The Green Iguana

The green iguana, scientific name Iguana iguana, continues to remain one of the most popular pet lizards in this country today. Over a half million hatchling green iguanas are imported into this country every year, most of which are captive bred in El Salvador. It's easy to see the appeal of these handsome lizards. They are beautifully colored, with a stately ridge of dorsal spines and large, expressive eyes. People that like lizards but find feeding live food distasteful like that green iguanas are vegetarians.

It tickles me to see iguana owners carrying a harnessed green iguana riding on the shoulder like a parrot. To me this truly signifies the attachment that an owner has to his pet iguana. Other lizard species may be somewhat high strung and unhappy about being handled, however, the green iguana often seems to really enjoy human interaction, and will often seek out human companionship for a bit of attention. Some iguanas like being scratched, some prefer gentle stroking on the head or on the dewlap, and others really seem to enjoy having dead, shed skin picked off from around the dorsal spines. (Please note that helping an iguana shed can be dangerous, as too vigorous of picking may remove or damage the live skin layer underneath the dead tissue, so this should only be carefully performed). Because the green iguana seems to often enjoy interaction with its keeper, the bond that develops is often a strong one.

Since I am a vet who works on iguanas, and I keep and breed them, I have had the privilege of knowing many fine pet iguanas. I also have a large enclosure for housing my iguanas outdoors during the majority of the year, since I live in Florida. One large male iguana that I acquired ten years ago, Bwana, is very tame and will accept food from any visitor's hand. One outdoor pen is used for breeding my pair, and I only pair them up during breeding season, which begins in April or May here in Florida.

Iguanas can often be allowed free run of a house or apartment, although I recommend that they be caged when not supervised. Iguanas usually urinate and defecate in water, so they can often be house trained by simply soaking them in warm water daily. This will keep the cage clean, requiring less frequent cleanings. Some iguanas do not regularly go in water, and may choose the same location to urinate and defecate in, and in these cases, it is easy to place newspaper in this area, facilitating clean-ups. Some people prefer to have an iguana as a pet because is so clean and quiet. Apartment and condominium dwellers may be able to have a pet reptile, but not a dog, cat or bird.

Green iguanas can recognize familiar people. The do seem to have definite preferences concerning people, although some rather gregarious iguanas will tolerate attention from anyone.

Because the are arboreal, they will usually choose to lounge as high up as they can. They are often found in trees in their native habitat, and they do like to climb. In the home, they will often climb up draperies and enjoy sitting on the curtain rod, or they may choose the back of a sofa as their vantage point. When designing a cage, it is important to keep this in mind, as they seem happier up off the ground, in many cases.

Choosing a Pet Iguana

Before purchasing an iguana for a pet, this decision should be well-thought out. Although the hatchling green iguana is just about the cutest little creature, it must be remembered that it is going to grow rapidly during the first two years of life, and will eventually attain a length of up to five to seven feet in length. Many iguanas will outgrow any caging that can be provided by the owner, and the end result is that the iguana will be sold, given away or turned loose when it grows too large to be managed.

Hatchling green iguanas are quite reasonably priced, but the conscientious owner will need to purchase the correct supplies and provide a cage of suitable size for the miniature godzilla.

Many green iguanas are imported into this country, and are captive bred on farms in Central and South America. However, due to their popularity, they are also being bred, in greater numbers each year, by hobbyists and serious breeders, in the United States. Either are acceptable as pets.

A hatchling iguana should be purchased from a reputable pet retailer or breeder. Many pet retailers now work with herp veterinarians to provide the proper medical care for the herps prior to their sale. In the case of the green iguana, this may mean that fecal parasite exams have been performed on the babies and that they have been given a physical exam prior to sale. Because roundworms (ascarids) are quite common in iguanas, many importers will routinely deworm the iguanas prior to importing them, and then again, once they have arrived in this country. As an added precaution, some pet stores will also periodically prophylactically deworm their hatchlings. Dosed properly, this is quite safe and is a good idea.

When choosing a hatchling or juvenile iguana, watch them in their cage first. Observe the hygiene of the cage itself and the pet store, in general. Note if an adequate diet is provided, and if clean water is available for soaking. Watch and see if the hatchlings are eating. Ask to handle the babies. You should choose an iguana that doesn't race away when you try to pick it up. A healthy baby should be plump, and the skin should not be wrinkled. It should be a vibrant green, not a dull brown or yellow color, and the skin should be free of black spots, ticks, cuts or scrapes. The eyes should be bright and clear. Check that all toes are present and examine the tail, which should be long and straight. Be careful to not restrain the iguana by the tail, or you may break it off.

