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VLA: Fowl Cholera in Free-Range, Backyard Flocks

by 5m Editor
28 October 2010, at 9:09am

UK - Fowl cholera has been reported in commercial and backyard flocks in the Veterinary Laboratories Agency (VLA) Monthly Scanning Surveillance Report for September 2010.

Commercial Layers and Layer Breeders

Avian intestinal spirochaetosis

Avian intestinal spirochaetosis was diagnosed in a flock of 7000, 31 week-old free-range layers which were experiencing a drop in egg production. Post mortem examination of culled birds revealed regressed ovaries and distended caeca with pale frothy and yellow contents from which Brachyspira intermedia was isolated. Spirochaetosis in layers is often a problem of young flocks in the early part of lay, where it can be associated with drops in egg production failure to reach peak of production and failure to gain bodyweight.

Fowl cholera

Starcross investigated a 7,000-bird house of 64-week-old free-range laying hens which had suffered increased mortality since placement at 16 weeks. Total losses had reached nearly 15 per cent. A sudden worsening of the mortality triggered the submission of six birds for examination. Three of the birds had multiple 2-3mm foci throughout the liver and five had varying degrees of peritonitis. Pasteurella multocida was isolated in pure growth from four of the birds confirming fowl cholera.

Broilers and Broiler Breeders

Suspected transmissible viral proventriculitis

Proventricular lesions and histological correlates similar to those described in cases of so-called 'transmissible viral proventriculitis' were seen in 35-day-old broilers from two different houses from the same farm submitted with a history of poor growth. The main finding at post mortem examination was thickening of the proventricular wall. Histological examination of proventriculus revealed a multifocal lymphocytic proventriculitis with glandular degeneration and ductular hypertrophy and hyperplasia. Work in the United States has described a novel birnavirus in association with the condition which is antigenically and genetically distinct from the birnavirus causing infectious bursal disease (Gumboro disease). However, it is not known if a similar cause is implicated in the UK cases.

Backyard Flocks

Infectious Laryngotracheitis (ILT)

ILT was diagnosed as the cause of respiratory signs and increased mortality in immature birds in a flock of 200 chickens. Nine birds had died over a period of two to three weeks. Approximately two months earlier, a number of immature birds had been taken to a poultry market but returned to the flock because they were not sold. The main observation at post mortem examination was the presence of a severe laryngotracheitis in one of the birds, characterised by the presence of diphtheritic inflammation involving the proximal trachea and larynx.

Fowl cholera

Fowl cholera was diagnosed in chickens with respiratory disease at VLA Carmarthen. All had been displaying clinical symptoms including coughing, sneezing, nasal discharge, swelling of the eyelids and face. Birds were a mixture of ages and breeds from a number of sources. All five birds submitted were suffering from sinusitis and Pasteurella multocida was isolated from the sinuses of two birds.

Gamebirds

Spironucleus

Bury diagnosed Spironucleus infection as the cause of malaise and deaths in 12- to 16-week-old pheasants in release pens. The birds were in poor bodily condition with evidence of dehydration and caeca were distended with loose paste-like contents on post mortem examination. Moderate numbers of Spironucleus species (Hexamita species) were detected in the small intestine.

The disease was also described as the cause of losses in Red Partridge. In one case investigated, 100 birds died from a group of 8,500. Mixed motile protozoal infestations of Spironucleus species (Hexamita species) and trichomonads were detected by direct microscopy in the intestines.

Gapeworm and Capillaria

Approximately seven partridges were found dead every morning for three days out of a group of 1,500 13-week-old birds. The majority of the group also appeared weak and did not attempt to take flight. Necropsy of a dead partridge at RVC revealed a large number of gape worms in the trachea. In two other birds examined, there was no gapeworm infection, however, large numbers of Capillaria spp (hair worms) were visible in the upper alimentary tracts of these birds. There were also signs of dehydration with prominent ureters filled with urates and slightly dry caecal contents. Anthelmintic treatment was recommended.

Further Reading

- You can view the full report by clicking here.


Further Reading

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