The natural habitat of the green iguana, Iguana iguana, ranges from Mexico to southern Brazil. This species has also been introduced into some areas including Hawaii and southern Florida. Although all of the same species, there are regional and individual variations in size, color, scales and secondary sex characteristics that may be observed when comparing individual animals. The green iguana is an arboreal (living in trees) to semi-arboreal species, with long tails and sharp claws making them proficient climbers and well adapted to life in the trees. They are also excellent swimmers, a tactic they use to avoid predators.
Although small as hatchlings (7-10” from nose to tail), if cared for properly, iguanas can reach up to 6 feet in length as mature adults. During the first 3 years of life iguanas grow at an astoundingly rapid rate and will increase their body weight 100-fold from ~12 grams to ~1200 grams (2.5 pounds)! Mature iguanas may achieve weights of 10-15 pounds if cared for properly. This means that iguana owners must be prepared not only to provide the diet and care required to support such rapid growth, but also to provide increasingly larger cages/enclosures as they grow. The large size of mature iguanas and their dinosaur-like appearance are what draws many people to owning one. However, their large size may cause a problem for people with limited space in their homes and lead to inadequate care.
Green iguanas that receive proper care and diet may live 10-15 years in captivity. Greater lifespans may be achieved in the future as the understanding of dietary and husbandry requirements grows.
Although iguanas are sexually dimorphic (males and females differ in appearance), it can be very difficult to accurately determine the sex of an individual prior to sexual maturity (2 1/2 years). In general, males grow larger than females with taller and thicker crests over the neck and back, larger scales beneath the eardrum, broader jowls, and larger femoral pores that produce secretions that resemble scales. However, these characteristics may vary depending upon the region of origin and among individuals. Sexually mature males will often display a characteristic behavior of rapid head bobbing (up and down), while females may perform a series of side-to-side head movements.
Iguanas are fascinating, beautiful animals that can be very rewarding to keep as pets. However, there is an alarmingly high rate of surrender of iguanas to rescue organizations and shelters and even release into the wild (this is never an acceptable course of action). The majority of these situations are caused by inadequate information at the time of purchase regarding the cost, time and effort required for proper diet and care, or unrealistic expectations regarding “normal” behavior for a large mature iguana. Green iguanas are wild animals. The iguanas available in pet stores today are, at best, the second or third generation hatched in captivity. This means that they have not adapted to captivity in the sense that dogs or other domesticated animals have. Their behavior is driven primarily by instinct, so appropriate “pet” behavior will have to be taught and reinforced. While many iguanas lose their fear of humans and seem to enjoy interacting with their owners, some may remain fearful and never become truly tame. Time, patience and regular interaction are required to develop a well-adjusted, social iguana.
Hatchling iguanas are readily available at many pet stores for relatively low cost (~$20). However, the cost for the equipment necessary for proper care and housing can quickly reach $250-300. As the iguana grows, larger aquariums and cages will need to be purchased and can be fairly expensive. It is advisable to budget for these costs from the beginning, as improper diet and housing will inevitably lead to a sick iguana that may or may not recover, even after costly medical care.
Selection of a healthy animal is vital to the success of owning a suitable pet iguana. Iguanas that are sick at the time of purchase may not recover, even with appropriate husbandry and medical care. Domestic, captive-reared hatchling iguanas generally make better pets that imported or wild-caught animals. Imported iguanas are often exposed to disease, stress and crowded conditions, and are more poorly adapted to captivity. Start with a hatchling and avoid animals over two feet long. Check the body for any lumps along the limbs, under the skin, or along the jaw. Avoid animals that appear thin or listless. Look for rounded body and tail, clear eyes, and a vent that is free of caked feces and debris. It is usually best not to select an iguana that dashes frantically to the back of the cage when people approach. This type of personality is notoriously difficult to tame.
Most hatchling iguanas can be adequately housed in a 20-gallon aquarium, but will soon outgrow this small space. It is more cost effective to start with a 55 gallon aquarium that will be adequate until the iguana reaches 2 1⁄2 feet to 3 feet in length (usually at around 2 years of age). Once the iguana is 3 feet long, a larger cage must be purchased or built. An enclosure for a mature iguana should be at least 1 1⁄2 times the length of the iguana in length (~8’), 2/3 the length of the animal in width (~4’), and the length of the animal in height (~6’). Cages can be constructed of a variety of materials, and must be easy to clean and disinfect.
Iguanas should be provided with branches for climbing, and silk plants can also be used to provide visual appeal and shelter. A hide box is essential, especially for younger animals, and can be as simple as a cardboard box with a door cut in the side. Having a place to hide during times of stress is essential to their emotional well-being. Food and water dishes need to be heavy enough to avoid tipping, with ceramic crocks being ideal. Hot rocks are not recommended—they can cause serious burns.
The best substrate for iguana cages is newspaper, as it is inexpensive, clean, and easily replaced. Other acceptable alternatives include indoor/outdoor carpet, Astroturf, or alfalfa pellets (rabbit pellets). Avoid wood shavings, cat litter, gravel and sand, as these may be accidentally eaten by the iguana and are hard to keep clean and dry.
Maintaining adequate cage temperature is an essential part of keeping a healthy iguana. Overhead heat should be provided at one end of the cage in the form of a ceramic or incandescent bulb. The bulb must be covered by screening to prevent burns. The temperature beneath the heat lamp should be 90-95F, and can be monitored by placing a thermometer at basking height beneath the lamp. Additional heat can be provided on the same side of the cage using under-tank heaters, but these must be covered with a flat rock or ceramic tile to avoid burns.