Although you may be tempted to purchase more than one baby iguana, this is not a good idea. Iguanas are solitary animals that only come together for reproductive purposes. Even youngsters may demonstrate territorial displays, which is stressful to them, and may become dangerous to them as they mature and begin fighting or not allowing the more submissive ones to eat. For these reasons, they are better kept as solitary pets. If your goal is to breed them, juveniles will need to be housed separately as they mature.

When deciding to purchase an iguana, keep in mind that they can live for over fifteen years, so this is quite a commitment. If you are not concerned about purchasing a hatchling, you might be interested in adopting an older, larger iguana. These are often offered for sale in newspapers, as they have grown too large for unsuspecting owners. Some of these older iguanas make great pets, but keep in mind that some may have undesirable habits or may be aggressive, and that is why they are being sold or given away.

Does it make a difference if you get a male or female as a pet? It might. Females don't grow as large as males, and are often less aggressive as adults. They don't develop the tall, impressive dorsal spines that males do, and mature females may develop reproductive problems. I think that the females are more docile and make a better "hands-on" kind of pet, but for an impressive animal for a large display, a male is better. Several males should never be kept in the same cage, and if possible, not even in the same room to prevent territorial displays and acts of aggression, which may unfortunately be directed towards their human caretakers. Even a solitary adult male may become aggressive towards his owner. There have been several cases of mature males attacking their owners, inflicting severe damage to them, requiring medical care, and even plastic surgery. They can act very unpredictably and attack without warning. Although a mature female can also impart a serious bite, they are not usually as aggressive as the males, except perhaps during breeding season.

You should know that it is very difficult to determine the sex of a hatchling, and the technique known as probing should be saved until the iguana has grown some. Adult males have a distinct bulge on either side of the midline behind the cloaca from the hemipenes. They also are larger, have taller dorsal spines and enlarged femoral pores.


A hatchling iguana may be adequately housed in a 20 gallon aquarium, but since it is going to grow very rapidly during the first year, it is better to start out with the largest cage that it is possible to provide. A sixty gallon tank is better. Some people prefer to purchase cages designed specifically for herps, and these can work out very well. Others may choose to make their own cage out of wire or mesh, with a PVC, wood or metal frame. It is best to use newspaper or butcher paper to line the cage, or other substrates may be used, including rabbit pellets and indoor-outdoor carpeting. Gravel, sand, crushed shell, corn cob bedding or other material that could be ingested, resulting in impaction, should not be used. Some baby iguanas may nibble at carpeting as well, and if this behavior is observed, it should be removed from the cage.

The cage may be planted with non-toxic plants, if so desired. A shelf of some sort should be positioned high in the cage for basking. Natural branches and rocks may be used. A water receptacle can be placed in the cage or the iguana may be removed from the habitat for daily soaks.

Any cage should have a secured lid or door.

Light and Heat

There should be a source of light for basking, and this may be supplied by an incandescent light bulb in a clip-on shop light. The light must be placed and secured so that the iguana cannot burn itself while basking. A wide-spectrum fluorescent light should also be provided to provide daytime light and the necessary UVB ultraviolet light rays.

Even if wide-spectrum fluorescent light is provided (and it should be), an iguana should receive an hour of natural sunlight per week, at minimum. This sunlight should not be filtered through glass, plastic or fine mesh. The cage should not be placed near a window where filtered sunlight can heat the cage excessively. The light will not be beneficial, and can raise the ambient temperature to lethal levels.

The cage should have a focal basking spot of 100 degrees F, and a temperature gradient in the cage of from about 85 degrees F to 95 degrees F. The nighttime temperature can drop to about 75 degrees F. If the room the cage is kept in is too cold without lights, ceramic heaters can be used to provide heat without light.

It is important to purchase and use a good thermometer to accurately measure the temperature and humidity in the enclosure. If an iguana is consistently kept too cool, it will not be able to properly digest its food, and therefore, will not grow properly or thrive. Many stores sell a combination digital thermometer and barometer for less than $20. It is a wise investment.


