Iguanas: Owning

The common green iguana is a large, arboreal lizard (meaning they live in trees and bushes) whose habitat ranges from central Mexico to Brazil, and includes the Caribbean islands. Iguana iguana is the scientific name for this species. 

Iguanas are herbivores (plant eaters) and require UV-B light to absorb calcium properly from their diet. They have a long tail (used as a whip, for self-defense) and a row of spines running down their back.

The iguana is a popular pet lizard, although their popularity has been declining in recent years, with the availability of smaller, easier-to-keep lizards (such as bearded dragons and geckos). 

Mature males (two years and older) are easily distinguished from females, as they have a significantly larger head and jowls, thicker neck, more developed spinal crest along their back, and larger/more pronounced femoral pores on the inner side of the thighs. These pores are openings of glands that are used for territorial marking behaviors.

Under proper conditions, adult male iguanas can reach 15–20 lb (7–9 kg) and can grow to 6 ft (1.8 m) in length. The average length for most indoor pet iguanas is 3–5 ft (1–1.5 m). Therefore, it is important to ensure a larger enclosure and adequate UV light exposure as the pet grows.

"Iguanas are not suitable pets for young children or young teenagers."

Iguanas reach sexual maturity by two years of age. Female iguanas can produce and lay eggs without a male, although the eggs will be infertile and will not hatch. With proper care, your iguana can live 10–15 years, although 25 years has been reported. Healthy young iguanas are bright green in color. Their color gradually fades to a brown, dull orange or grayish green as they reach adulthood.

Iguanas are usually friendly and harmless, but they can cause severe scratches with their long claws. If they are are wild caught or not socialized well, some iguanas (especially sexually mature males) may be aggressive and territorial. Some iguanas can inflict a painful, damaging bite if they are provoked or if they are protecting their environment. Iguanas are not suitable pets for young children or young teenagers. Iguanas are best suited for the skilled, knowledgeable reptile enthusiast.

How do iguanas differ from other pets?

Iguanas are unique pets in many ways.

• Iguanas do not have diaphragms. They use muscles located between their ribs (intercostal muscles) to help with breathing.
• Iguanas, like most reptiles, have a three-chambered heart. Dogs, cats, and humans have a four-chambered heart.
• Iguanas' tails may break off if they are handled roughly. If the broken section involves half the tail or less, the tail may grow back again. The newly formed tail will have a smoother texture and a duller color.
• Males have two reproductive organs called hemipenes. These are paired structures located on the right and left sides of the base of the tail.
• Iguanas have a renal portal blood system, where blood from the hind limbs is filtered by the kidneys before reaching the general circulation. This means toxins from the rear limbs (as could occur from wounds on the legs), as well as drugs injected into the rear legs, are probably filtered before entering the general circulation.
• Iguanas excrete uric acid as the main waste product of protein metabolism (dogs, cats, and humans excrete urea nitrogen). Uric acid is the crystalline, white portion of iguana excretions. This system allows iguanas to adapt to desert environments where water might be restricted. Unlike many reptiles, iguanas have a urinary bladder.
• Iguanas have a cloaca, which receives secretions from the urinary, gastrointestinal, and reproductive systems. The external opening of the cloaca is the vent, which is located on the under surface of the pelvis, just before the base of the tail.
• The skin is covered with scales and is usually shed in patches as the iguana grows, unlike snakes, where the skin is usually shed in one piece from head to tail.
• Iguanas explore their environment by flicking out their tongue and licking or "tongue-testing" with a light touch of the tongue. This sensory exploration is like sniffing.

How do I select an iguana?

Most owners buy iguanas locally from a reptile fair, breeder, or pet store. Online purchases have become more common over the past few years. Young, captive-raised animals make the best pets. Older imported animals are harder to tame, may harbor intestinal parasites, and often suffer from the stress of forced captivity. Avoid sick-looking animals. Always inquire about a health guarantee from the pet store, breeder, or online site.

Start out right with a healthy pet. Avoid lizards that appear skinny, have loose skin or sunken eyes, or appear inactive or lethargic. A young, healthy iguana is usually bright green, aware, active, and alert, as evidenced by the front legs pushing the chest and head upright and high. The tail by the back legs should be round, plump, and full, not sunken in and bony. The vent or cloaca should be clean and free of wetness or stool stuck to it.

If you can gently open the mouth (tapping lightly on the snout with a finger often works), you should see a small amount of clear saliva and a bright pink tongue and oral cavity. The tip of the tongue is a brighter pink than the base of the tongue. Mucus that is cloudy or "cottage cheese" in appearance is a sign of mouth rot, as is redness or pinpoint hemorrhages (small spots of bruising) on the mucous membranes.

My iguana looks healthy. Does he need to see a veterinarian?

Within 48 hours of your purchase, you should have your iguana examined by a veterinarian familiar with reptiles. The physical examination includes measuring the animal's weight, as well as checking for any abnormalities. The iguana should be examined for signs of dehydration and malnutrition. A fecal test should be performed to check for intestinal parasites.

"Like all pets, iguanas should have annual health examinations and fecal parasite checks."

Like all pets, iguanas should have annual health examinations and fecal parasite checks. Many veterinarians consider all iguanas (even those bred in captivity) to have pinworms, so your iguana may be routinely checked for these parasites and dewormed if necessary. These pinworms are not transmissible to people and are considered part of the iguana’s natural intestinal flora.

Your veterinarian will examine the oral cavity for signs of infectious stomatitis (mouth rot). No vaccines are required for iguanas. Your doctor may recommend blood tests, bacterial cultures, or radiographs (X-rays) to check for other diseases. Iguanas are known to be carriers of Salmonella bacteria.

If anyone in your household has immunodeficiency or is undergoing cancer treatment, it is highly recommended to get a stool culture to check for Salmonella and other bacteria that may cause human illness. To find a knowledgeable reptile veterinarian, go to https://arav.org.