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Amphibian Diseases: Bacterial And Viral Infections

When seeking treatment, veterinarians specialized in treating reptiles have the general background to effectively treat amphibians if they have the relevant references handy.

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Viral Infections

The diagnosis and treatment of viral infections in amphibians is outside of the scope of the hobbyist. Nonetheless, amphibian hobbyists should be aware of the risks of transmitting viral disease and the importance of quarantine to help prevent the spread of viral diseases.

Bacterial Infections

Identifying bacteria as a cause of disease in amphibians is difficult without the help of a qualified veterinarian. Because of the costs involved, most hobbyists keeping just a few amphibians treat sick frogs and salamanders with a broad-spectrum antibiotic and hope it works. Generally, bacteria is the cause of illness in your frog or salamander if the signs of decline are sudden, rather than gradual. These signs include inactivity, failure to feed, weight loss, cloudy eyes (if one has eliminated toxing-out syndrome), edema, and skin hemorrhaging. If these signs are noted, a first step is to reduce the risk of spreading a bacterial infection by transferring sick amphibians to a separate treatment container, such as a plastic terrarium.


Over-the-counter fish antibiotics, though readily available, are not always effective at treating amphibians when administered in water. With aquatic amphibians, sulfa-based fish medications have been used with varying degrees of success because they are readily absorbed through the skin. Other over-the-counter fish antibiotics used in baths are not very effective or have to be dosed at such a high level that they can cause other problems. For example, the proper concentration of tetracycline in a bath solution will damage the skin of amphibians. The route of administration also affects the speed of action. Many antibiotics act quickly if injected, while others are nearly as effective if administered orally.

One of the better-known bacterial diseases of frogs is called red-leg disease because of the subcutaneous hemorrhaging associated with the later stages of the disease. Red-leg disease is caused by bacteria of the genus Aeromonas. It can be treated with tetracycline at 50 mg per kg administered orally twice a day. Factors contributing to the onset of this disease, such as environmental stress from poor- quality water or exceedingly low temperatures, must be rectified. A general antibiotic that has proven effective for treating a variety of bacterial infections in amphibians is trimethoprim-sulfa, a prescription drug that is obtainable through your veterinarian. It is most effective if administered orally, but it can also be absorbed through the skin— either applied with a cotton swab or dissolved in a shallow level of water, such as a bath. Enrofloxacin (Baytril), an injectable and oral antibiotic that has proven effective against a range of bacterial infections, works at 5 mg per kg daily for seven days. Certain drug combinations that target both aerobic and anaerobic bacteria can also be very effective, such as metronidazole.

From a practical standpoint, communication with experienced amphibian keepers will often be the most effective method for deciding on treatment for bacterial infections. When seeking treatment, veterinarians specialized in treating reptiles have the general background to effectively treat amphibians if they have the relevant references handy.