Because green iguanas grow so rapidly during their first year, if they are fed improperly, or do not have correct lighting, they will become ill. Many improperly fed iguanas will develop metabolic bone disease, or nutritional secondary hypoparathyroidism. This will result in the iguana developing swollen limbs, a rubbery jaw and spontaneous fractures. It can be fatal if not treated and the lizard's diet is not corrected.

Iguanas are vegetarians, specifically, they are called folivores. This means that they consume primarily leaves in their natural environment. They are also hind-gut fermenters, which means that they require microbes to digest the high-fiber foods they ingest. Some older textbooks recommend that young iguanas would eat both vegetable and animal matter naturally, and this has been proven to be incorrect.

Although they are vegetarians, that does not mean that they won't develop a taste for inappropriate food items. I have known pet iguanas that were happy to share a bowl of popcorn with their owners, others that would sneak into the kitchen to eat cat or dog food, and one patient of mine was very fond of chicken hot dogs. Feeding an iguana anything other than vegetable matter or commercially prepared iguana food is dangerous and should be discouraged. Often, pet stores will recommend feeding a young iguana monkey biscuits or dog food, and this can cause serious problems, even death.

A high percentage of the iguana diet should consist of dark green, leafy vegetables. Eighty to ninety percent of the diet should be chosen from collard greens, turnip greens, mustard greens, bok choy, Swiss chard, clover, red or green cabbage, watercress, savoy, kohlrabi, dandelions, escarole, parsley and alfalfa pellets. Beet greens and spinach contain oxalates that may bind dietary calcium should be offered only occasionally. The same goes for kale, Brussels sprouts, broccoli, cabbage and cauliflower because these bind iodine and may cause thyroid problems. It is best to provide variety to the iguana's diet to prevent any nutritional deficiencies or excesses. The darker, outer leaves of most vegetables are more nutritious than the more pale, inner leaves. Iceberg, romaine, butter and Boston lettuces are all poor nutritionally, and should be fed sparingly, if at all.

Ten to fifteen percent of the diet should be chosen from frozen mixed vegetables (which are great to feed on those busy mornings), squash, sprouts, carrots, cooked sweet potato, cucumber, okra, parsnips, spineless cactus pads, asparagus, mushrooms, green and red peppers, peas, beans, corn and green beans. Backyard weeds and grasses can be offered as forage. Fruit should make up the remainder of the diet. Fruits are usually preferentially consumed, but most are mineral-poor. Figs are one of the only fruits high in calcium, and these, along with apricots and dates, may be relished.

Canned or dry commercial iguana diets can be offered on days when you don't have time to prepare the daily smorgasbord. Occasionally, they can be used as the entire daily diet, but it is better to combine them with some fresh food.

As treats, hibiscus flowers and leaves, rose petals, geranium flowers nasturtiums, carnations and dandelions can be fed. Life food is not necessary. Some iguanas relish crickets, mealworms and pinky mice, but these sources of animal protein are poor dietary items and should not be fed at all.

Some iguanas develop serious food preferences, so it is important that they consume at least ten different food items regularly, to avoid nutritional problems. It is a good idea to try to prevent iguanas from developing bad dietary habits, which may be difficult to break.

Iguanas require a diet higher in calcium than phosphorus, and foods and supplements offered should have a positive calcium to phosphorus ratio.

Many iguanas consume most of their dietary water from the moisture in the foods they eat. For this reason, make sure that you feed some juicy, moist items every day. The iguana should be soaked daily, as well.

The decision to provide a vitamin and mineral supplement is one that you should make with your herp vet, based on the evaluation of your iguana's diet and condition. It is possible to oversupplement, which can also be dangerous.

Veterinary Care

Iguanas have been implicated as carriers of the Salmonella bacteria. It may be a good idea to discuss this with your herp vet, who may want to perform some testing, although this is not always reliable.

Even if your new iguana appears healthy, it is a good idea to establish a relationship with a herp vet. The nails may need to be trimmed.

The green iguana is not for everyone, but for the person armed with the correct information regarding diet and husbandry, raising one can be very rewarding, and lots of fun, as well.

Dr. Wissman has co-authored the book
Green Iguanas : An Owner's Guide

Copyright 2006 Margaret A. Wissman, D.V.M., D.A.B.V.P.
All Rights Reserved

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