A double-blinded, randomized, controlled, crossover evaluation of a zinc methionine supplement as an adjunctive treatment for canine atopic dermatitis

Background - Zinc is important for skin health and proper immune system function. Hypothesis/Objectives - A zinc methionine, essential fatty acids (EFA) and biotin product (Zn supplement) was compared to an EFA and biotin product (control) in canine atopic dermatitis (CAD). Animals - Twenty seven client-owned dogs with chronic CAD receiving ciclosporin or glucocorticoids. Methods - A 24 week, randomized, double-blinded, controlled study with crossover at week 12 and 4 week period of allergy medication reduction at weeks 8 and 20. Evaluations included Canine Atopic Dermatitis Lesion Index (CADLI), pruritus Visual Analog Scale (VAS) and cytology sampling. Results - In dogs receiving the zinc supplement and ciclosporin for eight weeks, 44% (n = 7) had significantly decreased CADLI from 11.9 to 6.0 (P = 0.0002) with no significant change in pruritus VAS (P = 1.0). In dogs receiving the zinc supplement and glucocorticoids for eight weeks, 55% (n = 6) had significantly decreased CADLI from 10.9 to 5.0 (P = 0.0043) and pruritus VAS from 7.4 to 3.2 (P = 0.0166). For dogs receiving either steroids or ciclosporin there was a reduction in use of such medications, for at least four weeks, in 63% of dogs receiving the zinc supplement and 37% of dogs receiving the control. This difference was not significant (P = 0.1027). Seventy eight percent of dogs were diagnosed and treated for superficial skin infections during the study. Conclusions and clinical importance - This study supports a potential benefit of adjunctive zinc methionine supplementation in CAD. Dogs receiving glucocorticoids may be more likely to benefit. Further studies are needed to substantiate these initial results.