'Red-leg' Syndrome in Amphibians

By PetMD Editorial on Sep. 23, 2008

“Red-leg” syndrome is a widespread infection seen in frogs, toads, and salamanders. It is recognized by the redness on the underside of the amphibian's legs and abdomen, and is generally due to Aeromonas hydrophila, an opportunistic bacterial pathogen. However, viruses and fungi may also cause similar reddening. Underfed, newly acquired amphibians that are kept in poor-quality water or other less-than-ideal environmental conditions are particularly susceptible to “red-leg” syndrome.


The reddening of the amphibian's legs and abdomen is due to the dilatation (or stretching) of the capillaries under its skin. The amphibian may even begin bleeding from the skeletal muscles, tongue or “third eyelid,” a protective skin fold under an amphibian's eyes. Other symptoms that may be observed include:

  • Anemia
  • Lethargy
  • Extreme weight loss
  • Open sores on the skin, nose, and toes that do not heal
  • Ascitis (collection of fluid in the abdominal cavity)


The bacterium Aeromonas hydrophila, which generally is the cause for “red-leg” syndrome, is found in contaminated food or water, and may also be airborne.



Your veterinarian will look for signs of widespread infection, which could include inflammation or dead cells localized in the liver, spleen, and other abdominal organs. Blood or body fluid tests to detect the presence of the infectious-causing organism is also typically done.



Treating “red-leg” syndrome will depend on the underlying cause of the disease. For example, if it is due to the Aeromonas hydrophila bacterium, your veterinarian will prescribe antibiotics for the amphibian. Follow the guidelines set by your veterinarian to get optimum results.

Living and Management

Seeking timely veterinary help is necessary to avoid an outbreak of this disease. If an animal does become affected, be sure to isolate it from other amphibians in the home and seek immediate veterinary care.


Maintaining a clean, hygienic living environment for the amphibian will go a long way toward preventing “red-leg” syndrome. As such, tanks should be cleaned regularly, so as to prevent organic matter from collecting.

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