Iguanas have several unique disease problems. Understanding these problems will allow you to better care for your pet and minimize future health care concerns.

Cystic Calculi

Cystic calculi, or uroliths, are commonly known as bladder stones. These stones occur when excessive dietary minerals form crystals in the bladder, which then bind to each other to form a concretion (a hard mass), otherwise known as a bladder stone. In iguanas, bladder stones are usually composed of uric acid, which may result from a diet that contains too much protein (such as a diet that contains dog food or cat food). Other causes of stone formation include deficiencies in vitamins A and D, calcium deficiency, excess oxalates (seen when feeding too much spinach), dehydration, or bacterial bladder infections.

As an owner, you may notice blood in the liquid portion of the urine or blood spots in the urates (solid fecal matter). Radiographs (X-rays) and a thorough physical examination, including physical palpation of the caudal (lower) abdomen, will allow your veterinarian to diagnose this problem.

Surgical removal of the stones will be necessary. Fluid therapy will be administered post-surgery to help prevent kidney damage. Your veterinarian will discuss dietary correction to attempt to prevent the formation of future stones. Antibiotic therapy may also be necessary post-surgery, as the damaged urinary bladder is more prone to bacterial infection.

Salmonella

While turtles are usually blamed for causing salmonella infections in children, iguanas are also a source of this potentially life-threatening bacterial infection. Salmonella is a zoonotic disease, meaning it can be transmitted from animals to humans. There are over 2,000 types of salmonella bacteria. An infection with these bacteria can cause severe gastrointestinal disease.

Symptoms of Salmonella in humans include nausea, vomiting, diarrhea, abdominal pain, cramping, fever and, in severe cases, septicemia (blood poisoning). Humans that are most at risk include children, the elderly, and the immunocompromised. Many animals, and some people, carry the bacteria in their intestinal tract without showing any clinical signs (called asymptomatic carriers), yet they shed the bacteria in their feces, which can infect others. As with any gastrointestinal disease, if symptoms last longer than 24 hours, consult a physician.

The best way to control Salmonella is prevention through proper hygiene. Thoroughly clean and disinfect the cage every time it is soiled. Clean up all feces right away. Use a separate cleaning area for people and reptiles. Most importantly, wash your hands thoroughly with disinfectant soap every time you handle, clean, or feed your iguana to help minimize the risks. Since most iguanas that carry Salmonella are not ill, they usually require no treatment. Treatment is often unsuccessful in killing all bacteria present in the intestinal tract.

Avascular Necrosis

Iguanas are often afflicted with a condition called avascular necrosis, in which the blood vessels supplying an area of the body become obstructed, causing the blood to stop flowing to the tissues. This condition leads to death of the affected tissue (necrosis), due to lack of blood supply.

In most cases, avascular necrosis occurs in juvenile iguanas kept in conditions of low humidity. Low humidity can lead to dysecdysis: difficult or abnormal shedding of the skin. Successive layers of un-shed skin can form rings around the toes and tail, restricting blood supply to the affected area and causing avascular necrosis.

"In most cases, avascular necrosis occurs in juvenile iguanas kept in conditions of low humidity."

The tips of the toes and end of the tail are the most affected tissues. Within a short time, the affected toe or tail may become infected and swollen or, more commonly, may become dry, black, and firm to the touch. A more concerning issue occurs when the necrosis or infection spreads up the tail or toe to surrounding areas of the body.

In other cases, blood vessels to the extremities may become damaged by traumatic injuries and subsequently become infected and swollen; a blood clot (embolus) may become lodged in the blood vessel; or a tumor may cut off the blood supply to the tail or toe. Sometimes the cause cannot be determined.

Treatment involves removing the "ring" of dead, unshed skin or, in severe cases, amputating the affected tail or toe to stop the spread of necrosis. Most pets recover well and lead normal lives after the surgery. Post-surgical antibiotics and anti-inflammatory medications may be required to help with potential infection in surrounding tissues.

Abscesses

An abscess is an infected swelling filled with pus. Abscesses are very common in iguanas. They occur when bacteria (most common) or fungi are introduced into the tissue by trauma, a bite wound, a penetrating foreign body, a tumor, or certain parasites. In reptiles, pus is usually caseous (cheese-like) and thick, like the consistency of cottage cheese. Abscesses that are subcutaneous (just under the skin) are common. Oral cavity abscesses cause a visible swelling on either the upper or lower jaw and may cause difficulty eating.

Abscesses are diagnosed by appearance, palpation (feeling), surgical exploration, or fine needle aspiration (a type of biopsy in which a sample is taken with a needle). Abscesses are treated by surgical removal or lancing (cutting open) and flushing of the abscess. The material in the abscess should be cultured (grown in an artificial environment like a Petri dish) to identify the organism causing the infection, which will help determine the appropriate medical therapy to use to eliminate the infection. 

Dystocia

Dystocia, or egg binding, happens when a female iguana is unable to pass her eggs. Green iguanas usually lay anywhere from 20 to 40 eggs but have been known to lay as many as 70. Egg binding is a relatively common problem in iguanas, as well as other reptiles, and can be life threatening. It is caused by a variety of factors. Most commonly, it is associated with improper environmental lighting and temperature, an inadequate nest site, improper diet (malnutrition), and dehydration. Other contributing factors include the age and condition of the animal, injuries, or physical obstruction caused by deformed eggs, oversized eggs, infections, constipation (less frequent bowel movements), abscesses, masses, and physical abnormalities of the reproductive tract or pelvis.

A normal, gravid lizard (a lizard with eggs) may not eat, but will still be bright, active, and alert. A gravid lizard with dystocia will be anorectic (have limited to no appetite) with a very distended (swollen) abdomen, and will become progressively more sick, lethargic (little to no energy), or unresponsive. If your iguana is not active and has a distended abdomen, it is very important that you have a veterinarian familiar with reptiles examine them. Your veterinarian will diagnose dystocia based on a physical examination and X-rays. Medical and/or surgical procedures will be necessary to treat these cases.