OHSU:Disease

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The information on this page is compiled with help from several Xenopus resource groups.

Frogs are typically a very hardy animal, but they still can, and do, become sick. You will see disease most commonly in stressed animals. Stressors include: overcrowding, improper handling, over use of the frogs, and/or poor water quality. It is important to keep the frogs that have just laid out (or have had surgery) in very clean water, at low density, and separate from the main colony. Keep sick or injured frogs isolated until you feel secure that the animals are healthy and will not infect the rest of the colony. It is advisable to boost the salt level to 20 mM. Frogs with severe lacerations extending through several dermal layers (post-op frogs for example) should have gentamycin (0.1 ml/l) added to the water.

If you find disease in your colony, just treating the symptoms will not solve the underlying problem. It is important, for the health of your colony, that you discover and treat the root of your problem.

A sick frog may display some or all of the following symptoms: remains at the top of the tank even when approached, clouds the water with shed skin, has tremors in its extremities, has open lesions, or bloats up. If your frog is in obvious discomfort from improper handling, or from escaping the water and being stranded and dry for a length of time, it is advisable that you euthanize it rather than allow the animal to suffer. You can easily euthanize in a 10% Benzocaine solution for at least one half-hour. You should then dispose of the body properly.

The following is a list of the most common frog diseases and their treatments. This is not a complete list, just what you will most likely encounter. As always, you should consult your institution’s Veterinary staff if you have concerns with your particular colony. Your best defense against disease in your colony is to be a very careful observer.

Contents

Nematode Infection (capillarid dermatitis)

Symptoms: Gray, rough, flaky skin, usually starting on the thighs. Excessive sloughing of skin. Rapid weight loss. If you did a skin scraping or necropsy, you would see nematode presence. The culprits are 2-4 mm, most commonly of the genus Rhabdias. This can be a life threatening disease and is highly contagious among stressed animals. It is very treatable if caught early on.

Treatment: Most effective if administered right away. We use Thiabendazole at 0.1g/L frog water. Treat the frog overnight. Change the water first thing the following day. Repeat. Keep the frog separate from the colony for several weeks to make sure she has fully recovered. The treatment is irritating to their skin so be sure to have a very tight lid on the container. You can also use Ivermectin, from PRO-VET (800) 435-6902. The dose is 0.2 micrograms per gram body weight (about 8 micrograms per male and 18 micrograms per female).

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Red Leg

Symptoms: "Red Leg" is the common name for a bacterial septicemia that causes high morbidity and mortality in frogs. Commonly implicated pathogens include: Aeromonas hydrophila, Proteus hydrophilus, and Pseudomonas hydrophilus. The causative agents are normal water flora that are opportunistic when animals have been stressed. By the time clinical symptoms occur, the condition is most often terminal. Mortality can be particularly high in newly acquired frogs. Sudden death, 2-4 days following infection onset, is quite common. In less acute cases, frogs are lethargic and refuse to eat. Cutaneous hemorrhages, especially on the skin of the legs and feet, subcutaneous edema, and trembling, initially in the limbs is common. Ulcerations may also be present. Infected Xenopus commonly show skin discolorations and heavy mucous secretion. Neurological disorder, ocular lesions and general edema may be present.

Treatment: It is only treatable if you catch this early on, otherwise you will lose the whole tank of frogs. Increase the salt concentration to 100 mM and add 100 micrograms per ml oxytetracycline to the water for a week. Try injected antibiotics (Tetracycline oral: 1mg/5g body weight for 5 days). Change the water every day. Isolate infected animals and all animals it had contact with. Keep a very careful eye on the rest of your colony.

Image:redleg.jpg


Fungal Infections

Symptoms: Frogs can become prey to several types of Fungus, especially in unclean tanks and when subjected to stress. The fungus may appear as: white cotton, wool like, thin stringy material emanating from a wound or reddened area of skin. Chromomycosis is caused by various pigmented fungi, while phycomycosis results from infection with Mucor or other nonpigmented fungi. Saprolegnia and other aquatic fungal infections may develop on wounds or on bacterial ulcers. Granulomas or abscesses may be found in any organ. Skin ulcers and nodules are also common.

Treatment: Fungus can be treated as long as there is not too much of it. Superficial lesions can be treated with topical antiseptics or fungicides. I suggest you try Anti-Fungal Tropical fish treatment or a product called Mar-Oxy which is sold in pet stores with fish supplies. Systemic infections may require sulfadiazine or imidazoles, but the underlying cause of the disease must be considered. Infection tends to recur once therapy is completed.


Dropsy "Bloating Disease"

Symptoms: Bloating Disease is characteerized by fluid accumulation under and between skin membranes. This is caused by a bacterial infection and is contagious. Early symptoms include: loose skin on the thighs and food regurgitation.

Treatment: This disease can be fatal but is treatable if caught early. Infected frogs should immediately be separated from other frogs. An Anti-Internal Bacterial, tropical fish treatment can be used.

Image:dropsy.jpg

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