Natural History   Nutrition   Hygiene   Visual Security   Heat Source 
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Natural History

Natural History The green (or common) iguana (Iguana iguana) is an aboreal (tree-living) and diurnal (daylight active) lizard found at elevations usually than 3,000 feet in tropical and subtropical regions from northern Mexico to central South America. It is most often found in the vicinity of rivers and streams.

Iguanas possess four short, powerful limbs equipped with strong claws (for climbing and digging) and a long strong tail. They are capable of reaching lengths of 6 to 6 1/2 feet (1 .8-2 metres). A large flap of skin (the dewlap) hangs from the throat and aids in regulation of the body's temperature. Iguanas also possess a prominent crest of soft spines (longer in the males) that are arranged along the midline of the neck and back, beginning at the base of the skull. Male iguanas tend to be larger and possess brighter overall coloration than females. The latter distinction is especially pronounced during the breeding season. Males tend to have larger heads than females, in part because of swollen jowls. Male iguanas also possess 12 to 13 prominent pores arranged in a row on the underside of both thighs.

An iguanas' skin is entirely covered with very tiny scales. Iguanas cannot change their coloring (as chameleons do) but certain areas of their skin can become darker when exposed to direct sunlight. Young iguanas are pale green with black ringed tails. They mature to a lighter more earthy color, usually, with dark vertical bars on the body and tail.

Vision, hearing, and the sense of smell are acute. In their natural environment, iguanas tend to be very wary, hiding or fleeing at any sign of danger. Iguanas are somewhat clumsy, but accomplished tree climbers. They tend to bask by day on branches of trees, often over water. When frightened or threatened, they will usually drop (sometimes from great heights) into the water below. Being excellent swimmers, they quickly make their way to protective cover by pressing their front limbs along their sides and swishing their powerful tails from side to side, with rear limbs trailing behind. Iguanas are also capable of safely landing on the ground and running to protective cover after jumping from substantial heights when threatenedand/or cornered, iguanas can defend themselves with astonishingly quick, whip-like lashes of their tails and with their claws and jaws.

The iguana mates in January or February. After a gestation period of about 2 months, the female excavates a hole in moist sand or soil, usually near the base of a tree, and deposits from 25 to 40 eggs. The hatch-lings, measuring 25 to 30 centimeters, emerge in about 2 weeks, they grow 15 to 24 cm. per year and attain sexual maturity in about 3 years.



Nutrition

Recommended diet for captive iguanas:
All plant material is washed, chopped (a food processor is recommended), and thoroughly mixed. This will ensure a balanced diet in that all food items will be eaten, rather than just the favorite tasty ones. Prepare enough for 4-7 days, store in the refrigerator between feedings, and serve at room temperature or slightly warmer.

Hatchlings up to 14 inches in length:
feed twice a day or provide continuous availability
plant matter: finely chopped or shredded

Juveniles up to 2.5 years or 3 feet in length:
feed once a day
plant matter: fine to medium chopped or shredded

Adults over 2.5 years or 3 feet in length:
feed daily or every other day
plant matter: coarsely chopped


Ingredients:
***EACH MEAL must contain ingredients from EACH of the FIVE of the following categories*** :

1. calcium rich vegetables:
30-40% of the diet, two or more items per feeding -turnip greens, mustard greens, beet greens, kale, collards, bok choy, Swiss chard, dandelions, parsley, romaine, escarole, spinach, dark green leafy vegetables, alfalfa pellets (soaked and ground).

2. Other vegetables:
30-40% of the diet, a variety weekly - frozen mixed vegetables, squash, zucchini, sweet potato, bell pepper, broccoli, brussel sprouts, peas, beans, okra, grated carrot, sprouts.

3. Grains/fiber:
optional up to 20% of the diet - whole grain breads and natural bran cereal.

4. Fruits:
no more than 15% of the diet - figs (high in calcium), papaya, melon, apples, peaches, plums, mangos, strawberries, tomato, banana ( with skin), grapes, kiwi.

5. Vitamin/mineral supplementation:
is advised because vitamin and mineral defidencies are common in Iguanas. However, calcium and fat soluble vitamins (A, D, E and K) can be over supplemented as well as under supplemented. To avoid over supplementation, natural sources from a varied diet are the best choice, with moderate vitamin/mineral use to balance the diet. To date, there are no documented studies on specific requirements for any lizard species.


