Veterinary Services

An organic unit in its first year of turkey production for the Christmas market reported ten deaths in a group of 50 birds aged three months. Affected birds appeared lethargic and unable to rise, adopting a “sitting position”. The long bones appeared “rubbery” and were easily incised with a scalpel blade. There were mid-shaft transverse fractures of the femurs. The gross findings and clinical history were  consistent with rickets. Supplementation with vitamin D and calcium was advised.    

Two adult cockerels were submitted from a multi-age free-range enterprise that regularly acquired new birds from multiple sources. Several birds had appeared disorientated and gone off their legs in the past 18 months. They gradually became weaker, lost weight and died. A moribund bird considered typical of the problem was submitted for necropsy. No significant gross lesions were noted.   The history  suggested the classical form of Marek’s disease but the peripheral nerves appeared normal. However histopathology demonstrated a multifocal non-suppurative encephalitis consistent with (but not pathognomic for) Marek’s disease. The second cockerel was in better condition and had multiple yellow coalescing irregular nodules four to five millimetres in diameter on the liver. Marek’s disease was again considered, but histopathology revealed multiple heterophilic granulomata surrounded by proliferating lymphocytes. A bacterial aetiology rather than Marek’s disease was indicated. The SAC considered that several different problems were responsible for the deaths that had occurred on this site.

Infection due to Mycobacterium avium infection was diagnosed in two aged laying hens submitted from a small free-range flock. Characteristic yellow- or cream-coloured nodules were seen in the liver, spleen and intestine. Large numbers of acid-fast bacilli were seen in smears of the lesions stained with Ziehl-Neelsen.

Two adult female silkies were received for necropsy. One had died suddenly and the other following a short period of dyspnoea. Postmortem examination showed that both birds had enlarged pale friable livers and large quantities of fat around the heart, lungs and viscera. A diagnosis of fatty liver syndrome was made, and advice offered with regard to feeding the remaining birds.

Game birds

Erysipelothrix rhusiopathiae was isolated from the viscera of two red-legged partridges aged 17 weeks. The birds had died in good body condition, with few postmortem features other than haemorrhages on the breast muscles. Erysipelothrix is a well-recognised cause of mortality of well-grown pheasants and partridges.

Captive birds

Change of voice and breathing difficulties were reported in a captive sparrowhawk before it died. At necropsy the syrinx was found to be partially obstructed by caseous material, from which Aspergillus fumigatus was isolated.

An adult female zebra finch was found dead with no prior signs of illness. No significant gross lesions were noted at postmortem examination, although an egg was seen in the oviduct. Histopathology subsequently demonstrated an acute focal serofibrinous pneumonia, with clusters of purplish basophilic material thought to be yolk droplets associated with the lesions. Similar material was seen within the major blood vessels of the heart. Egg yolk embolism and pneumonia have previously been described in birds presenting with severe respiratory distress.

Wild birds

Three of 17 birds found dead in a residential area of Glasgow were submitted to investigate the cause of the mortality. The birds were waxwings (Bombycilla garrulus). All three birds had died from trauma, probably following collisions with windows. There were several other reports of flocks of waxwings in the city.  Such irruptions into the UK can result from severe weather or food shortages in the birds’ normal wintering grounds in northern Europe. Trauma was also found to be the cause of death of other wild birds including a buzzard (Buteo buteo), red-breasted merganser (Mergus serrator), dunnock (Prunella modularis), barn owl (Tyto alba) and blackbird (Turdus merula). A thin merlin (Falco columbarius) had a greatly thickened oesophagus associated with many hairworms. Trichomonosis was considered to be the cause of oesophagitis and death of a greenfinch and siskin (Carduelis spinus) from two different locations.