Hypersensitivity and Intradermal Allergy Testing in Psittacines

Pathologic feather picking in companion avian species has been attributed to multiple underlying disorders, and many of these birds are thought to be pruritic. Allergies have been discussed as possible contributors to this common and devastating dermatologic disease. This article reviews published information and research currently being conducted on hypersensitivity disorders in avian species. Allergic dermatitis is given special emphasis, with a focus on diagnostic techniques, such as intradermal allergy testing and histopathologic findings in feather-picking birds. Avian dermatology is an important segment of companion bird practice, with feather picking being by far one of the most common, but also most challenging, dermatologic disorders in psittacine pet birds. Pathologic feather picking occurs when a bird damages its feathers or traumatically removes them from areas on the body that are accessible to its beak (Figure 1). In severe cases, the underlying skin can be considerably damaged, even to the point of fatal hemorrhage. Feather picking is not a specific disease but is rather the result of an underlying disease process or psychologic disorder. The most common causes of self-mutilation include nutritional deficiencies, toxins, infections, internal organ pathology, and psychologic factors. However, identification of an underlying disease often proves difficult, and many cases remain undi-