Minerals:
use powdered calcium carbonate or calcium gluconate. mix 1 part vitamin and 2 parts mineral.

Hatchlings and juveniles: 1 small pinch per feeding

Adults: 1 full pinch per 2 Ibs body weight twice a week

Adult females: 1 full pinch per feeding from December to egg laying

Groups: 1/8 tsp. vitamin/mineral mix per 3 lbs Iguana/week.

* A comment on animal protein sources:
this is a highly controversial area. Traditionally, animal protein sources have been recommended in the diets of iguanas. However in the wild they are folivores, a type of vegetarian that eats primarily leaves. Some Iguana books falsely claim that Iguanas eat insects until they mature, then switch to a vegetarian diet as adults. This is not the case. They are vegetarians from birth even though they might occasionally accept unnatural foods in captivity. Protein should be supplied as a plant based source. Dog food, cat food, trout chow, crickets, mealworms should be excluded from the diet.

* A comment about canned, frozen or other commercial iguana diets:
the advantage of these products is that they are easier to use than preparing a balanced salads several times a week. The disadvantage is that in spite of claims that the commercial diets are complete and balanced, they may not be so. Commercial diets are unproved. They may have a role in iguanas nutrition but should only be part of the diet until more is known.

* A comment on oxalates:
oxalates occur in spinach, rhubarb, cabbage, peas, potatoes and beet greens. Oxalates bind caldum and trace minerals, inhibiting their absorption. Mineral deficiencies can occur if diets contain mostly these foods and mineral intakes are marginal.

* A comment of Goitrogens:
goitrogens occur in cabbage, kale, mustard and other cruciferous plants. Large intake of these foods with marginal iodine intake may lead to hypothyroidism.

Reference:
Reptile medicine and surgery, D.R.Mader, M.S, DVM. June 1996

Hygiene

Next to adequate nutrition, there is no other aspect of husbandry for captive reptiles more important than sanitation and hygiene. A large proportion of the bacterial and fungal diseases of captive reptiles result from their daily exposure to feca contamination of a damp, filthy environment. In the wild, reptile have acres of land and water over which their excrement and uneaten food can be scattered. They rarely, if ever, come in contact with this material. This is not the case when reptiles are kept in captivity. Those caring of captive reptiles engage in a continual struggle to prevent bacterial build-up from the inevitable disposition of waste products and uneaten food and to reduce or eliminate, if possible, the animals' direct exposure to these materials.

The best substrate for use in covering cage wire or an aquarium bottom is clean newspaper, or butcher paper. The next best substrate would be indoor-outdoor carpeting. Paper towels squares can also be placed end to end in order to cover the entire bottom of the enclosure. When one of the of the squares becomes soiled, it can be easily removed and replaced without disturbing the entire floor of the enclosure. Under no circumstances should pea gravel, corncob material, wood shavings, sand kitty litter, or sawdust be used. None of these items promote adequate cleanliness and they can be ingested while the iguana is feeding, resulting in intestinal impaction.

It is vital that the environment provided for a captive iguana remain fastidiously clean and dry. Any objects that become soiled with fecal material and/or urinary products should be removed and cleaned or be replaced as soon as possible. It is well advised that the enclosure be set up so that it can be easily cleaned. Human nature dictates that the more time required to clean the cage and the more complicated the task, the less often it will be done. Make the enclosure functional rather than beautiful.

Reptiles are highly susceptible to intoxication from pine oil cleaners such as PineSol and Lysol. These household cleaners should be avoided. We recommend the use of Hibitane (available through our hospital) which is a non-toxic product disinfectant, or a solution made of 1 part bleach to 20 parts of water. The cage should be rinsed after use of this product. All food and waters dishes should be soaked for 30 minutes in this solution to disinfect properly and rinsed thoroughly afterwards.

Visual Security
A place into which a captive iguana can retreat and be free from constant visual scrutiny should be provided. Visual security can be provided by supplying cardboard rolls (from toilet paper or paper towels) for small iguanas or cardboard boxes for large iguanas. Optimum visual security can be provided, however, by strategic placement of artificial plants. Because of the iguana's proclivity for climbing and basking, we suggest that some of the branches and artificial plants provided be arranged in order to allow this activity, above the floor of the enclosure. Silk plants are aesthetically pleasing, easy to clean and maintain and will also withstand the use of chemical sterilants.

