Canine flank alopecia: A narrative review of clinical presentation, genetic basis, and therapeutic management

Canine flank alopecia (CFA) is a seasonally recurrent skin disorder with a strong breed predisposition. Affected dogs display non-inflammatory, often hyperpigmented, well-circumscribed, symmetrical patches of hair loss, typically located on the thoracolumbar flanks. The onset of hair loss occurs during periods of decreasing daylight, usually in autumn or winter, with spontaneous partial or complete regrowth of hair during the following spring or summer. CFA is not associated with systemic symptoms and does not compromise the dog's general health. While the disorder is primarily considered a cosmetic condition, its chronic, cyclical nature and poorly understood pathogenesis present a challenge for veterinary clinicians and concerns for dog owners and breeders. This narrative review synthesizes current knowledge on CFA, discussing its clinical presentation, histopathological features, epidemiology, and suspected etiopathogenetic mechanisms, including photoperiod-dependent neuroendocrine influences and breed-related genetic predispositions. Diagnosis of CFA is based on signalment, the characteristic clinical presentation, exclusion of differential diagnoses, and supportive histopathology. Histological findings vary with disease stage and are suggestive, though not pathognomonic. Epidemiological data indicate breed predisposition and recurrence patterns, but quantitative data on prevalence are lacking. The pathogenesis appears multifactorial, likely involving interactions between environmental, neurohormonal, and genetic factors. Management of CFA ranges from watchful waiting to melatonin administration, with emerging treatments, such as low-level laser therapy, although evidence from placebo-controlled studies is limited. Current knowledge gaps on the genetic basis and biological pathomechanisms involved in CFA should be addressed through well-designed research, which will improve understanding and inform breeding strategies and management of CFA in veterinary practice.