Abstract
The waldrapp ibis, also known as the Northern bald ibis, is a critically endangered bird with a small wild population existing in Morocco.1 Sixteen institutions in the United States that hold this species were surveyed in 2010 regarding health, veterinary care and nutrition and all institutions responded. Of those surveyed, 13/16 (81%) of institutions reported birds with skin lesions in their collections. The survey revealed that 42/132 captive U.S. birds (approximately 32%) suffer from some degree of chronic, ulcerative dermatitis that is minimally or non-responsive to medical intervention. This condition is often progressive and may become so severe that it results in the death of the bird, either by humane euthanasia due to lack of response to treatment, or by sequelae such as bacterial infection.
Skin lesions are usually located on the dorsum and may affect the entire back of the bird. Lesions may also be found in the axillary regions, and occasionally on the keel. Early in the disease process, lesions may appear as areas of feather loss, often accompanied by erythema and hyperkeratosis or flaky skin. As the lesions worsen, a thick scab may develop which cracks and bleeds. Lesions may wax and wane but often progress to an ulcerative, exudative dermatitis.
Histopathology of affected skin usually reveals chronic, hyperplastic, hyperkeratotic, ulcerative and crusting dermatitis. Bacterial or granulomatous folliculitis is often present, as is perivascular inflammation. Occasional smooth muscle mineralization has been seen, consistent with a chronic inflammatory process. The majority of biopsies collected have been from affected skin only. A more systematic approach to diagnostic workups is recommended, to include both affected and unaffected skin biopsies, as comparing the two can be helpful in determining the presence of true inflammatory disease.2
A myriad of treatments have been used to treat dermatitis in the waldrapp ibis including targeted antibiotics based on culture and sensitivity results, anti-inflammatory drugs, antifungals, psychotropic drugs, antihistamines, debridement and bandaging, vests and collars, and various nutritional supplements. Medications have been administered orally, parenterally, and topically. In some cases, clinicians felt that they were able to keep the lesions from progressing, but few felt that medical intervention helped to any meaningful extent. Sun exposure was cited by a few veterinarians as helpful in drying out the lesions, which can become very moist and exudative.
Enrichment was recommended by several institutions who felt that it decreased self-mutilation behaviors. Wild waldrapps spend several hours a day foraging with their long bills in sandy soil, under rocks, and in crevices for insects and other food items. Provision of a soft substrate for probing with the beak, and scattering live insects could decrease self-mutilation by increasing time spent foraging. One institution trained ibis to approach keepers for hand-fed treats and to step onto a scale, and reported decreased stress and increased play behaviors.³ Auditory enrichment has recently been successfully used to increase breeding behavior and reproductive success (Hofling, personal communication).
To date, no one etiology has been definitively identified and the problem is believed to be multifactorial in origin. Self-mutilation as a result of behavioral and social stress is currently thought to be the primary initiating factor for the development of dermatitis in this species (Hofling, personal communication). A highly social and gregarious species, the waldrapp ibis is currently recommended to be maintained in groups of more than 8–10 birds by both the European Endangered Species Program (EEP) and the AZA’s Species Survival Plan (SSP). Maintaining birds in smaller groups than this, or upsetting the social structure of the group by translocating mature birds can contribute to stress (Hofling, personal communication).
Further research is planned to determine if abnormal nutritional status might predispose this species to the development of ulcerative dermatitis. Collection and comparison of all biopsy histopathology are underway, and recommendations for systematic biopsy collection are planned.
Acknowledgments
The authors would like to thank Dr. Miguel Quevedo of Jerez Zoo in Spain, and Veterinary Advisor for the IAGNBI for sharing his many years of experience regarding dermatitis in the waldrapp ibis. The authors are also grateful to the institutions who responded to our survey, and whose contributions will increase our understanding of this significant disease process.
Literature Cited
1. Boehm, C., Bowden, C., Jordan M. 2003. Northern Bald Ibis Conservation and Reintroduction Workshop, Proceedings of the International Advisory Group for the Northern Bald Ibis (IAGNBI) Meeting Alpenzoo Innsbruck, Tirol, July 2003.
2. Garner, M.M. 2006. Techniques and trends in the characterization of inflammatory skin disease in feather picking birds. 2006 Proceedings of the American Association of Zoo Veterinarians, pp 19–21.
3. Mark, E. 2004. Reducing stress in northern bald ibis through training. Presented at AZA Workshop, Avian TAG Meeting, in Spring 2004. Available at www.reachingtheanimalmind.com.