Focal heat Source

All reptiles require an increase in the environmental temperature in order to raise their body temperature, and therefore, increase their metabolic rate and activity level. In the wild, basking in the direct sunlight is the usual method by which reptiles achieve this goal.

The optimum environmental temperature during the day should be 85°F to 95°F. This temperature may be allowed to drop to 75°F at night. A thermometer should be present in the cage so that the actual temperature can be known and regulated. The thermometer should be placed at the level or levels where the iguana spends most of its time. Remember, the temperature on the floor of the cage may differ greatly from the temperature near the top. Overall cage heat can be provided with heat tape, or a heating pad under the cage, and/or heating lamp over the cage (out of the physical reach of the reptile). A localized heat source can be provided by a cloth covered "hot rock." The iguana has the option of lying on this object (totally or partially) to receive heat it generates or a boycott it altogether. Care must be taken to assure that this appliance is functioning properly. Malfunctioning hot rocks frequently result in serious thermal injuries.

Sunlight- Artificial Light

Captive reptiles rarely receive adequate exposure to ultraviolet light, especially when they are housed indoors. It is imperative that captive reptiles (especially iguanas) receive direct exposure to sunlight in order to benefit from its ultraviolet component. Ultraviolet (UV) light is necessary in order for an individual to properly absorb and assimilate dietary calcium.

Window glass and plastic filter UV light. Consequently, reptiles must be housed in screen or wire enclosures during the time they are to be exposed to direct sunlight (always provide a shaded area).

An alternative to direct sunlight for indoor-housed reptiles, and during the winter months, is an artificial UV light source. We suggest that you acquire a Vitalite (ask our staff for details). Many so called "plant lights" do not contain UV light, so make sure you use the proper product. In order to approximate a natural photoperiod, it is best to supply 12 to 14 hours of daylight and 10 to 12 hours of darkness each day, with a gradual increase in the number of hours of light supplied in the spring and a gradual decrease in the number of hours provided in the fall and winter months.

Water

Water can be made available to captive iguanas in a variety of ways. A standing water source such as a filled ceramic dish can be available for total body immersion and/or drinking. Spraying water on artificial plants and allowing the iguana to lap up this moisture is another suitable strategy.

The bathtub is a wonderful and practical recreational area for a pet iguana. Swimming is great fun to observe and provides excellent exercise for the iguana. The soaking also stimulates the iguana to empty his intestinal tract and bladder on a regular basis. The tub is also a practical, relatively escape-proof "holding area" for the iguana while its enclosure is being cleaned. The tub should be filled so that its shallowest portion allows for submersion of approximately 2/3 of the iguanas body. Water temperature should be warm and that which would be well tolerated by a human bather. Under no circumstances should an iguana be allowed to swim in a chlorinated pool. br>

Cage Mate

A cage mate for an iguana is not advisable. Iguanas are not particularly sociable animals, but are quite territorial. The addition of a cage mate invites unnecessary aggression and fighting.

Common Disease Problems

Metabolic Bone Disease- Fibrous Osteodystophy
The most common disease problem of captive iguanas results from gross malnutrition and is a widespread problem. Most new iguana owners are not given proper dietary information at the time of acquisition and some are, in fact, given wrong information. The most common mistake made is feeding lettuce (most commonly, iceberg lettuce) to the exclusion of other important dietary items (see section on nutrition). Lettuce provides adequate amounts of moisture, but is a nutritionally barren food otherwise. This dietary indiscretion is often aggravated by Vitamin D3 and calcium deficiencies which results from inadequate exposure to direct sunlight or artificial ultraviolet light and lack of vitamin/mineral supplementation.

Symptoms of fibrous osteodystrophy include general listlessness, an enlarged, swollen lower jaw, difficulty in eating, and markedly firm, swollen limbs and tail. Unfortunately, the overall appearance of the desperately ill iguana is that of a well-fed chubby lizard for which veterinary care is not often sought until it is too late. Sometimes deformity or fractures of the back, tail, or legs are sustained and these problems receive more immediate veterinary attention. The animal may also be suffering from severe, sometimes irreversible kidney disease.

