Reptiles: Gout

By Gregory Rich, DVM; Rick Axelson, DVM

What is gout?

Gout is a disease in which the metabolism of uric acid is defective. Uric acid is a breakdown product of nitrogen, formed when protein is metabolized in the body. Reptiles excrete nitrogen waste as uric acid, which is removed from the circulating blood by the kidneys. In gout, this uric acid is not eliminated effectively.

Gout is a common problem in many reptiles, including terrestrial turtles. Although they are reptiles, aquatic turtles excrete the majority of their nitrogenous wastes as urea or ammonia and produce only a small amount of uric acid, so they are not usually affected by gout.

How does protein play a role in gout?

All reptiles require dietary protein. Carnivores (meat eaters) require animal-based proteins and herbivores (plant eaters) require plant-based proteins. Proteins are made up of amino acid building blocks, and amino acids are an essential nutritional component of many bodily functions. Each different source of protein contains different levels of various amino acids, and each species of reptile is physiologically adapted to utilize the proteins and amino acids found in its natural diet.

"Each species of reptile is physiologically adapted to utilize the proteins and amino acids found in its natural diet."

The reptile's ability to manage uric acid depends on the amount of protein fed, the type of protein fed, the frequency it is fed, and the hydration status of the body. If uric acid is not excreted, it may accumulate in the joints, in the kidneys, or around other organs such as the liver, spleen, heart, or lungs. Sometimes, uric acid may accumulate in mucous membranes, such as the mouth. Gout is classified as either articular (joint) gout or visceral (internal organ) gout.

What causes gout in reptiles?

This is not entirely clear, but diets too high in protein or containing inappropriate proteins are a predisposing factor. Dehydration and altered kidney function are also key factors. In the case of starvation, an animal will utilize its own bodily resources, including proteins, for energy, which can lead to gout.

What are the signs of gout and how is it diagnosed?

Raised cream-colored masses may be noted on the joints of toes, ankles or wrists in cases of articular gout. Typically, patients have trouble moving around because of joint pain and swollen joints. The mucous membranes of the oral cavity may have raised, whitish, spherical swellings (gout tophi).

Your veterinarian will gather a thorough history, perform a physical examination, evaluate the diet and environment (including water availability, humidity and temperature), and may recommend blood tests and/or x-rays to diagnose gout. On x-rays or physical palpation, the kidneys may be enlarged. A blood uric acid test will be performed and, in some cases, a swelling may be lanced and the material in the swelling analyzed under the microscope, for evidence of uric acid crystals.

How is gout treated?

Dietary management or modification is the primary focus of treatment, along with correcting environmental deficiencies. The animal may be hospitalized for proper hydration (fluid therapy) and supportive care. Surgery is occasionally used to "clean out" the joints; in severe cases, the damage to the joints is enormous and irreversible.

"Surgery is occasionally used to 'clean out' the joints."

Medications used to treat gout in humans have been used in reptiles with gout, but success is variable and treatment may be lifelong.

What is the prognosis for a reptile with gout?

In many cases, treatment must be continued for the remainder of the patient’s life. In general, the prognosis for reptiles with a severe case of gout is very poor. The goal is to try and achieve a good quality of life through use of pain medication, proper hydration, dietary changes, and environmental modifications. In severe cases, euthanasia is an option to consider.

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