Efficacy of a Silver-Based Shampoo for Treatment of Canine Malassezia: A Pilot Study.

Malassezia pachydermatis is a commensal of canines associated with Malassezia dermatitis. Consensus guidelines recommend topical and/or systemic treatment, but resistance to antifungals has been reported. The objective of this pilot study was to determine the efficacy of a 0.003% colloidal silver nanoparticle-based shampoo in the treatment of canine Malassezia dermatitis. Dogs were included based on compatible history, presentation, and at least one positive cytology. Fourteen privately owned dogs were bathed every 48 hr for up to 28 days, allowing 5-10 min of contact time. The mean Malassezia organisms for 10 oil immersion fields at each Malassezia dermatitis-affected body area was recorded at days 0 and 14. Dogs positive on day 14 had cytologies performed on day 28. Eleven dogs (78.6%) were cytologically negative by day 28. Nine (81.8%) of these were negative by day 14. One dog (7.14%) had partial resolution (negative in 3/4 Malassezia dermatitis areas) by day 28. These results suggest that silver nanoparticle-based shampoo may be effective in the treatment of canine Malassezia dermatitis. Larger, controlled studies are needed to further investigate efficacy, optimal concentration, and ideal application frequency.