNS was confirmed by post-mortem examination and histopathology.

Alimentary tract disorders

Two new outbreaks of swine dysentery were confirmed in finishing pigs on unrelated units. In a separate investigation, DNA sequencing was carried out on four Brachyspira hyodysenteriae isolates from separate units as part of a tracing exercise. Comparative sequence analyses showed that three of the isolates were identical whereas the fourth had a number of nucleotide differences suggesting a different source of infection in that unit.