Keeping Captive Amphibians Healthy
The prevention and treatment of disease in captive reptiles and amphibians has advanced greatly in recent years. Unfortunately, however, there is still a great deal that baffles us — our knowledge of amphibian medicine in particular is quite poor. On the positive side, we do know a quite a bit about the diagnosis and treatment of disease in tropical fishes, and much of the basic research behind this is applicable to amphibians.
Among the most important steps you can take to insure the health of your pet amphibians is to establish a relationship with a qualified veterinarian. Veterinary practices specializing in amphibian medicine, although by no means common, are on the increase. Your local herpetological society should be able to provide some leads.
Many medications designed for use with aquarium fish work well on related conditions in amphibians. Bare in mind, however, that amphibians absorb medication over a much greater area surface area that do fish — in many cases, the entire skin of the amphibian will allow transfer of the medicine. Although I have had success using certain medications in the same dosages as are recommended for fish, I always begin treatment with a 50% dilution and watch carefully for signs of stress (gasping, swimming about wildly, scratching, skin sloughing).
Good hygiene is the basic starting point for avoiding sickness, and, in some cases, even for treatment. Again, the porous nature of amphibian skin is a consideration – ammonia from waste products and other toxins in the terrarium will be absorbed through the skin if not removed.
Bottled spring water (not distilled water) should always be on hand. Salamanders and frogs suffering from ammonia or other chemical toxicity can sometimes be revived by placing them in such water and allowing it to flush harmful chemicals from the body.
Considering how little we know concerning the treatment of disease, prevention is vital. Always be sure to keep your pets in a secure, stress-free environment and provide each species with the appropriate temperature, humidity, light cycle and diet.
Handling Your Pets
Amphibian skin is extremely delicate, and its mucous covering repels attacks by harmful microorganisms. Extreme care must be taken in administering injections and in handling frogs and salamanders. Amphibians should be held with wet hands only, or confined within a water-filled plastic bag when being examined. Catching a frog or salamander with a stiff nylon net may also remove some of the skin’s mucous coating and expose the animal to bacterial infection. When in doubt, use a preparation designed to replace the mucus coating of aquarium fish.
Due to the nature of reptile and amphibian circulatory systems, injections of most medications are given in the front legs. If multiple injections are needed, a different leg, and a different site on each leg, should be used. This will go a long way in avoiding damage to the delicate skin.
The details of all the medical treatments administered to your pets should be recorded. Not only will this prevent mistakes, especially when you’re experimenting with different dosage levels, but a record of what you have done will also be very useful to yourself and others in the future, and may even lead to a new discovery.
A variety of Salmonella species are commonly present in amphibian digestive tracts. Many are easily transmitted to humans and can cause severe health problems, especially among the young, elderly and immune-compromised. It is essential that you discuss with your family doctor the best methods of avoiding the transference of Salmonella.
Otherwise healthy amphibians may harbor Salmonella without external symptoms. Animals suffering from an infection will usually cease feeding and become lethargic. Your veterinarian can diagnose Salmonella via blood tests (often the animal will be anemic) and fecal samples. Gentamicin and other antibiotics, methylene blue and acriflavine have proven useful against Salmonella.
This gram-negative bacterium causes many of the most commonly seen infections in captive amphibians. Usually diagnosed as “red leg” or “septicemia”, Aeromonas outbreaks cause hemorrhages leading to patches of red skin, often on the underside of the legs and abdomen. In advanced cases, the skin sloughs off, leaving large, open sores. Definite diagnosis is made by a culture of blood samples. Aeromonas is extremely contagious and transmitted by contact between animals or with the water or substrate in which infected animals were held. Be sure to wash your hands thoroughly after handling sick amphibians and to use separate nets and other tools for each cage. A number of medications are useful in treating Aeromonas infections, but only if the condition is caught early on.
If you suspect Aeromonas, a first step might be to lower the temperature at which your pet is held. Among temperate amphibian species (i.e. leopard frogs, Rana pipiens), temperatures of 39 to 41 Fahrenheit have been used to successfully treat infected animals.
Many other ailments that commonly afflict amphibians are caused by bacterial infection. Those caused by Micobacteria are particularlydifficult to treat, while Chlamydia infections usually respond well to medications such as Oxytetracycline. A. hydrophila is usually implicated it gas bubble disease, a complicated phenomenon that originates from environmental conditions. These and related microorganisms will be discussed in a future article.
Fungi are particularly adept at taking advantage of conditions, such as an unsanitary terrarium or depressed immune system, which might predispose an amphibian to attack. Fungal infections often occur secondarily to another health problem, and their presence should be suspected whatever a frog or salamander becomes ill.
At least 20 species of fungi in the genus Saprolegnia have been shown to cause illness in fish and aquatic amphibians. Symptoms are cottony growths on the skin, weight loss, regurgitation, difficulty breathing and, eventually, ulcerations that resemble “red leg” (see above). Saprolegnia is nearly always present in the aquarium, and usually becomes established on amphibians when the mucous covering is removed from the skin (one reason frogs and salamanders should be held in soft nets or with wet hands only).
This fungus survives poorly at temperatures of over 70°F, and responds well to benzalkonium chloride and a number of other medications.
Free-living amphibians are host to a wide variety of parasites, often with little ill effect. However, when stressed by a poor diet or improper environmental conditions in captivity, the immune system may weaken and open the way to a more severe infestation. Also, due to the close confines of captivity, parasites have a much easier time infecting, or re-infecting, animals than they do in the wild.
Routine fecal exams are very important in identifying and controlling parasites. Many are resistant to medication while in their egg or spore stage, and therefore you must be careful to follow your veterinarian’s recommendations as to re-treatment (often a two-week interval will be suggested). Some parasites, such as Oodinium pillularia (which also causes “velvet disease” in fish), Charchesium, and Vorticella respond well to baths in a 0.6 percent sodium chloride solution, while others, such as Trypanosoma diemictyli, nearly always result in fatalities.
Vitamin and Mineral Imbalances and Environmental Factors
Amphibians are extremely sensitive to pesticides, disinfectants, and a wide variety of chemicals that are very common in our environment and even in the pipes that supply water to our homes. Also, as with ourselves and all captive animals, good nutrition provides the foundation for good health. I will address these topics in a later article. For now, you may
I have been fortunate in having had the opportunity to experiment with a number of medications and environmental approaches in my quest to learn more about maintaining amphibians in good health. In a few cases, I have met with some success. Doing so, despite my lack of medical training, has made me realize the value of observation and reasonable experimentation in this area. I’ll write more about this in my next article, but for now please remember that this area offers great opportunities for interested hobbyists. Please write to me and share your thoughts and observations. A variety of articles on amphibian and reptile health, written by one of this field’s leading veterinarians, are posted at http://www.azeah.com/