The Treatment of Mycoses in Reptiles: a Review of Antifungal Drugs

With the advent of increasingly sophisticated diagnostic tools, mycoses in reptiles are nowadays often diagnosed ante-mortem and the clinician needs to decide on an optimal course of treatment. The disease process might be quite advanced by the time the animal exhibits clinical signs, as is typical of many non-traditional pet species, and therefore, delaying treatment or selecting inappropriate antimicrobials may easily cost the animal’s life. In most patients, stabilization by means of fluid therapy, and thermal and nutritional support is warranted prior to initiating further diagnostic procedures, or prior to instituting specific antifungal drug therapy. Radiographs, coelomic echography, MRI or other scanning device, complement a thorough physical examination and can all help to determine the extent of fungal disease by identifying visceral dissemination or the actual extent/depth of dermatomycotic lesions. A complete blood count is useful in assessing the quality of the patient’s immune response, and a serum chemistry panel may support a diagnosis of organ involvement as suspected by imaging findings, and will be used to compare with sequential serum chemistries after initiation of antifungal drugs, so that hepatoor nephrotoxicity can be identified early. Follow up imaging may also be useful to monitor treatment progress, and even determine duration of antifungal therapy. A thorough review of the husbandry is always indicated to identify and correct any perceived deficiency but in some mycoses, such as in infections with the Chrysosporium anamorph of Nannizziopsis vriesii (CANV), there may be no obvious or identifiable inadequacy in the captive husbandry. Mycoses in reptiles can be cutaneous (dermatomycoses) and/or systemic (pulmonary, renal, hepatic, disseminated, etc). Dermatomycoses in reptiles are practically never restricted to the epidermis. In reptile skin infections, dermal invasion is the rule. Since reptiles possess a very thin layer of connective tissue beneath the dermis (hypodermis), and the dermis often lies directly over subjacent muscles or bone, involvement of deeper tissues is very common when compared to mammals. The most common agent of dermatomycosis in reptiles, the CANV, readily invades the dermis and underlying structures. Therefore, the use of systemic drugs is not only practically always indicated, but is probably essential, as the use of topical antifungal compounds is unlikely to be successful, even with thorough debridement of infected skin and tissues, without the systemic use of an efficacious antifungal drug. Topical antifungal creams and ointments are an adjunct to systemically administered drugs. There exists a plethora of topical antifungal preparations, and to cover each is beyond the scope of this paper. In selecting a topical antifungal, the clinician might want to choose an antifungal that has a different mode of action as the one being administered systemically, so that 2004 Proceedings Association of Reptilian and Amphibian Veterinarians