Metabolic Bone Disease in Reptiles

Published: April 5, 2012

Unlike some veterinarians, I like dealing with reptiles. Not so much because I enjoy working with the creatures themselves (they’re certainly interesting, but I don’t really see their allure as pets), but because their diseases often stem from errors in their feeding or general care.

If we catch the problem soon enough, we can usually fix it pretty easily, much to the client’s and patient’s delight (if reptiles can be delighted).

Metabolic bone disease is an excellent example. Meat eating reptiles rarely develop the condition, but for reptiles that primarily eat plants and/or insects, it is a significant concern. Metabolic bone disease is caused by one or more of the following:

Low levels of calcium or vitamin D in the diet
High levels of phosphorous in the diet
Inadequate exposure to ultraviolet-B wavelengths of light, which normally promote vitamin D production and calcium metabolism within the body

The symptoms of metabolic bone disease vary, but most patients exhibit some combination of bowed legs; limping; hard lumps along the jaw, spinal column and legs; a soft, flexible jaw; and difficulty raising the body up off of the ground. If calcium levels in the reptile’s blood become too low, neurologic problems (e.g., depression, lethargy, twitches, tremors, hind end weakness and seizures) and death may occur. Turtles and tortoises develop misshapen scutes and shells.

Veterinarians can often diagnose metabolic bone disease based on a reptile’s history and clinical signs, but blood calcium levels and/or X-rays provide confirmation. Mildly affected reptiles will typically recover once their diets have been changed and/or their exposure to full spectrum ultra-violet light is increased. More severe cases may also require injections of vitamin D, calcium, and calcitonin (a hormone that controls calcium homeostasis); fluid therapy; nutritional support; and stabilization of any fractures that resulted from calcium leaching out of bone tissue.

Reptile owners need to pay very close attention to their pets’ diets and the conditions under which they live. Feeding our plant-eating reptiles foods that are high in calcium is very important. These foods include, but are not limited to, cabbage, bok choy, sprouts, okra, kale, alfalfa, berries, squash, and cantaloupe. Insect-eating reptiles should eat bugs that are sourced from a supplier who feeds the bugs a nutritious diet before they are sold, and owners should "gut-load" the insects before offering them to their reptiles.

Vitamin D and calcium supplements are also important, but care should be taken to avoid overuse. An excess of a nutrient is often just as dangerous as a deficiency. Reptiles that are most active in the daytime, and all species of tortoises and turtles need to have access to full spectrum ultraviolet light. Bulbs work in a pinch, but natural sunlight is best. However, never put a reptile in a glass or plastic cage in direct sunlight. They can quickly overheat and die.

Of course, preventing a disease is always better than curing it. Avoid metabolic bone disease and the resulting trip to the vet by making sure that you provide your reptiles with enough calcium, vitamin D, and full-spectrum ultraviolet light as a part of their day to day care.