Table of Contents:
Natural History
Requirements in Captivity Diet
Intestinal Inoculation
Hygiene
Visual Security
Focal Heat Source
Sunlight and Artificial Light
Water
Cage Mate
A Comment Regarding Sharp Claws
Veterinary Examination
Metabolic Bone Disease (Fibrous Osteodystrophy)
Paralysis Of The Rear Legs
Nose Abrasions
Thermal Injuries
Bacterial Infections
Natural History
The green (or common) iguana (Iguana iguana) is an arboreal (tree-living) and diurnal (daylight-active) lizard usually found at elevations below 3000 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 have short, powerful limbs equipped with strong, sharp claws (for climbing and digging), and a long, strong tail. They can reach lengths of 6 to 61 feet. A large flap of skin (the dewlap) hangs from the throat and helps regulate body temperature. Iguanas also have a prominent crest of soft spines (longer in males) along the midline of the neck and back, beginning at the base of the skull.
Male iguanas tend to be larger and have brighter overall coloration than females. The distinct color of males is especially pronounced during the breeding season. Males tend to have larger heads than females, in part because of swollen jowls. Both sexes have 12-13 prominent pores arranged in a row on the underside of both thighs. These glandular structures secrete a waxy substance with which iguanas mark their territory and identify each other. As the males mature their "femoral pores" develop slight outward projection. This developmental modification probably enables the male to better grasp the female during copulation.
An iguana's 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 blue-green with dark-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 tree branches, often over water. When frightened or threatened, they 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. Iguanas can also safely land on the ground and run to protective cover after jumping from substantial heights. When threatened or cornered, iguanas can defend themselves with astonishingly quick, whip-like lashes of their tails and with their claws and jaws.
Iguanas mate November through February, depending upon the region. After a pregnancy of about 2 months, the female digs in moist sand or soil, usually near the base of a tree, and deposits 25-45 eggs. The hatchlings, measuring 25-30 centimeters long, emerge in about 2 weeks. They grow 15-24 centimeters a year and attain sexual maturity in about 3 years.
An interesting, but unfortunate, fact is that the iguana is widely hunted throughout its range for its tender white flesh and for its alleged aphrodisiac properties. Central American natives refer to the green iguana as "bamboo chicken." Because it is timid and relatively slow, it is easily captured. Its eggs are also collected and eaten by local hunters.
Requirements In Captivity Diet
In its natural environment, the green iguana is almost completely herbivorous (plant-eating) from the time it hatches. Despite this, captive juvenile iguanas should be fed some animal protein. Older iguanas should receive a greater proportion of vegetable matter in their diets.
Juvenile iguanas should be fed daily. A good diet consists of 1 part animal protein (water-packed tuna, cooked chicken, hard-boiled or scrambled egg, Purina Trout Chow™, dog food) added to 2 parts vegetable material (broccoli and its leaves, Swiss chard, spinach, alfalfa sprouts, beet, collard, mustard and turnip greens, carrots tops and thawed, frozen mixed vegetables). Chop all of the ingredients into a size that can be easily handled by the young iguana. Then mix them thoroughly and store the mixture in the refrigerator in an air-tight container. Once or twice a day, offer a small amount of this mixture after it has been liberally sprinkled with an appropriate vitamin-mineral supplement.
Particular attention to calcium supplementation is essential because young, growing iguanas are very prone to calcium deficiencies. Growing iguanas may also be fed "expanded" guinea pig or rabbit pellets (pellets allowed to expand by absorbing water), either plain or as a top dressing over vegetables. This is a convenient way to add necessary vitamins and minerals (contained in the pelleted food) to the iguana's diet.
An alternative method of vitamin-mineral supplementation works well in all but very small iguanas. Empty gelatin capsules can be filled with vitamin-mineral supplement. The filled capsule is then inserted directly into the iguana's mouth using a pilling device originally designed for use in cats. This direct method of supplementation ensures that the iguana receives its required supplement, and also eliminates the waste associated with sprinkling the supplement on food.
Older iguanas can be fed daily or 2-3 times per week, and can be offered the same items as listed above. Plant material, such as dandelions (flowers and leaves), clover, rose petals, and flowers of hibiscus, carnation and nasturtium should be offered. Many health food stores carry dried dandelion and other edible herbs that can be offered to captive iguanas all year round. Fresh fruit (bananas, berries, apples, peaches, pears, plums) can occasionally be included in the diet.
Intestinal Inoculation
A fairly recent discovery has provided a probable explanation for the premature deaths of young iguanas despite apparently adequate diets. In the wild, young iguanas obtain needed intestinal bacteria and protozoa by eating the feces of adult iguanas. The microorganisms acquired this way are essential for digestion of plant material. Baby iguanas are not born with these microbes, so young iguanas reared in captivity never acquire them.
