PILOT STUDY OF INTRACOELOMIC TERBINAFINE IMPLANTS IN GREATER SIRENS (SIREN LACERTINA).

ABSTRACT

Chytridiomycosis caused by Batrachochytrium dendrobatidis (Bd) has been documented in greater sirens (Siren lacertina) in the wild and in the pet trade. This study evaluated the use of terbinafine-impregnated implants for chytridiomycosis prophylaxis in greater sirens exposed to Bd. Implants were placed intracoelomically in both control (blank implant, n = 4) and treatment (24.5 mg of terbinafine implant, n = 4) groups. Sirens were exposed to Bd zoospores via 24-h immersion bath at 1 and 2 mon postimplant placement. Blood was collected monthly for plasma terbinafine levels, and skin swabs were collected weekly for Bd quantitative PCR. Animals with terbinafine implants had detectable concentrations of plasma terbinafine ranging from 17 to 102 ng/ml. Only one terbinafine-implanted animal had a peak concentration above the published minimum inhibitory concentration for terbinafine against Bd zoospores (63 ng/ml); however, it is unknown how plasma terbinafine concentrations relate to concentrations in the skin. There was no difference between the two treatment groups in clinical signs or Bd clearance rate, and no adverse effects from implants were observed. These findings indicate using intracoelomic drug implants for drug delivery in amphibians is safe; however, terbinafine efficacy in preventing Bd chytridiomycosis in sirens remains unclear. Further investigation of the use of intracoelomic implants and identification of effective drugs and doses in other amphibian species against Bd and other infectious diseases is warranted, as this may provide a practical method for long-term drug delivery in wildlife.