Iguanas suffering from metabolic bone disease should be under the care of competent reptile veterinarian. The prognosis is good if the condition is caught early, but becomes guarded to grave as the disease is more advanced. Therapy will include calcium and vitamin injections along with cage rest (fractures occur easily, so remove all climbing area) and dietary changes with possible initial force feeding.

Iguanas that have become "lettuce junkies" (consume lettuce to the exclusion of other foods) must be encouraged to accept and feed on more nutritionally complete food items. In some cases, these iguanas will accept items that resemble lettuce such as spinach and beet greens and having done so, may be more accepting of other foods offered. Another method of accomplishing this task involves sprinkling the more nutritious items (cut up into small pieces) over the preferred lettuce leaves. In most cases, the iguana will feed on both simultaneously. With each feeding, the proportion of nutritionally superior food items should be increased and the amount of lettuce proportionately decreased until the iguana fully accepts a more nutritious variety of food material. At this time (usually 2 to 3 weeks) a vitamin/mineral powder can be sprinkled over the food items being offered to insure nutritional adequacy. If such a product is used during the transition period, it may cause the iguana to boycott all food, including the lettuce, which would be undesirable.

Another note about diet change: it appears that many iguanas are attracted to red and yellow foods. The use of chopped up flower petals, particularly hibiscus or rose has proven to be very helpful to help expand the diets for many of our patients.

Flaccid Paralysis of Rear Legs
Another disease resulting from malnutrition (vitamin Bl deficiency specifically) has as its major symptom, flaccid paralysis of the rear legs and tail. This problem is treatable with injectable B vitamins and dietary improvement (including vitamin/mineral supplementation). Rear limb paralysis may also result from mineral (especially calcium) deficiencies because fibrous osteodystrophy can afflict the spinal column. Injectable calcium is, therefore, necessary in the therapy of this problem as well.

Rostral Abrasions
One of the unfortunate consequences of captivity is injury to the captive animal resulting from repeated attempts to escape. Iguanas tend to push and rub their noses against the walls of their enclosures as they repeatedly pace back and forth. This constant trauma results in chronic ulceration of the nose (rostrum) whether the walls of the enclosure are made of glass or wire mesh. Rostral injuries may result in serious, even permanent deformities that may have long-term detrimental consequences for the iguana.

Prevention of this problem is difficult but the provision of adequate visual security (hiding places) and other additions to the enclosure will help to minimize it. Furthermore, a visual barrier of dark paint or plastic film placed on or along the lower 8 to 10 centimeters of the enclosures walls often inhibit pacing and rubbing.

Thermal Injuries
Serious burns often result when iguanas are exposed to and inadvertently contact unprotected heat sources within their enclosures. Overhead incandescent light bulbs and heat lamps are most often responsible for these accidents. If these are installed in the cage they should be out of the iguana's reach or outfitted with protective devices to prevent burns. Remember to also check for defective heat rocks.

Blister Disease
Chronic exposure to bacterial contamination from poor sanitation and hygiene is the most common cause of the bacterial infections that afflict captive iguana. Blister disease results when an iguana is confined to a moist, filthy enclosure. The disease is characterized by the formation of blisters, especially on the underside aspects of the iguana's body. These blisters soon develop into seriously infected wounds of the skin. Aggressive antibiotic therapy is necessary to successfully treat afflicted iguanas.

Dry Gangrene of the Tail and/or Toes
Another manifestation of serious, systemic (body-wide) bacterial infection, is dry gangrene of the tail and often, the digits (toes). It is not uncommon for the dry gangrene to very slowly ascend the tail from its tip and for one or more toes to exhibit the same type of progressive problem simultaneously. That tissue which is involved is, of course, not salvageable, but affected iguanas can be spared further advancement of the disease process by aggressive antibiotic therapy and prompt initiation of strict hygiene and optimum husbandry.

Mouth Rot
Generalized bacterial infection of the mouth is often the result of malnutrition and a debilitated, weakened condition. Symptoms of mouth rot include swelling and inflammation and accumulations of pus within the mouth, increased salivation, and difficulties in feeding. Treatment involves identification of the offending bacteria, usually through a culture and sensitivity of the material in the mouth, and institution of appropriate antibiotic therapy. Supportive care (administration of vitamins, fluid therapy, force feeding if necessary, .etc.) is also essential for the successful outcome of these cases.

