Iguanas have several unique disease problems. Understanding these problems will allow you to better care for your pet and minimize future health care problems.
Cystic calculi, or uroliths, are commonly known as bladder stones. These occur when excessive dietary minerals form crystals in the bladder, which then bind to each other to become bladder stones. In the iguana, 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. A thorough physical examination that includes physical palpation of the caudal (lower) abdomen and radiographs (x-rays) 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 (see handout "Iguanas:Feeding") in an attempt to prevent future stones from forming. Antibiotic therapy may also be necessary post-surgery as the damaged urinary bladder is more prone to bacterial infection.
While turtles are most commonly blamed for causing salmonella infections in children, it has recently been determined that iguanas are also a source of this potentially life-threatening bacterial infection. Salmonella is a zoonotic disease, meaning that 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 in humans range from simple nausea and vomiting to 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 people carry the bacteria without showing any clinical signs, yet shed the bacteria in their feces, which can infect others (called asymptomatic carriers). As with any gastrointestinal disease, if symptoms last longer than 24 hours, consult a physician.
"Salmonella is a zoonotic disease, meaning that it can be transmitted from animals to humans."
Prevention through proper hygiene is the best way to control the disease. 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 (and treatment is often unsuccessful in killing the bacteria).
Iguanas are often afflicted with a condition called avascular necrosis, in which the blood vessels supplying an area of the body become obstructed. This leads to death of the affected tissue (necrosis), due to lack of blood supply. In most cases, this problem occurs in juvenile iguanas kept in conditions of low humidity. Low humidity can lead to dysecdysis (difficulty or abnormal shedding of the skin). The tips of the toes and end of the tail are most commonly affected. Successive layers of unshed skin can form rings around the toes and tail, restricting the blood supply to the affected area and causing avascular necrosis. Within a short time, the affected toe or tip of the tail may become infected and swollen or more commonly, may become dry, black, and very firm to the touch, Necrosis or infection can spread up the tail or toe to surrounding areas of the body.
"The tips of the toes and end of the tail are most commonly affected."
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 in an effort to stop the spread of the necrosis. Most pets recover well and lead normal lives after the surgery.
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. Subcutaneous (just under the skin) abscesses are frequently encountered. Oral cavity abscesses cause a visible swelling on either the upper or lower jaw and may cause difficulty eating. Reptilian pus is usually caseous and thick, like cottage cheese (not liquid). Abscesses are diagnosed by appearance, palpation, fine needle aspiration, or surgical exploration. They are treated by surgical removal or lancing (cutting open) and flushing of the abscess. The material within the abscess will usually be cultured (grown in an artificial environment like a Petri dish) to identify the organism causing the infection. This will help determine the appropriate medical therapy to use for eliminating the infection.
Dystocia, or egg binding, happens when a female iguana is unable to pass her eggs. Green iguanas usually lay anywhere from 20-40 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 poor husbandry, including 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, physical abnormalities with the reproductive tract or pelvis, infections, constipation (less frequent bowel movements), abscesses, or masses.
A normal gravid (with eggs) lizard 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 becomes progressively sick, lethargic (has little to no energy), or unresponsive. It is very important that you have a veterinarian familiar with reptiles examine this animal. A physical examination and x-rays are used to diagnose dystocia. Medical and/or surgical procedures will be necessary to treat these cases.