Veterinary Services

Poultry and game birds

Impaction of the crop with a tangled mass of long fibrous material was found in a free-range layer. Several birds in this particular paddock had lost weight and died or been culled. Further enquiries revealed that the grass in this paddock had become very long and had been cut, but the cut grass had not been removed.

Marek’s disease was diagnosed in a chicken from a small flock where several birds had developed paralysis. No abnormalities of the sciatic nerves were noted on gross post mortem examination but histopathology revealed focal and locally diffuse lymphocyte and plasma cell infiltration consistent with a diagnosis of Marek’s disease.

Aortic rupture was confirmed in a male turkey that had been found dead. The owner had reported five deaths in the group of 400 birds, all in excellent body condition and almost ready for slaughter.

Game Birds

Deaths due to a combination of coccidiosis and gapeworms were recorded in red-legged partridges that were still in release pens. Ten out of 60 birds had died in the past few days, but there had been no problems with previous batches and these birds were on a fresh site.

Diffuse pallor and substantial enlargement of the spleen was noted in a pheasant that had been shot and submitted to a processing plant. The liver was also slightly enlarged. Although the gross appearance was not typical of avian tuberculosis, Ziehl-Neelsen stained smears demonstrated many acid-fast bacilli typical of Mycobacterium avium. Histopathology of the spleen subsequently showed that much of the parenchyma had been replaced by pale eosinophilically-staining material presumed to be amyloid, with multifocal infiltrations of large epithelioid macrophages throughout the tissue. Light-to-moderate numbers of acid-fast organisms consistent with Mycobacterium species were visible in sections of both liver and spleen.

Pigeons

The owner of a recently established flock of 50 fantail pigeons submitted two of his birds for examination. Several pigeons had been lost over the previous few days and others appeared lethargic and anorexic. Both submitted birds were in poor body condition and had empty crops. The main postmortem finding in one bird was considerable enlargement of the liver, which appeared friable and showed diffuse pale degeneration throughout. The kidneys in this pigeon were similarly pale, enlarged and soft. The other submitted bird showed a fibrinous pericarditis and enlargement of the kidneys. A heavy growth of Salmonella Typhimurium phage type 2 was isolated on culture of tissues from both birds. Advice on the zoonotic risk of this infection was relayed to the owner of the pigeons, and the Divisional Veterinary Manager of the Animal Health Office was informed.