Doyle's Dart Den



Brian Monk

The following was published in the ADG Newsletter No. 31 January - March 1997 and is used here with the permission of the ADG

A parasite, technically speaking, is any organism that lives on or within a host organism, and causes harm to that host while carrying on the basic functions of its own life.  Many types of parasites exist, from plants to fish.  However, the most common parasites are generally either protozoans from a few genera, or metazoans, usually "worms."  Most people think of parasites as being in the digestive tract, but they can inhabit any organ or tissue of the body.  Parasites exist in just about every species of organism on this planet.  Even parasites have parasites!  They are common and natural, but not always good.

Some parasites require more than one host to complete their life cycles.  They may use an insect as an intermediate host for part of their development, and as a way to be passed on to the primary host where they reproduce.  Tapeworms are a good example of a parasite that needs a secondary host.  Other parasites have a more succinct life-cycle, and are directly infective to the primary host, either as eggs or as immature organisms.  These types of parasites are represented by the hookworms and
roundworms, and many types of protozoal parasites.

Parasites are one of the most common afflictions of captive frogs, whether they are wild-caught or captive bred.  They can also be one of the most devastating.  All wild frogs have a parasite load ... that is, a population of various parasites.  These parasites in a normal, healthy, wild frog do not present a problem.  The frog is adapted to its parasite load.  In other words, the damage that these parasites create is compensated for by the frog.

A problem occurs when a wild frog is brought into captivity.  Try as we might, the captive environment is stressful, and frogs take time to establish themselves in their new homes.  Unfortunately, the parasite load has not diminished, and the added stress is sometimes enough to make a formerly healthy frog decompensate or "de-adapt" from this parasite load. A state of disease results, as the frog is no longer able to compensate for the damage done by the parasites. What we see as keepers is a normal healthy frog that for some reason becomes sluggish, lethargic, and starts to lose weight in spite of a good appetite.  Sometimes "worms"  are passed in the feces.  In some cases, the cloaca become prolapsed outside of the frogs body as a result of straining during defecation or irritation caused by the parasites.  It is important to note that many animals may already be displaying these symptoms by the time we have obtained them from the dealer.

Directly infective parasites can be devastating to captive populations of frogs.  As the parasites continue to produce offspring or eggs, these infectious stages build up in the enclosure and reinfect the frogs, producing a cycle that may result in a extremely high parasite load which the frogs cannot adapt to.  Good sanitation of the enclosed cage is highly recommended.

The most common parasites that a veterinarian sees are nematode worms of various types.  Hookworms, roundworms, and pinworms are probably the most commonly encountered parasites of frogs.  Other less common (but no less dangerous) parasites are flatworms (flukes), pentastomid worms (actually a type of arthropod), arrow-head worms, tapeworms, lungworms, and various protozoans (including amoebae).  For some of these parasites, detection and/or treatment is difficult.

In general, a veterinarian will check for parasites by making a suspension of feces and sugar solution, and then cover the vial with a slide so that it touches the suspension.  The parasite ova will float to the top, and can be checked for microscopically.  Direct smears of feces are also examined, particularly for protozoans.  Some parasites do not produce eggs that appear in the feces, and some parasites only shed eggs intermittently, so these tests are by no means absolutely correct all of the time.

In general, parasites should be dealt with before they become a real problem.  This means prophylactic treatment and/or quarantine!! Prophylactic treatment should consist of two doses of an anti-parasitic drug given one to two weeks apart. The most common broad-spectrum anti-parasitic compounds used by veterinarians in this country are fenbendazole (Panacur®) and ivermectin (Ivomec®).  Although these two drugs have a broad range of doses and a relatively safe, accurate dosing for small frogs is recommended and emphasized.  Transdermal administration is possible, but should fall within the ranges of safe dosages.   I cannot recommend to anyone the liberal application of a drug to a frog's back.

Quarantine means isolating the frogs from other frogs and their future environment for a set period of time.  This should be minimally thirty days, preferably in a situation where fecal samples can be monitored.  An easy way to do this is to house the frogs in a plastic storage container with a substrate such as moist paper towels.  Feces can easily be collected, and the towels can be changed often.  Prophylactic treatment should be done while the animals are in quarantine.

Established frogs that start to develop problems maintaining weight or appear "sick" should have at least one (preferably three) fecal exams run on fresh feces, to rule out GI parasites as a potential diagnosis.

In conclusion, parasites are a definite problem encountered by anyone who keeps frogs.  They are naturally occurring, and almost all wild-caught frogs have a parasite load.  The stress of captivity may cause frogs to "de-adapt" and the parasite load may lead to a sick frog.  Basic prophylaxis, quarantine, and sanitation are effective means of preventing parasite problems in both wild-caught and established frogs.

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