{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,26]],"date-time":"2026-09-26T01:42:56Z","timestamp":1790386976578,"version":"4.1.0"},"reference-count":36,"publisher":"SAGE Publications","issue":"3","license":[{"start":{"date-parts":[[2013,2,11]],"date-time":"2013-02-11T00:00:00Z","timestamp":1360540800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Vet Pathol"],"published-print":{"date-parts":[[2013,5]]},"abstract":"<jats:p>An epizootic of beak abnormalities (avian keratin disorder) was recently detected among wild birds in Alaska. Here we describe the gross, histologic, and ultrastructural features of the disease in 30 affected adult black-capped chickadees ( Poecile atricapillus). Grossly, there was elongation of the rhamphotheca, with varying degrees of lateral deviation, crossing, and gapping between the upper and lower beak. Not uncommonly, the claws were overgrown, and there was alopecia, scaling, and crusting of the skin. The most prominent histopathologic features in the beak included epidermal hyperplasia, hyperkeratosis, and core-like intrusions of necrotic debris. In affected birds, particularly those with moderate to severe beak overgrowth, there was remodeling of premaxillary and mandibular bones and various dermal lesions. Lesions analogous to those found in beaks were present in affected claws, indicating that this disorder may target both of these similar tissues. Mild to moderate hyperkeratosis occurred in other keratinized tissues, including skin, feather follicles, and, occasionally, sinus epithelium, but typically only in the presence of microbes. We did not find consistent evidence of a bacterial, fungal, or viral etiology for the beak lesions. The changes observed in affected birds did not correspond with any known avian diseases, suggesting a potentially novel hyperkeratotic disorder in wild birds.<\/jats:p>","DOI":"10.1177\/0300985812469637","type":"journal-article","created":{"date-parts":[[2013,2,11]],"date-time":"2013-02-11T22:25:56Z","timestamp":1360621556000},"page":"500-513","update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":20,"title":["Macroscopic, Histologic, and Ultrastructural Lesions Associated With Avian Keratin Disorder in Black-Capped Chickadees (\n                    <i>Poecile atricapillus<\/i>\n                    )"],"prefix":"10.1177","volume":"50","author":[{"given":"C.","family":"Van Hemert","sequence":"first","affiliation":[{"name":"United States Geological Survey, Alaska Science Center, Anchorage, AK, USA"},{"name":"Department of Biology and Wildlife, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"A. G.","family":"Armi\u00e9n","sequence":"additional","affiliation":[{"name":"Department of Veterinary Population Medicine, VDL, College of Veterinary Medicine, University of Minnesota, St Paul, MN, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"J. E.","family":"Blake","sequence":"additional","affiliation":[{"name":"UAF Animal Resources Center, University of Alaska, Fairbanks, AK, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"C. M.","family":"Handel","sequence":"additional","affiliation":[{"name":"United States Geological Survey, Alaska Science Center, Anchorage, AK, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"T. M.","family":"O\u2019Hara","sequence":"additional","affiliation":[{"name":"Department of Biology and Wildlife, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2013,2,11]]},"reference":[{"key":"bibr1-0300985812469637","doi-asserted-by":"publisher","DOI":"10.1111\/j.1748-5827.1965.tb04320.x"},{"key":"bibr2-0300985812469637","first-page":"742","volume":"97","author":"Brush AH","year":"1980","journal-title":"Auk"},{"key":"bibr3-0300985812469637","first-page":"607","volume-title":"Avian Medicine: Principles and Application","author":"Cooper JE","year":"1994"},{"key":"bibr4-0300985812469637","doi-asserted-by":"publisher","DOI":"10.1371\/journal.pone.0025877"},{"key":"bibr5-0300985812469637","volume-title":"Avian Histopathology","author":"Fletcher OJ","year":"2008","edition":"3"},{"key":"bibr6-0300985812469637","doi-asserted-by":"publisher","DOI":"10.1071\/BI9760467"},{"key":"bibr7-0300985812469637","doi-asserted-by":"publisher","DOI":"10.1080\/15287399109531538"},{"key":"bibr8-0300985812469637","doi-asserted-by":"publisher","DOI":"10.1525\/auk.2010.10111"},{"key":"bibr9-0300985812469637","unstructured":"Handel CM, Pajot LM, Matsuoka SM, et al. Potential Role of Environmental Contaminants in the Pathology of Beak Deformities Among Black-Capped Chickadees in South-Central Alaska. Final report. Anchorage: USGS Alaska Science Center; 2006. http:\/\/alaska.usgs.gov\/science\/biology\/landbirds\/beak_deformity\/pdfs\/Handel_et_al_2006_final_report_sm.pdf. 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