Macroscopic, Histologic, and Ultrastructural Lesions Associated With Avian Keratin Disorder in Black-Capped Chickadees (Poecile atricapillus)

C. Van Hemert, A. G. Armién, J. E. Blake, C. M. Handel, T. M. O'Hara

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

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.

Original languageEnglish (US)
Pages (from-to)500-513
Number of pages14
JournalVeterinary pathology
Volume50
Issue number3
DOIs
StatePublished - May 2013

Keywords

  • avian keratin disorder
  • beak
  • black-capped chickadee
  • claw
  • deformity
  • hyperkeratosis
  • integument
  • wild birds

Fingerprint Dive into the research topics of 'Macroscopic, Histologic, and Ultrastructural Lesions Associated With Avian Keratin Disorder in Black-Capped Chickadees (Poecile atricapillus)'. Together they form a unique fingerprint.

  • Cite this