Susan Horton, DVM
Green iguanas are very popular pets. They are perhaps one of the most misunderstood and poorly kept of all reptile pets. They can reach considerable size. Recorded weights and lengths of adult male iguanas have been as much as 20 pounds and 7 feet respectively. Certainly not every iguana will become such a giant. But when considering an iguana’s environmental needs, such size factors should be taken into account. They also have specific temperature, humidity, lighting, and dietary needs. These topics will be covered in this handout. At the end of this handout, a list of informative green iguana books is provided.
With daily handling, iguana (also called, “iggies”) hatchling and juveniles can be transformed from flighty creatures into calm pets. However, the power of this species should never be underestimated once adulthood is reached! These lizards are relatively large in maturity and can cause severe injury if not properly handled and respected with their tails, nails, and bites. Iggies, although well tempered, are given up frequently due to their size, habitat requirements, and their temperament. This is at least a 10 year commitment and a hefty financial investment as well.
Reptile rescues and local zoos are constantly asked to accept relinquished iguanas and most no longer accept these animals. Please, consider adopting an adult or juvenile from a reptile rescue.
This New World species of lizard is found primarily in Mexico down to Brazil and has been introduced toHawaii and South Florida where they are now considered nuisance animals. This species has also been introduced to the Lesser Antilles region where it competes directly with the population of native iguanas. Despite the iguana’s ability to thrive and reproduce in introduced areas, this species is declining in native habitats due to habitat destruction, their use as leather and food, and the pet trade.
This is a long lived species averaging about 10-16 years with some living up to 25 years. In captivity, they can thrive and grow from a hatchling to a large adult in 3-5 years. It is well known now that this species requires optimal ultra violet radiation B (UVB) exposure as well as high quality diets.
Keep in mind your cute little hatchling iguana will someday be much bigger. You may start with a small 20-gallon aquarium now, but one day you will need a custom cage or room dedicated to his reptilian needs. Surfaces of your chosen enclosure should be smooth. Iguanas will rub their scales off their noses and hurt their feet if their enclosure is made of wire. Wood may be used so long as it has been sealed with exterior polyurethane varnish (such as marine varnish or similar). Allow the coating to cure for several days and air it out well before inhabiting it. Molded plastic and acrylic cages work well until the iguana out grows them. Iguanas should never be kept loose in the house. There are to many dangers this way, such as animal attacks, accidental injuries, and chilling.
Your iguana will need branches to climb on. Chose branches of appropriate diameter and strength to support his weight. Branches from outside can bring in pests. I suggest either baking at 320 for 20 minutes or drying out over the outdoor gas grill for 30 minutes. Keep branch away from flames (for the obvious reasons). Choose hard wood always. Pine and cedar will smoke heavily when baked! I usually use maple or oak.
Security is especially important for small iguanas. For these little guys I suggest covering half the exterior of the cage with paper or towels to provide a safe refuge from perceived predators (i.e. you, the dog, the cat, etc). Eventually you can remove this covering, once the little guy has acclimated to his new surroundings (6 months or so). Silk plants may look nice in the cage, but most iguanas will eventually try to eat them. They can be placed outside the cage instead.
I recommend newspaper or outdoor carpet. Newspaper should be changed often. If you choose outdoor carpeting, have several pieces. This way you can be sanitizing one and still have another to place in the cage. I do not recommend any particulate bedding, (corncob, wood chips, wood shavings, etc.). It is swallowed easily by iguanas. Intestinal blockage will lead to death if not addressed quickly. Particle bedding also hides a mess well. The moisture from spilled water, feces and urine build up in particulate bedding and will promote bacterial infections in your iguana. Reproductive females will require a dig box to stimulate egg laying and prevent behavioral retention. Dig boxes are designated areas or enclosed sections of top soil that can go as much as 2 feet deep!
An iguana can not digest properly or have a competent immune system with out the ideal heat. He is an ectotherm, which means he is the same temperature as his surroundings. The preferred optimum temperature zone (POTZ) temperature for green iguanas is 85°F to 95°F. The ideal nighttime temperature is 80°F-85°F. A gradient within the enclosure is ideal. This way the iguana can heat up and cool down as his body requires. Maintaining temperature is difficult. Most enclosures require a heating mat applied outside the cage with a thermostat to maintain nighttime temperatures. For basking, a reflector with appropriate wattage bulb will do. A branch should be provided under the bulb. For iguana rooms, a space heater can be used. Build a protective barrier around it so the iguana can’t get burned. Protect your iguana from burns by using a thermometer to figure out the high and low temperature areas of your cage before you place him in it. Never allow the iguana to touch the heat mat or bulb directly. Severe burns will occur. Hot rocks are not appropriate. Your iguana is a basker, meaning he gets his heat form basking in the sun. The hot rock will not heat the enclosure and will promote burns and dehydration for your iguana. Do not place a glass enclosure in direct sunlight. It will overheat and cook your lizard. Lights should go off at night. I use timers on my lights.
Humidity and water
Iguanas should be provided with a large water bowl. I recommend a large lasagna pan or cat litter box. It must be cleaned daily. Iguanas generally use their water bowl as a toilet, thus requiring frequent changes. Humidity is difficult to maintain in most iguana enclosures. Daily misting will help. Soaking in the bathtub weekly is also a good idea. The tub should have warm water to iguana shoulder level. Allow him to soak for about 20 minutes. Never soak a weak or debilitated iguana without complete supervision. The enclosure should never have condensation on the walls. This means you need more ventilation or your cage is too wet. Skin infections often occur when the enclosure is excessively moist. A hygrometer will read the ambient humidity. Iguanas need 65-75% at least. Coming from the rainforests of South America , these lizards should ideally be maintained at 80-95% relative humidity. Humidity can be maintained with large water bowls or bins, misting systems, foggers, humidifiers in large enclosures, and spraying the enclosure 2-3 times a day.
