Iguanas: Owning

The common green iguana is a large arboreal (meaning they live in trees and bushes) lizard whose habitat ranges from Central Mexico to Brazil and includes the Caribbean Islands. Iguanas are herbivores (plant eaters) and require UV-B light for proper calcium absorption from the diet. They have a long tail (used as an effective whip, for self-defense) and a row of spines running down their back. The iguana is a popular pet lizard, although their popularity is on the decline in recent years with the availability of smaller, easier-to-keep lizards (such as bearded dragons and geckos). Mature males (2 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 males 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, proper provisions must be made for a larger enclosure and adequate UV light exposure as the pet grows.

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

Sexual maturity is reached by 2 years of age. Females 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 fairly docile and harmless, but can cause severe scratches with their long claws. If not socialized well or wild caught, some individuals (especially sexually mature males) may be very aggressive and territorial and if they are provoked, inflict a nasty, painful, damaging bite. Iguanas are NOT suitable pets for young children or young teenagers. Iguanas are better suited for the skilled, knowledgeable reptile enthusiast.

How do iguanas differ from other pets?

Iguanas do not have diaphragms. They use muscles located between their ribs (intercostal muscles) to help with breathing.

Iguanas have a three-chambered heart; dogs, cats, and people have four chambers in their hearts.

Iguanas' tails may break off if roughly handled. The tail may grow back again if the last half is cut off (called autotomy). 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 side 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, would probably be filtered before entering the general circulation.

Iguanas excrete uric acid (the crystalline, white portion of their excretions) as their main waste product of protein metabolism (dogs, cats, and humans excrete urea nitrogen). This allows them to adapt to desert environments where water supply might be restricted. Also, 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 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 the tongue and licking or "tongue-testing" with a light touch of the tongue. This is like sniffing and is a sensory function.

How do I select an iguana?

Most owners buy iguanas locally from a breeder or pet store. 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 or breeder.

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 and bony. The vent or cloaca should be clean and free of wetness or stool stuck to it.

"Start out right with a healthy pet."

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?

"Iguanas may be a carrier of the salmonella bacterial organism."

Within 48 hours of your purchase, your iguana should be 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. 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 species of pinworms are not transmissible to people and are considered to be part of the natural intestinal flora.) The oral cavity is examined 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 one of the species of reptiles that can be carriers of salmonella bacteria. Like all pets, iguanas should have annual health examinations and fecal parasite checks.

** If anyone in the household has any immunodeficiency or undergoing cancer treatment, a stool culture to check for salmonella and other bacteria that may cause human illness is highly recommended.** To find a knowledgeable reptile veterinarian, go to ARAV.org and search ‘Find-A-Vet’ under OWNERS.

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