Canine Noninflammatory Alopecia: A Comprehensive Evaluation of Common and Distinguishing Histological Characteristics

The study investigated the histological features of skin biopsies from 76 dogs with various forms of noninflammatory alopecia, including alopecia X, recurrent flank alopecia, hyperestrogenism, hyperadrenocorticism, hypothyroidism, and primary alopecic disorders of unknown cause, compared to 38 control dogs. The results showed a significant increase in kenogen follicles across all hair cycle disorders, suggesting an impaired induction of the anagen phase. Specifically, dogs with alopecia X had the lowest percentage of anagen follicles and the highest percentage of telogen follicles. The study concluded that there is an impairment in anagen phase induction in these disorders and that premature catagen may contribute to their pathogenesis. The study highlighted the need for further research into the stem cell compartment and initiating factors for different cycle phases to fully understand the pathogenesis of canine alopecia.