Ultraviolet Radiation B
This is a one of the key elements in keeping a healthy iguana. Reptiles produce vitamin D in their skin through exposure to UVB radiation. Vitamin D is important in calcium metabolism. UVB wavelength measures 290-320 nm. When purchasing a UVB source, check to make sure it provides this wavelength. There are several fluorescent bulbs to choose from. Repti-sun fluorescent bulbs or mercury vapor bulbs produce adequate UVB. The mercury vapor bulbs produce heat as well as UVB. They are very intense and penetrate 2 to 3 feet into an enclosure and up to 12 feet with increased wattage. The amount of UVB will be diminished or blocked if it passes through glass or plastic. I recommend placing it on screen material. The iguana should be no more than 12 inches from the fluorescent bulb. Exposure time should be 8 to 10 hours daily. Fluorescent bulbs need to be replaced every 6 to 9 months because the UVB production stops about then. I date my bulbs with a permanent marker to keep track of replacement times.
This is another key to keeping healthy iguanas. What you feed your iguana will determine its lifespan. Proper nutrition from the start will ensure healthy bones and kidneys. All food materials should be adequately washed, chopped and mixed. Young iguanas need their food finely chopped. They may be fed twice daily. As they age, feeding frequency decreases to once a day, then every other day for adults (3 feet and longer). Ingredients for sub-adult meals should include items from these categories:
- Calcium rich vegetables: 40-50% of diet, 2 or more items per feeding-turnip greens, mustard greens, beet greens, kale, collards, bok choy, Swiss chard, dandelions, parsley, romaine, spinach, and escarole. Spinach must not be over used as it binds iodine and calcium.
- Other vegetables: 30-40% of diet, a variety weekly. Frozen mixed vegetables, squash, zucchini, sweet potato, bell pepper, broccoli, peas, beans, okra, carrot, and pumpkin.
- Grain/fiber: up to 20% of diet. Boiled rice, boiled pasta, whole grain breads and cereals.
- Fruit: contain mostly fructose and fiber. It dilutes more valuable nutrients in other food items, so minimize its use. Figs, papaya, melon, apple, peaches, plums, strawberries, tomatoes, banana (with skin), grapes, kiwi.
- Legumes: more important for young iguanas, up to 5% total diet. Boiled lentils, navy beans, pinto beans, kidney beans.
Adult Iguanas are primarily fed the calcium rich veggies with small amounts from the rest of the list periodically. Senior Iguanas are primarily calcium rich greens.
Vitamin supplementation is most important in to growing iguana. A multivitamin supplement should be used twice weekly. Examples include Reptivite (Zoo-Med), Reptical (Tetra), Nekton, and human Centrum. A straight calcium supplement should be used 4 to 5 times weekly. This supplement should contain no phosphorus and does not need vitamin D. Iguanas seem to be unable to absorb vitamin D well from their diets.
* Older iguanas (adults) require a multivitamin once to twice monthly. Calcium may be given once weekly.
It is an old industry practice to feed iguanas, especially very young ones, animal or insect proteins to meet the dietary protein requirement. The belief was that if an iguana would eat the food then it must not be inappropriate. This information is outdated and has proven to be exceedingly harmful in many cases to this species. Yes, in the wild an iguana may happen upon a few insects on their plants or ingest some carrion but this is not the norm and is not done on a scheduled basis. Do not feed iguanas insects, dog food, cat food, or animal protein as this can lead to very serious and costly health issues in the future as well as death if uncorrected.
Cage cleaning should include thorough scrubbing and disinfecting. For washing, use non-toxic soaps such as dish soap. Rinse well. For disinfection, dilute bleach (1:10), chlorhexadine, or roccal (Upjohn, Kalamazoo). These must be rinsed very well. Allow cage to air out well before iguana is returned. Daily removal of food is important.
Finding ways to keep green iguanas entertained and active is as simple as rolling grapes across the floor or as complicated as modifying wiffle balls to hold fruit for them to move around. Creativity is essential for excellent iguana keeping. Tree trunks, tree branches, and root stocks make excellent obstacles, hides, and climbing surfaces. Make sure that there is a variety of climbing surfaces with some being more horizontal and others being more vertically oriented as this species is known for being agile climbers but enjoy ledges to rest on. Large soaking basins or every other day soaks in a kid pool or large rubber maid offers enrichment and another way to exercise iguanas. Hide boxes are also a requirement for young iguanas to feel secure in their enclosures. Although it is offering a place to retreat, this is a form of enrichment as well. The addition of clean untreated fall leaves, flowers, and other novel natural items offers an easy source of enrichment as well.
Green Iguana Society www.greeniguanasociety.org
Iguana Iguana: Guide for Succesful Captive Care, Frederic L. Frye
Green Iguana: The Ultimate Owner’s Manual, James W. Hatfield III
Iguanas in Your Home, R. M. Smith
The Green Iguana Manual, De Vosjoli, P. Lakeside, Ca, Advanced Vivarium Systems, 1992
Iguanas for Dummies, M. Kaplan. IDG Books
If you have any questions, please feel free to call us at (502) 241-4117.