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VLA: High Incidence of Rectal Stricture in Pig Herd

by 5m Editor
14 September 2010, at 8:03am

UK - A high incidence of rectal stricture in a large pig herd usually considered sporadic, made a significant contribution to the herd's overall mortality figures, according to the Veterinary Laboratories Agency (VLA) in its report for July 2010.

Reproductive diseases

Bury investigated a problem of increased regular returns associated with copious muddy cream-coloured vaginal discharges in returning sows. The farrowing rate, usually around 80 per cent, had dropped to 65 to 70 per cent. There was no increase in abortions, piglet viability was good, sows were healthy and rearing pigs were performing well. All the sera submitted tested positive for antibody to Leptospira Bratislava, some with titres of 1/200 and one at 1/400, suggestive of recent infection. It is uncertain whether Leptospira Bratislava infection plays a role in porcine reproductive disease, however given these findings, strategic medication was implemented on the unit while investigations continued into other possible causes. Although these sows are on an outdoor unit, the service area is indoors with a push through dunging passage and despite hygiene being visually good, cleaning and disinfection of the area was carried out.

Alimentary tract diseases

Rectal strictures

Thirsk carried out an investigation into an unacceptably high incidence of rectal strictures on a 4,000 pig, continuous flow, wean to finish indoor unit, where pigs were reared on a mixture of slatted and partially slatted accommodation. Post weaning mortality was estimated to be 7 per cent of which 2 per cent to 3 per cent was estimated to be solely due to rectal strictures. It was determined that animals became viraemic for PRRS in their first three to four weeks on this unit and this may have predisposed to septicaemia/bacteraemia and bacterial emboli settling out in the (non collateral) circulation to the terminal rectum. This may have resulted in ischemia and necrosis resulting in fibrosis as suggested by Wilcock and Olander in 1977 (Veterinary Pathology 4:36 – 42). Pigs presented clinically with a severely distended abdomen and rapid weight loss requiring euthanasia. The exact pathogenesis of rectal stricture is not fully elucidated although genetic susceptibility, lupin meal toxicosis, excess lysine in the diet, excessive coughing, and shortcoming in the environmental situation, have also been suggested as potentially contributory factors.

Respiratory Diseases

Lungworm


Fig. Metastrongylus spp in the airways of the caudal lobe of a 13-week-old pig

Approximately 50 per cent of a group of 240 13-week-old finishing pigs on a continuous outdoor unit were affected with coughing and wasting and mortality had increased in recent weeks. Several pigs were submitted to Bury for necropsy which revealed Metastrongylus species worms in the airways association with multifocal pulmonary consolidation, mainly affecting the ventral margins of lung lobes and caudal margins of caudal lung lobes. The worms were mainly visible in the caudal lung lobes (Figure). Salmonellosis was a consistent concurrent finding and may have contributed to the ill thrift and mortality. Additional findings in individual pigs were PCVAD, intestinal adenomatosis, Brachyspira pilosicoli and polyserositis.

Other diseases

Lymphosarcoma affecting lymph nodes, heart, bladder and spleen was diagnosed in a 15-month-old Gloucester Old Spot sow which had been seen ill in the two week period after farrowing. This was a sporadic case of lymphosarcoma, a relatively uncommon disease in pigs; however a familiar form has been described in Large Whites.

Further Reading

- Find out more information on the diseases mentioned by clicking here.

5m Editor