Treatment of cutaneous chytridiomycosis in blue-and-yellow poison dart frogs (Dendrobates tinctorius)

Donald K. Nichols and Elaine W. Lamirande

Department of Pathology, National Zoological Park, Smithsonian Institution, 3000 Connecticut Avenue NW, Washington, DC 20008 USA
Email: nichols@nzp.si.edu

We have used topical application of itraconazole (Sporanox, Janssen Pharmaceutica, Inc., Titusville, New Jersey, USA) to successfully treat cutaneous chytridiomycosis in blue-and-yellow poison dart frogs (Dendrobates tinctorius). In Experiment 1, juvenile frogs were experimentally exposed to Batrachochytrium dendrobatidis, a newly described fatal chytridiomycete (chytrid) fungus. Excessive shedding of skin was seen in all frogs 14 days post-exposure. Chytrids were present in the pieces of shed skin and in skin imprints made from the frogs. A 1% suspension of itraconazole was diluted to a final concentration of 0.01% itraconazole using 0.6% saline as the diluent. One group of frogs was immersed in this suspension for 5 min daily for 11 consecutive days. After the last treatment, the frogs were moved to clean cages and closely monitored. Another group of frogs served as positive controls and was not treated; they all died within 35 days of initial chytrid exposure. Clinical signs resolved completely in the itraconazole-treated frogs. These frogs were euthanized 63 days post exposure (38 days after the last treatment), and there was no histologic evidence of chytrid infection.

In Experiment 2, subadult and adult D. tinctorius were experimentally exposed to B. dendrobatidis and chytrid infections were proven through microscopic examination of skin imprints and pieces of shed skin. These frogs were treated with 0.01% itraconazole baths for 8 consecutive days and then moved to clean cages. Subsequent skin imprints from these frogs have been negative for chytrids and the frogs remain healthy 8 months later.