The Merck Veterinary Manual, 9 edition
Pg 1467
Psittacine Beak and Feather Disease
Psittacine beak and feather disease (PBFD) is caused by a psittacine circovirus. The name is not representative of the typical clinical presentation, which does not include beak abnormalities and is less likely to have severe, classic feather abnormalities that were seen in cockatoos when the disease was first documented. PCR screening has greatly decreased the prevalence of the virus in 'Cacatua' ssp. Disease is still noted, however, in African Gray parrots, 'Eclectus', lovebirds ('Agapornis'), lorikeets, and other species. This debilitating infection may affect any psittacine, although Old World species are most suseptible, and has been reported in wild and domestic birds. The natural infection appears to occur primarily in juvenile birds, with a instances of clinical infection seen in birds >3 yr old.
Typical findings include feather loss, abnormal pin feathers (constricted, clubbed, or stunted), abnormal mature feathers (blood in the shafts), and a lack of powder down in applicable species. Pigment loss may occur in colored feathers. Immunosuppression is present. Acute infections in chicks also occur, with several days of depression followed by profound changes in the developing feathers and sudden death.
Diagnosis is based on gross appearance, PCR, and biopsies of affected feather follicles showing basophilic intracytoplasmic inclusions. PCR may be able to detect infection in birds that still appear healthy.
The contagious nature of PBFD and its probable terminal outcome in clinically affected birds warrent isolation and eventual euthanasia in most cases. Strict hygiene with attention to dust control, screening protocols including PCR, and lengthy quarantines are highly recommended in cockatoo breeding colonies. The removal of all eggs for cleaning and incubation may also be helpful.
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