Abcesses
Bacterial infections may localize in one or more areas (externally or internally) sometimes resulting in abscess formation. Reptile pus is not liquid and possesses a cheesy, sometimes rubber-like consistency. Consequently, treatment of abscesses by a veterinarian involves opening up the pus cavity and manually cleaning it out. Antibiotics are then used - directly into the defect and are usually used by injection as well.

Bacterial diseases of reptiles require aggressive therapy (injectable antibiotics) to insure that the causative germs are eliminated from the body as rapidly and completely as possible. When therapy is delayed or insufficient, bacteria are allowed to proliferate unchecked throughout the body, resulting internal abscesses. Antibiotic therapy at this point is much more difficult and much less successful. An initial and periodic white blood cell count is necessary in order to properly evaluate and monitor the progress of the patient and to insure that a relapse does not occur.

Parasite Problems
Parasites may be found externally (mites), within the gastrointestinal tract (worms, protozoa), and within the blood stream (malaria-type parasites) of captive iguanas. Parasites represent a significant burden in addition to the inevitable stresses of captivity endured by all pet iguanas, and should be treated by a veterinarian specializing in reptiles. Iguanas weakened by malnutrition and chronic bacterial infections are 'particularly susceptible' to the detrimental effects of parasites.

Organ Failure
Failure of vital organs often accompanies advancing age, but may also be a consequence of certain metabolic diseases (i.e. gout) and severe, unchecked bacterial infections. Blood samples of a sufficient volume to allow evaluation of vital organ integrity must be collected on these patients if at all possible. Treatment by a veterinarian is usually symptomatic and dictated by appropriate diagnostic testing.

Bladder Stones
Stones (accumulations of minerals that precipitate out of the urine) may form within the urinary bladder of iguanas. The affected animal may exhibit no symptoms at all or may strain during urination and act listless. If the stone reaches very large proportions, abdominal enlargement may be noted as well. Sometimes blood is noted in the droppings of an affected iguana. An X-ray is necessary to confirm the diagnosis and abdominal surgery is necessary to remove the stone.

Egg-binding
Egg-binding can be a life-threatening condition. It results when a gravid female is unable to expel one or more of the eggs residing within her reproductive tract, in spite of diligent efforts on her part to do so. Causes of egg-binding are many and varied including malnutrition (mineral imbalances especially), concurrent disease, mummification of one or more eggs, and large or malformed eggs. Physical examination and X-rays are necessary in order to diagnose this problem. A veterinarian might elect a medical and/or surgical approach to relieve this serious condition, depending upon the individual circumstance.

*Please note that a female iguana does not need any exposure to a male to produce eggs.

Broken tail
Although iguanas do not shed their tail like some lizard species, fractures, dislocations, and other serious injuries to this relatively vulnerable part of their anatomy do occur. Care must be taken to firmly restrain the tail when an iguana is picked up and held. A veterinarian can treat soft tissue injuries according to their severity and can "set" and splint the tail if necessary.

Broken Toes
An iguana's toes are even more vulnerable, especially when iguanas are housed within screened or wired enclosures. It is very easy for toes and/or toenails to become entrapped within the wire mesh of these fabrics, resulting in fractures, dislocations, torn nails (with subsequent bleeding), and injuries to the skin and scales of the toes. These injuries are most likely to occur when attempts are made to remove a panicked iguana from its enclosure. Great care should be taken when removal of an iguana involves overcoming its grip onto the wire mesh of its enclosure. Twisting of the iguana's body against this steadfast grip often results in serious injuries to the feet and toes. A veterinarian should be consulted at once if such injuries are incurred.

Conclusion

We strongly recommend that all newly acquired iguanas (regardless of age) be thoroughly examined as soon after acquisition as possible. Besides a complete physical examination, blood work-up and fecal (stool) examination should be included. The advantage of this thorough post-acquisition work-up is that current medical problems, as well as potential problems, can be identified and treated before they create serious problems for the individual. A thorough post-acquisition work-up, therefore, becomes the cornerstone of a preventative health care program for the pet iguana.