ABSTRACT
A common clinical occurrence in dogs is otitis externa caused by excessive growth of yeasts Malassezia pachydermatis, which can become chronic after wrong treatments, in which microbial resistance can occur. Homeopathic remedies can be considered a successful alternative, selecting the medicine through the similitude principle. Herein, 50 µL of a 1:1000 dilution of Malassezia pachydermatis suspension at 0.5 McFarland scale was used to seed the yeast into Sabouraud dextrose agar plates using a Drigalski spreader to proceed with colony unit counting. Before being seeded, the yeast suspensions were treated with 1% of different homeopathic treatments previously selected from a pilot study, which means Sulphur 6cH, Dolichos pruriens 6cH, and Kali carbonicum 6cH, being water, and succussed water used as controls. For comparison, a set of Sabouraud dextrose agar plates containing 1% Tween 80 was seeded in parallel. The treatments were made blind and evaluated in triplicate. Contaminated cultures were withdrawn. The number of colonies per plate was assessed, and smears were made from the cultures to classify yeast growth according to cytomorphology on ImageJ®software. The preliminary results show no significant effect of all tested medicines compared to the controls. High data variability was also observed, mainly in those cultures whose medium was prepared with Twin 80. In conclusion, at this point of the study, no evidence of the effects of the studied medicines on Malassezia pachydermatis growth in vitro could be identified. The analysis of cytomorphology is still in course.