What are some common diseases of pet iguanas?

When iguanas are in a suitable environment, given a good diet, and provided exposure to UV (ultraviolet) light, they are reasonably hardy animals. Common diseases that may afflict pet iguanas include metabolic bone disease (MBD), fungal skin infections, infectious stomatitis (mouth rot), external (skin) and intestinal parasites, respiratory disease, ovostasis/dystocia, and hypervitaminosis D.

What are the signs of these diseases?

Metabolic bone disease (MBD) is a complex disease and probably the most common medical problem of pet iguanas. It is typically caused by feeding an improper diet that is high in phosphorus and low in calcium and/or vitamin D3 (from a nutritional deficiency), or from a lack of UV-B lighting or a lack of exposure to natural daylight. Common signs include swelling of the lower jaw, softening of the jaw and facial bones (rubber jaw), and/or swelling of the hind limbs. X-rays reveal thin bone tissue (decreased density), widened and thickened bone shafts, and possibly fractures that appear to have happened with minimal force or for no apparent reason. Green-stick or folding fractures may occur in soft bones that appear to bend or fold and not fully break apart.

Blood tests may show either a low calcium level or an elevated phosphorus level. The diagnostic feature is an abnormal calcium to phosphorus ratio. A normal calcium:phosphorus ratio is 2:1 or 3:1. As the condition progresses, muscle twitching, seizures, loss of appetite, and loss of energy (lethargy) occur. MBD is also known as fibrous osteodystrophy or nutritional secondary hyperparathyroidism. It is most seen in juvenile iguanas (less than two years old).

A common fungal skin infection that infects mostly young iguanas is CANV, which stands for chrysosporium anamorph of Nannizziopsis vriesii. CANV is often referred to as yellow fungus disease, although newer testing has identified other species of Nannizziopsis as the cause of yellow fungus disease, such as Nannizziopsis guarroi. The disease causes tan to yellow crusty skin lesions anywhere on the body. Advanced cases may show open bloody skin lesions. Treatment requires several weeks of prescription antifungal medication and, in some cases, the infection may be fatal.

Infectious stomatitis (mouth rot) is a bacterial infection that shows up as pinpoint hemorrhages on the gums, swollen gums, or an excess production of thick mucus in the mouth that often looks like cottage cheese. Mouth rot can also cause swelling of the jaw like MBD, but the swelling occurs only on one side of the jaw, in mouth rot. When there is swelling along the gumline or along the jaw bone, it is likely that a solid abscess has formed in the soft tissue of the gums.

Intestinal parasites, especially pinworms, are common in pet iguanas. These parasites often cause no clinical signs and are detected on an annual fecal examination. In some cases, they may cause diarrhea or weight loss. Pinworms are probably commensal organisms (commensalism is an association between two organisms in which one individual benefits from the relationship while the other is neither benefited nor harmed).

Mites and ticks are sometimes found on an iguana’s skin. These parasites are spread by direct contact with infected iguanas and are not from other pets or the cage environment. Mites and sometimes ticks can be seen moving around the body of your iguana, under or between scales, around the head, legs, and in skin folds.

Respiratory infections or pneumonia can occur in animals that are stressed, improperly fed, or kept in poor, cold, or dirty conditions. You may see sneezing, nasal or ocular discharge, bubbles in the mouth, unnaturally rapid or shallow breathing, gasping for breath, and lethargy (lack of energy).

Ovostasis refers to the inability to properly form eggs. Dystocia refers to the inability to lay eggs. Female iguanas can form and lay up to 40 eggs at one time. In cases where nutrition is inadequate, UV lighting is deficient or absent, or there is no space set up for a nest, the ovarian follicles remain in the reproductive tract and do not mature. The iguana cannot lay these immature eggs or follicles, creating a loss of appetite, distended abdomen, and weight loss. In cases of dystocia, the eggs are formed in the reproductive tract but are either unable to be laid or are in a holding pattern, waiting for the proper nutritional and environmental factors to be corrected.

Hypervitaminosis D is a condition that develops when owners either over-supplement the iguana's diet with vitamins and minerals or feed it dog or cat food. Clinical signs are vague and include lack of appetite and lethargy. Hypervitaminosis D often causes severe kidney damage, so a proper diet is essential to keep your iguana from succumbing to this problem.

How can I tell if my iguana is sick?

Signs of disease in iguanas may be specific to a certain disease, such as jaw or hind limb swelling with MBD. Any change in skin color or texture should be brought to the attention of a veterinarian knowledgeable in reptile medicine. If your iguana appears bloated, you need to have them seen by a veterinarian familiar with reptile medicine and surgery.

More often, signs of disease are non-specific, such as an iguana with anorexia (lack of appetite), depression, and lethargy, which can be seen with many diseases. Any deviation from normal is cause for concern and your iguana requires immediate evaluation by your veterinarian.

How are iguana diseases treated?

Any of these diseases can be severe enough to cause a loss of appetite and/or severe lethargy. Conditions of noticeable health issues need examination by a veterinarian knowledgeable in reptile medicine. Your iguana may require hospitalization and intensive care, which can include medications, fluid therapy, and force-feeding.

• MBD usually requires immediate treatment with injectable or oral calcium, a multivitamin or mineral supplement, and/or calcitonin, a drug that promotes calcium uptake in your iguana's bones. Long-term management of MBD requires provision of UV-B lighting and dietary modification.
• CANV requires oral anti-fungal and/or oral antibiotic therapy. Treatment may take weeks to months.
• Infectious stomatitis (mouth rot) usually requires injectable antibiotics, as well as antibiotic mouth rinses. Severe cases often require surgery to remove abscessed tissue.
• For internal parasites, several oral and injectable deworming medications are available. The type of parasite identified on the microscopic fecal examination will determine which drug is needed. Mites and ticks can be treated topically or with oral or injectable medication, as directed by your veterinarian. Environmental treatment, cleaning, and disinfecting may also be required.
• Respiratory infections will be investigated with X-rays, blood tests, and cultures. They will likely be treated with oral or injectable antibiotics. If they are severe, the animal will have to be hospitalized for more aggressive therapy and support.
• Cases of dystocia in female iguanas may be resolved by correcting dietary and UV lighting deficiencies, along with offering a sandy area for burying eggs. If your iguana is unable to lay her eggs, surgery will be required to remove the immature eggs and the reproductive tract.
• Hypervitaminosis D is a serious problem that requires hospitalization and intensive therapy with fluids, force-feeding, and drugs to help lower the iguana's calcium level. Dietary modification is necessary for long-term treatment.