title: Canine noninflammatory alopecia: a comprehensive evaluation of common and distinguishing histological characteristics.
abstract: BACKGROUND
  Noninflammatory alopecia is a frequent problem in dogs, and the pathogenesis is still unclear.
  
  
  OBJECTIVE
  The objective of this study was a comparative histological description of skin biopsies from dogs with different alopecic disorders and control dogs matched for coat type, season and disease duration.
  
  
  METHODS
  Twenty-one cases of alopecia X in plush-coated dogs, 12 cases of recurrent flank alopecia, three cases of hyperestrogenism, 15 cases of hyperadrenocorticism, 12 cases of hypothyroidism and 12 cases of primary alopecic disorders of unknown cause were evaluated. The controls were biopsies from 38 dogs of different coat types.
  
  
  METHODS
  We evaluated five serial sections of each biopsy histologically and immunohistologically to compare the histological findings within the disease groups and with the control.
  
  
  RESULTS
  All the dogs with hair cycle disorders had a significant increase in the number of hairless hair follicles, which we assigned to kenogen. In addition, dogs with alopecia X had the lowest percentage of anagen follicles and the highest percentage of telogen follicles.
  
  
  CONCLUSIONS
  The marked increase in kenogen follicles is a strong indication that the induction of the new anagen phase is impaired in hair cycle disorders. The findings in dogs with alopecia X further suggest that premature catagen is also involved in the pathogenesis. Further work to investigate the stem cell compartment and possible initiating factors for the different cycle phases is required to elucidate the exact pathogenesis.
authors.affiliation: Institute of Animal Pathology, Vetsuisse Faculty, University of Bern, Länggassstrasse 122, CH-3012 Bern, Switzerland.
authors.forename: Tabitha
authors.initials: T
authors.lastname: Müntener
authors.forename: Gertraud
authors.initials: G
authors.lastname: Schuepbach-Regula
authors.forename: Linda
authors.initials: L
authors.lastname: Frank
authors.forename: Silvia
authors.initials: S
authors.lastname: Rüfenacht
authors.forename: Monika M
authors.initials: MM
authors.lastname: Welle
mesh_terms: D000505:Alopecia / Q000473:pathology / Q000662:veterinary*; D000818:Animals; D001706:Biopsy / Q000662:veterinary; D016022:Case-Control Studies; D004283:Dog Diseases / Q000473:pathology*; D004285:Dogs; D005260:Female; D006197:Hair / Q000473:pathology; D018859:Hair Follicle / Q000473:pathology; D008297:Male; D012867:Skin / Q000473:pathology; D013045:Species Specificity