Full spectrum lighting (both UVA and UVB rays) is necessary for iguanas to produce vitamin D and maintain a proper balance of calcium for strong bones and general good health. Natural sunlight is the ideal source of full spectrum light, and iguanas benefit from exposure to sun for 20-30 minutes several times a week during warm weather. This can be provided by placing the cage next to an open window (glass filters out essential rays), or providing an outdoor enclosure. A full spectrum reptile light should be placed over the indoor cage and kept on for 10 hours a day. Check packages carefully to be sure the bulb provides high levels of UVB rays (usually labeled specifically for reptiles).
Cages must be kept scrupulously clean and dry in order to prevent bacterial and fungal growth that can cause disease. Feces and old food should be removed immediately and the area cleaned with hot soapy water. Iguanas have nasal salt glands that allow them to “sneeze out” excess salt, and this will appear as a coating of white spots on the sides of the cage. These can be removed daily with a damp paper towel. The entire cage and accessories should be thoroughly washed weekly with hot, soapy water, rinsed, and then sprayed with a solution of dilute bleach in water (1:20 solution) that is allowed to sit 10 minutes and then rinsed.
Having an additional area for your iguana to “hang out” during the day or when interacting with people is a good idea. The pen should consist of an elevated platform with low walls, an overhead heat source, food and water dishes and branches for climbing and basking. The pen should be placed near a window so the iguana can enjoy natural sun through the open (screened) window during warm weather.
Green iguanas are herbivorous, or plant eaters, by nature. Vegetables should comprise the majority of an iguanas diet. Leafy green vegetables rich in calcium must be provided daily and include: collards, mustard greens, alfalfa, dandelions, bok choy, swiss chard, kale, turnip greens, escarole and green beans. A mixture of other vegetables should also be provided daily, including: romaine lettuce, frozen mixed veggies, squash, zucchini, sweet potatoes, bell peppers, carrots, sprouts, and okra. Broccoli, cauliflower, brussel sprouts and cabbage should be fed only in very small amounts because they may cause thyroid problems if fed too frequently. Fruits can be offered in moderation, but should comprise no more than 10% of the diet. All fresh foods should be cut into small pieces, chopped or shredded for hatchlings and juveniles, and offered in larger, bite-sized pieces for adults.
Several brands of commercial iguana pellets are available for feeding. No long-term studies have been performed yet showing the effects of feeding pelleted diets in iguanas, but they are generally considered to be a good source of nutrition. Pellets can be kept available in the cage at all times.
Because iguanas are herbivores, animal protein is not a necessary part of their diet. At one time, dog food was recommended for feeding pet iguanas, but we now know that dog food is too high in protein and low in fiber, causing organ damage and shorter lifespan.
Iguanas have very specific requirements for the proper balance of calcium in their diet. Calcium is essential for maintaining strong bones during rapid growth and for reproductively active females. However, over-supplementation of calcium, especially in mature males, can lead to organ calcification and failure. Hatchlings and juveniles should be given one pinch of powdered calcium supplement (Rep-Cal) sprinkled over their fresh food daily. Be sure the calcium supplement does not contain phosphorus, as excess phosphorus can inhibit the absorption and use of calcium. Older iguanas should be given 1 pinch powder per 2 pounds body weight twice a week. Females that are producing eggs should be supplemented daily.
Fresh water should be available at all times for drinking and bathing. A large ceramic crock works well and must be cleaned daily, or more frequently if contaminated with feces. Daily misting with warm water from a spray bottle helps maintain appropriate humidity within the cage (60-80%), facilitate normal shedding, and is enjoyed by many animals. Many iguanas also enjoy swimming in a bathtub of clean warm water, but care must be taken to clean the tub with soap, followed by dilute bleach solution, to prevent spread of bacteria from reptile to humans.
Newly purchased iguanas should be examined by a veterinarian within 48 hours of purchase, and occur on an annual basis thereafter.
Iguanas can carry intestinal parasites, and should have a fecal exam performed at each veterinary visit.
Most pet iguanas do not do enough climbing on rough surfaces to keep their claws worn down, and therefore must be trimmed on a regular basis.
Iguanas are very good at hiding signs of illness. Any iguana that appears obviously sick is dangerously ill. Therefore, it is essential that owners are well in tune with their iguanas and can pick up on subtle behavior changes that may indicate a problem. When in doubt, call your vet. Early intervention is usually much less expensive and much more rewarding than trying to treat later in the course of a disease.
All reptiles, including iguanas, can potentially harbor the bacterium Salmonella. This bacterium can cause severe gastrointestinal disease and septicemia in humans. Many animals carry the bacterium without showing any clinical signs of illness, and the bacteria in their feces that can infect others. Attempts to treat the carrier animal is often unsuccessful at clearing the bacterium, therefore proper hygiene is the best way to control the disease and prevent human infection. Always wash hands thoroughly after handling any reptile or cleaning the cage. Never use food preparation areas, such as kitchens, to bathe reptiles, or wash cages or dishes. Scrubbing with hot soapy, water followed by a dilute bleach solution (1:20) is effective at eliminating most bacteria in the environment. People at highest risk of severe infection with Salmonella include pregnant women, children less than 5 years of age, and immunocompromised individuals (AIDS patients, organ transplants, patients undergoing chemotherapy). These individuals should avoid contact with reptiles, and reptiles may not be appropriate pets in homes where these people reside.