Veterinary Services

Generalised and systemic conditions

No new outbreaks of post-weaning multisystemic wasting syndrome (PMWS) were reported this month, although upsurges in problems associated with the disease were noted on several units. On two units reporting increased scour in ten to fifteen-week-old pigs, examination of affected animals revealed characteristic histopathological lesions of PMWS together with lesions of non-specific bacterial-type colitis. No significant enteropathogens were isolated/detected in either of these cases.

The detection of multiple, white cyst-like lesions in the heart of a six-month-old wild boar during routine post mortem meat inspection raised initial concerns of the possibility of Cysticercus cellulosae (the intermediate stage of the tapeworm Taenia solium), which has not been reported in the UK for many years. The lesions were up to five millimetres in diameter with an apparent fibrous white capsule and contained clear viscous fluid with white flocculent material. Histopathological examination of the lesions revealed evidence of chronic abscessation and mineralisation. Bacterial colonies showing peripheral "club" formation were present within the lesions, suggestive of Actinobacillus spp. infection. Although bacteriological culture was not attempted, it seemed likely that these lesions represented remnants of previous A. suis or possibly A. lignieresi septicaemia.

Alimentary tract disorders

Signs of incoordination in four pigs and two deaths among ten-week-old pigs on a nursery unit prompted submission of one live affected pig. General poor growth was also reported in the group. The pig was in moderate body condition, appeared ataxic with a tendency to sternal recumbency and some fore and hind-limb proprioceptive deficits were noted. Rectal temperature was normal and there was evidence of a brown mucoid scour. Post mortem examination revealed an extensive typhlocolitis with histopathological lesions consistent with Brachyspira pilosicoli infection, although no Brachyspira spp. were isolated on culture. In the brain there was evidence of mild eosinophilic vasculitis and perivascular submeningeal oedema consistent with moderate water deprivation which is likely to have accounted for the neurological signs observed and possibly the deaths reported. Accumulations of urate crystals in the renal tubules suggested that the dehydration had been ongoing for several days and the typhlocolitis may well have exacerbated the situation.

Respiratory tract diseases

Four finishing pigs were submitted from a unit reporting an outbreak of widespread coughing with some "sudden deaths". Actinobacillus pleuropneumoniae (a serotype 3 which also cross-reacted with serotype 8) was isolated from characteristic lesions of acute pleuropneumonia in all four pigs. Although a viral trigger for the outbreak was suspected, no suggestive histopathological lesions were observed in any of the pigs examined.

Reproductive tract conditions

Five aborted foetuses were examined from a sow reported as "toxic" at time of farrowing two days before expected date. The foetuses were autolytic, consistent with death in utero at least 24 hours previously. Pure growths of E. coli were obtained from foetal stomach contents and placentae and histological examination of the lungs revealed bacterial colonies and associated inflammation. Bacteria were evident in the placentae but there was no evidence of inflammation. Serological testing of a pooled foetal fluid sample revealed a low positive titre (1/25) to L. interrogans serovar bratislava, indicative of in utero exposure to the organism but the significance of this to the case is not clear. No specific herd abortion or infertility problems were reported but serological testing of a proportion of sows to assess the extent of Leptospira infection was suggested.

Musculo skeletal conditions

Two three-month-old pigs from a straw-based finishing unit reporting acute onset stiffness/lameness were submitted for post-mortem examination following euthanasia. In addition to the lameness that appeared around three weeks after arrival on the unit, some pigs were described as apparently unwell. On gross examination, marked fibrinous arthritis with synovial hyperplasia was noted in the hock, shoulder and elbow joints of one pig and in one shoulder joint in the other pig. Histopathological examination revealed chronic hyperplastic synovitis with diffuse mononuclear cell infiltration, consistent with chronic mycoplasmal-type synovitis, although no Mycoplasma spp. were isolated on culture. In one of the pigs there was also evidence of a complicating bacterial-type synovitis. Treatment of cases with parenteral tylosin and penicillin was apparently successful.