The efficacy of subcutaneous slow‐release melatonin implants in the prevention of canine flank alopecia recurrence is uncertain: A double‐blind, randomized, placebo‐controlled study

• Published in: Veterinary dermatology 2022-12, Vol.33 (6), p.553-558
• Main Authors: Verschuuren, Millie U. M. Y., Schlotter, Yvette M., Geijlswijk, Inge M., Lugt, Jaco J., Gehring, Ronette
• Format: Article
• Language: English
• Subjects: Alopecia; Alopecia - veterinary; Animals; Baldness; Biopsy; Dog Diseases - drug therapy; Dog Diseases - pathology; Dog Diseases - prevention & control; Dogs; Double-Blind Method; Double-blind studies; Injection; Lidocaine; Melatonin; Melatonin - therapeutic use; Original; Placebos; Skin - pathology; Statistical analysis; Transplants & implants
• ISSN: 0959-4493; 1365-3164
• DOI: 10.1111/vde.13122

Background Canine flank alopecia (CFA) is characterized by seasonally recurring noninflammatory, occasionally hyperpigmented alopecia predominantly in the thoracolumbar area. Previous studies suggest that reduced production of endogenous melatonin may play a role in the pathogenesis of this condition, and placebo‐controlled studies on the efficacy of preventative melatonin treatment are lacking. Objective To evaluate the efficacy of subcutaneous slow‐release melatonin implants in the prevention of CFA recurrence. Animals Twenty‐one client‐owned dogs with a history of CFA were included in the study. Materials and Methods At time (T)0, a general physical and dermatological examination was performed on each dog, blood was collected for serum biochemistry analysis and two skin biopsies were taken from alopecic areas on the nonsedated affected dogs after subcutaneous injection with 2% lidocaine. Dogs with normal blood work and histological results compatible with CFA were included in the study. Participating dogs were randomly assigned to receive either placebo or 18 mg melatonin subcutaneously in the interscapular area, approximately 2 months before expected CFA onset (T1). CFA recurrence was scored qualitatively as complete, ≤50% recurrence, or no recurrence at 5 and 7 months after the intervention (T2 and T3, respectively). Results At T3, in dogs treated with placebo (nine of 17), the percentages for complete recurrence, ≤50% recurrence and no recurrence were 44%, 0% and 56%, respectively. In dogs treated with melatonin (eight of 17), these percentages were 25%, 50% and 25%, respectively. There were no statistically significant differences in the scores between melatonin‐treated dogs and placebo‐treated dogs (p = 0.40). In three of eight melatonin‐treated dogs, mild transient swelling was observed at the injection site. Conclusions This study did not provide evidence that an 18 mg melatonin implant treatment, although well‐tolerated, is efficacious in preventing recurrence of CFA in affected dogs. Résumé Contexte L'alopécie récidivante des flancs du chien (AFC) est caractérisée par une alopécie non inflammatoire récurrente de façon saisonnière, parfois hyperpigmentée, principalement dans la région thoraco‐lombaire. De précédentes études suggèrent qu'une production réduite de mélatonine endogène peut jouer un rôle dans la pathogénie de cette affection, et des études contrôlées par placebo sur l'efficacité du traitement préventif à la mélatonine font défaut. O