As with hair, each feather normally emerges from one follicle. Polyfolliculosis (sometimes called pruritic polyfolliculosis or polyfolliculitis) is a malformation of the feather follicle in which multiple feathers (2-6) grow within one follicle. In fact, as many as 12 feathers have been reported within a single follicle. The word "pruritic" means "itchy".
What are the symptoms of polyfolliculosis?
In cases of polyfolliculosis, the feathers tend to be short and somewhat thickened. They often have retained feather sheaths. Although they can form anywhere, they tend to form around the neck, thigh, and tail (both the top and bottom). This condition seems to make the bird itchy and affected birds often become feather pickers with feather damage and balding in the affected areas. Bleeding or evidence of self-trauma may be present. The itchiness can be intense and prolonged.
Lovebirds and canaries are the most commonly affected species, but parakeets (budgerigars) and cockatiels can also be affected. Sometimes a tentative diagnosis is made based on the location and intensity of the itching, as the bird may have pulled out the evidence and no follicles are seen with multiple feathers in them.
What causes polyfolliculosis?
Polyfolliculosis is suspected to be caused by a virus but this has not been confirmed. A genetic defect may also play a factor in the development of this condition. Often only one bird in a collection is affected. Tests can be performed to exclude other problems such as Chlamydophila, intestinal protozoa, beak and feather disease, polyomavirus, liver disease, dermatitis, and lead poisoning. Blood tests, fecal tests, skin biopsies and DNA screening may be recommended to aid in the diagnosis of the aforementioned diseases.
What is the treatment for polyfolliculosis?
"There is no specific treatment for polyfolliculosis."
If blood tests or biopsies are negative, oral or topical medications may help manage the itchiness or calm the bird with reasonable success. Collars may be applied to manage cases where self-trauma is involved.
There is no specific treatment for polyfolliculosis. All treatments are considered "bandage" solutions, as they help manage the disease but they are not a cure and do not address the underlying cause.
Consult a veterinarian familiar with birds to discuss this challenging problem. The Association of Avian Veterinarians website, www.AAV.org, is a great place to find an avian veterinarian in your area.