What is psittacine beak and feather disease?
The arrow points to a diseased feather on the head of an umbrella cockatoo.
(Photo: Dr. Gregory Rich, DVM)Psittacine beak and feather disease (PBFD) was first described in Australian cockatoos in the early 1970s. Since then, the disease has infected over 50 different species of birds. PBFD attacks fast-growing epithelial (skin) cells, causing visibly abnormal formations of the beak and/or feather follicles.
In general, PBFD affects parrots that are native to Africa, Australia, New Zealand, and Indonesia. It is rare in neotropical parrots, such as macaws, amazon parrots, and conures.
PBFD is a member of the Circovirus family of viruses. Avian circoviruses affect not only parrots but also pigeons and chickens. This handout focuses on PBFD in members of the parrot family, also known as psittacines.
How do birds become infected with the virus?
When exposed to a bird that is positive for PBFD, susceptible birds can become infected through the oral cavity, nasal passages, or the cloaca (the common receptacle in which the urinary, gastrointestinal, and genital tracts empty). The virus is readily shed in the feces and the crop (storage area for food in the bird’s neck).
Viral particles shed into the crop may be passed from parents to offspring during feeding of crop milk. High concentrations of the virus are also shed in feather dander/dust from infected birds, which can adhere to a person’s clothing or hair and then be spread to more birds.
What are the clinical signs of psittacine beak and feather disease?
It may take weeks to years before infected birds show any clinical signs, depending on the bird’s age. Often, the first visible clinical sign is either severe beak deformation or necrotic (dead), misshapen, or abnormally formed feathers (feather dystrophy). Once symptoms are noted and the diagnosis is confirmed by laboratory analysis, most birds die from secondary infections within months to years.
Affected feathers may appear stunted, club-shaped, or pinched off. Beak malformations usually occur in white cockatoo species; the beak will appear elongated, excessively flaky or shiny, and will easily break with simple handling. PBFD infection may occur at any age but is most common in birds under three years of age.
There are several forms of the disease; the form that occurs in a given bird is influenced by the bird’s species and the bird’s age when it was infected.
- Peracute: The peracute form occurs in neonatal (recently hatched) birds. Clinical signs are generalized weakness and depression caused by septicemia (bacterial infiltration of the bloodstream), which is often accompanied by pneumonia, enteritis (infection of the small intestine), weight loss, and death. These young birds die before feather abnormalities are recognized, so the diagnosis is easily missed unless a necropsy (veterinary autopsy) and histology (microscopic examination of tissues) are performed on birds that die suddenly.
- Acute: The acute form develops in young birds that are infected as they develop their first feathers. The signs include depression for a couple of days followed by sudden changes in the formation and appearance of developing feathers, including premature molting. Some of these birds may die within two to four weeks.
- Chronic: The chronic form occurs in older birds. These birds progressively develop abnormal feathers in a symmetrical pattern that becomes apparent after each new molt. Short, clubbed feathers and deformed, curled feathers are seen. These changes occur in birds that have survived the acute stage of the disease. If affected birds live long enough, they may develop baldness. Beak deformities in juvenile and adult cockatoos may develop after substantial feather changes have occurred.
African gray parrots present with PBFD differently. These birds usually do not show feather or beak abnormalities. They show signs of generalized sickness, anemia (low red blood cell count), and/or have a very low white blood cell count, because the virus infects cells in the bird’s bone marrow, causing pancytopenia (a reduction in blood-forming cells).
How is the disease diagnosed?
To diagnose the disease, your veterinarian may take a skin and feather biopsy of sections of abnormal feather formation and send it to an avian pathologist to analyze for microscopic features of PBFD. A non-invasive way to diagnose the presence of the virus is to take a blood test or sterile swab of the oral cavity to obtain DNA of the circovirus.
How do I know if my bird is infected?
Birds can be screened for PBFD with a simple blood test. New birds should always be screened for the disease. A newly acquired young bird that is infected may not show clinical signs for a long time, and the owner should be aware of this. Many new birds are sold with a health warranty so if a bird tests positive, the buyer can return it if desired.
If you plan to purchase an additional bird, have both the resident bird(s) and new bird tested before they are exposed to each other. Birds that are symptomatic and test positive for PBFD via DNA probe are considered highly contagious to other psittacines.
How is psittacine beak and feather disease treated?
Unfortunately, there is no treatment for this usually fatal disease, though supportive care and a stress-free environment can extend the life of your bird. Your veterinarian can advise you on how to provide these for your bird.
- Keep infected birds isolated from non-infected birds, as the disease is easily transmitted to other parrot species.
- Do not let other people who also own birds visit or play with your PBFD-positive bird.
- Never take PBFD-positive birds to a boarding facility that houses other birds.
- Ensure your veterinarian is aware of your bird’s condition before any appointment.
