Adult‐onset hair loss in Chesapeake Bay retrievers: a clinical and histological study

Hair loss in Chesapeake Bay retrievers has been increasingly recognized by breeders in recent years. Anecdotal reports suggest an endocrine disorder or follicular dysplasia as the underlying cause, but no scientific study has been done to investigate the underlying problem. A prospective study was carried out in collaboration with the American Chesapeake Club. Affected dogs were recruited into the study. Routine dermatological and hormonal (blood and urine) tests, and skin biopsies were performed. Ten dogs (age 1.5–10 years), seven females (two spayed) and three males (two neutered), were included in the study. All dogs had mild or severe hair loss affecting the lateral ventral chest, flanks, rump and thighs. Affected dogs were clinically healthy. Hormonal tests revealed normal thyroid hormone panels, insulin-like growth factor-1 levels, and urinary cortisol:creatinine ratios in samples collected for ten consecutive days. In six of 10 dogs, an adrenal hormone panel showed slight or moderate increased values pre- and/or post-ACTH stimulation of cortisol (three of six), 17-hydroxyprogesterone (five of six), androstenedione (three of six), estradiol (two of six) and progesterone (six of six). The major histopathologic changes resembled canine flank alopecia and follicular dysplasia with pronounced infundibular hyperkeratosis, mild follicular atrophy, and occasional melanin clumping with dystrophic hair shafts. Chesapeake Bay retrievers suffer from a type of hair loss that is likely related to an abnormal production of adrenal sex hormone. Further studies are currently underway to determine if there is a heritable basis for this disease and to evaluate therapeutic options. Funding: University of Pennsylvania.