Veterinary Services

Poultry and game birds

Increased mortality and poor egg production in terms of egg numbers and shell quality wereas reported in a multiage free-range flock. Many of the deaths appeared to be due to ante-mortem vent pecking and cannibalism, but birds that had been culled were found to be in moderate to poor condition, poorly feathered and with inactive ovaries and oviducts. The digestive tracts of some birds contained tangled vegetation and stones, and an underlying management/nutritional problem was suspected. Serology also showed recent exposure to one or more strains of infectious bronchitis virus.

Salmonella Pullorum was isolated from the oviducts of two layers aged 18 months, both of which had evidence of egg yolk peritonitis and impaction of the oviduct. There were no other fatalities in this small flock of 25 birds. Infection with S. Pullorum, known as pullorum disease or bacillary white diarrhoea, was at one time one of the most important diseases of young chicks in the UK, and incidents such as this serve as a reminder that the organism can still be found in some small "backyard" flocks.

Spironucleosis (hexamitosis) was diagnosed in adult red-legged partridges. The birds had been released the previous year and then caught again this spring for breeding purposes. Fifteen out of 100 birds died, and other birds were thin. Post mortem examination revealed watery intestinal contents containing large numbers of the motile protozoa Spironucleus (Hexamita) meleagridis. Infection with this organism is more often seen in young pheasants and partridges in rearing and release pens, but adult partridges also appear to be susceptible to this disease.

Wild and feral birds

Increased numbers of wild birds were submitted in March, largely for screening for avian influenza. Many of the birds had post mortem lesions consistent with trauma or starvation, but several infectious conditions were noted.

As reported elsewhere (Veterinary Record April 15th 2006, page 494), highly pathogenic avian influenza virus H5N1 was isolated from a whooper swan (Cygnus cygnus) found dead in Fife. The origins of this bird remain unclear, but genetic analysis indicated that the H5N1 virus isolated from the whooper swan was very similar to that isolated from swans from Germany and Poland, and from a buzzard (Buteo buteo) in Denmark.

Mycobacteriosis, presumed to be avian tuberculosis, was diagnosed in several birds submitted for avian influenza screening. Multiple lesions (Figure 1; click on PDF link on right) were found in a thin oystercatcher (Haematopus ostralegus) retrieved by a domestic cat. The liver was enlarged, with numerous miliary yellow foci, a large nodule was present in one lung, pale foci were noted in the spleen, and multiple nodules were attached to the serosa of the proventriculus, gizzard and intestine. An adherent pericarditis was present, and multiple nodules up to 1 cm in diameter were located between the skin and muscle of one thigh. Liver and lung lesions were also found in a thin greylag goose (Anser anser) but spleen and intestine appeared normal. An adult mute swan (Cygnus olor) had multiple caseous lesions in the liver, spleen, lungs and kidneys, but unlike the oystercatcher and greylag goose this bird was in good body condition. Mycobacteriosis, most likely avian tuberculosis, was also diagnosed in two feral ducks (a call duck and a Muscovy duck) from a pond in a public park. Similar to the mute swan, both birds were in good condition. Diffuse enlargement of the liver and spleen was present in both birds, the call duck also had a large caseous mass in one lung, and the Muscovy duck had numerous nodules in the spleen. In all the cases described here the diagnosis of mycobacteriosis was based on the demonstration of large numbers of acid/alcohol-fast bacilli on smears or histopathological examination of affected tissues. Histopathological examination of the enlarged livers and spleens of the call duck and Muscovy duck also revealed extensive amyloid deposits.

Other diagnoses of interest in wild birds included paramyxovirus 1 infection in feral pigeons (Columba livia), aspergillosis in several mute swans and a whooper swan, salmonellosis in garden birds, and a haemorrhagic tracheitis in a mute swan caused by the trematode Orchipedum tracheicola.