Papovavirus induced feather abnormalities and skin lesions in the budgerigar: clinical and pathological findings.

Feather abnormalities and skin lesions caused by a papovavirus infection in budgerigars are described. Diseased one to 15 day old birds displayed a lack of nestling down feathers and filoplumes on the head and neck. Survivors older than 15 days exhibited retarded growth and temporary absence of feathers variable from bird to bird. Several birds between 15 and 25 days of age had flight feathers with total absence or marked sparseness of the vanes. After 25 days, feathers began to grow, although the tail and/or some flight feathers of some of the birds remained underdeveloped or absent for several weeks. Several of these affected birds were unable to fly and are called "runners"Microscopic lesions in the feather follicles of the affected birds less than 15 days of age, were characterized by focal, multifocal or diffuse ballooning degeneration in the lateral and axial plate cells of the barb ridges with the presence of large basophilic or amphophilic intranuclear inclusions in the same cells. Focal areas of ballooning degeneration with intranuclear inclusions were also found in the epidermis. Clinical observations made on these birds are compared with those reported in the literature for French molt.