Lecture 15 Rosenthal

Cytology, Histology, and Microbiology of Feather Pulp and Follicles of Feather Pickers

Presenting Author: Karen L. Rosenthal, DVM, MS, Dipl ABVP (Avian), et. Al.

Department of Clinical Studies, University of Pennsylvania, PA

Interpretive Review and comments by Dr. Nemetz:

Dr. Rosenthal and her fellow authors tried to answer one of the more perplexing problems in feather picking/mutilating birds: Is the feather picking/mutilating site, where trauma is occurring, a site of inflammation within the skin or not?  If it is not or if the inflammation at the site of picking is not the same as in an unaffected site, then allergic dermatitis would be an unlikely diagnosis in cases of feather picking birds. Since allergies in birds have been discussed for years and often a diagnosis in feather picking, is it a correct diagnosis?

Dr. Garner's paper " Histological Description of Avian Noninfectious Skin Disorders" (Click here) classified the different types of skin pathology histologically from many years of submission to his pathology service. Dr. Rosenthal's clinical study involved an African grey parrot, sulfur-crested cockatoo, Moluccan cockatoo, scarlet macaw, harlequin macaw, Catalina macaw, yellow-nape Amazon, and a black palm cockatoo.

The results in this group of birds were compared to similar species that were not pickers and used as controls. None of the samples in affected or non-affected areas demonstrated any histological changes from normal. The authors concluded that if the skin is not pruritic, then the sole act of picking does not cause dermal damage.

Bacterial folliculitis is a common cause of pruritis in mammals and associated with allergic dermatitis and self-trauma. Because of this relationship, it has been assumed that birds "must" have the same etiology. This was not borne out in this study.


Often feather pickers are "diagnosed" as psychological in origin or as having an allergic dermatitis without a proper organized work-up to rule out systemic sources of pain or stress that may lead a bird to pick/mutilate. Also, many birds have been placed on various anti-inflammatories (antihistamines, steroids) in the hope it would solve the picking. Dr. Rosenthal as well as Dr. Nemetz has NOT seen these diagnoses or treatment programs result in any significant improvement in the bird's condition. However, only certain species were used in this study and generalized dermatitis has been shown in certain species of birds (Dr. Garner's paper) with or without concurrent feather picking. Dr. Bob Schmidt also commented that he has seen dermatitis in small passerines that when treated respond in their picking condition.

The take home message is: General inflammatory skin conditions do exist in psittacine birds, however their incidence is very low and may or may not play a direct role in the cause of a feather picking/mutilation condition. The test necessary to determine a true allergy is the comparative skin biopsy as mentioned by Dr. Garner.