The most common parasites of concern in amphibians are Rhabditiform nematodes (Rhabdias lungworms) and Strongyloides. These parasites can reach levels known as super-infections, which often result in in physiologic stress or even death. Screening and treatment of parasites will depend on a number of factors. A trained individual should always perform a fecal on all individual frogs entering quarantine. Risk analysis can be performed to determine whether a fecal is deemed necessary. If a frog or group of frogs is acquired from a reliable captive bred source, and have had no issues maintaining or gaining weight throughout quarantine, a fecal may not be necessary. All wild caught frogs should ideally have a fecal test performed prior to entering a permanent enclosure.
The elimination of all internal parasites is frequently impossible or undesirable. Rhabditiform nematodes are notoriously difficult to eliminate completely. Instead, the goal of treatment should be reduction of parasite loads through treatment and proper enclosure hygiene. It is especially important to keep in mind that for amphibians within survival insurance colonies, a low parasite burden of endemic parasites can be beneficial. This allows individuals to maintain a degree of natural resistance upon reintroduction into the wild.
Fecal evaluation should be performed within the first week of quarantine and a week prior to expected quarantine release. A use of a qualitative scoring system for numbers of parasite eggs can be helpful in determining if parasite numbers have been reduced after treatment. Treatment should be tailored on fecal evaluation and directed towards parasites that are known to cause deleterious effects to the host.
Rhabditiform nematodes have a direct life cycle which can occur in as little as 48 hours. For this reason, the treatment of rhabditiform nematodes is geared toward environmental hygiene, to control the free living environmental stages of the parasite, as well as administration of anthelmintics to reduce fecal parasite loads. For those individuals with high parasite burdens, housing in easily cleaned temporary enclosures with little organic material is ideal. This will allow for proper cleaning and removal of any eggs or larvae. During treatment, feces should be removed daily and substrate should be removed every two days. In addition, the entire enclosure should be rinsed out and disinfected every two days. A good substrate choice is a lightly moistened paper towel.
With administration of anthelmintic medications, knowing an accurate body weight will help with more accurate treatment. In addition, prior to treatment of a new species, only a few individuals within the group should be treated in order to determine whether this medication is safe to administer. All of the medications listed below have been used in a number of species, however toxicities can occur in new species. Accurate weights and careful attention to dosages and dilutions are fundamental to decreasing the risk of toxicity.
Sources Cited: Pessier, A.P. and J.R. Mendelson III (eds.). 2017.
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