All newly acquired, domestically raised (not wild caught) iguanas should receive fresh feces from a healthy, parasite-free adult iguana (preferably wild caught). One dose should inoculate the iguana for life. Some veterinary hospitals are prepared to assist new iguana owners with this procedure.
Hygiene
Next to adequate nutrition, no other aspect of husbandry for captive reptiles is more important than sanitation and hygiene. Many bacterial and fungal diseases of captive reptiles result from their daily exposure to fecal contamination and a damp, filthy environment. In the wild, reptiles have acres of land and water over which their feces and uneaten food can be scattered. They rarely, if ever, come in contact with this material. This is not the case with captive reptiles. Owners of captive reptiles engage in a continual struggle to prevent bacterial buildup caused by inevitable deposition of waste products and uneaten food.
An iguana's cage floor or aquarium bottom can be covered with clean newspaper (unprinted preferably) or butcher paper. The next best material is indoor-outdoor carpeting. Paper towel squares can also be placed end to end to cover the entire bottom of the enclosure. When one of the squares becomes soiled, it can be easily removed , and replace 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 promotes adequate cleanliness, and they may be eaten while the iguana is feeding, resulting in intestinal impaction. Iguanas are frequently displayed on moss. Even though this is visually attractive, it is a poor husbandry practice because this material remains continually damp, promoting serious skin infection.
A captive iguana's environment must be kept fastidiously clean and dry. Any object that becomes soiled with feces or urine should be removed and cleaned or replaced as soon as possible. The enclosure should be set up so that it can be easily cleaned. Human nature dictates that the more complicated the task, the less often it will be done. Make the enclosure functional rather than beautiful.
Reptiles are highly susceptible to poisoning from pine oil cleaners, such as PineSol™ and Lysol™. These household cleaners must be avoided. Generally, cages should be cleaned with a gentle soap and water and rinsed. Then, using household bleach in a 30 parts water to 1 part bleach the enclosure can be disinfected. Alternately, sun-drying the cleaned cage can also help kill bacteria.
Visual Security
A hiding 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. Optimal visual security can be provided, however, by strategic placement of artificial plants. Because iguanas like to climb and bask, some of the branches and artificial plants provided should be arranged to allow this activity above the floor of the enclosure. Silk artificial plants are visually pleasing and easy to clean and maintain, and also withstand the use of disinfectants.
Focal Heat Source
All reptiles require a warm environmental temperature to raise their body temperature and increase their metabolic rate and activity level. The optimal environmental temperature to provide for captive iguanas in their enclosures is between 85 ° F and 103°F.
Wild reptiles bask in direct sunlight. Captive iguanas do quite well when a "hot rock" is provided. The iguana has the option of lying on it (totally or partially) to obtain heat as needed. A heating pad may be provided for larger iguanas. Care must be taken to ensure the appliance is functioning properly. Malfunctioning hot rocks and heating pads can cause serious burns.
Sunlight and Artificial Light
Captive reptiles rarely receive adequate exposure to ultraviolet (UV) light, especially when they are housed indoors. Captive reptiles, especially iguanas, must receive direct sunlight to benefit from its UV component. Ultraviolet light is necessary to properly absorb dietary calcium. Window glass and plastics filter UV light. Consequently, reptiles must be house in screened or wire enclosures during the time they are to be exposed to direct sunlight. Also, a shaded area must be provided so the iguana can avoid heat stroke from overexposure to sunlight. An alternative to direct sunlight for reptiles housed indoors is an artificial UV light source, such as a Vitalite™. When an artificial source of ultraviolet light is provided, do not place any glass or plastic partition between the light source and the iguana.
To approximate a natural photoperiod, it is best to supply 10-12 hours of daylight and 12-14 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 bathing and 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 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 about 2/3 of the iguana's body. The water should be warm and of a temperature comfortable for a human bather. Iguanas may be allowed to occasionally swim in chlorinated swimming pools as long as the activity is closely supervised and the iguana is thoroughly rinsed of with fresh water afterward.
Cage Mate
A cage mate for an iguana is not advisable. Iguanas are not particularly sociable animals and are quite territorial. The addition of a cage mate invites unnecessary aggression and fighting.
DISEASES REQUIRING VETERINARY ATTENTION
Metabolic Bone Disease (Fibrous Osteodystrophy)
The most common disease of captive iguanas results from gross malnutrition. Most new iguana owners are not given proper dietary counseling when they buy their iguana. In fact, many are given incorrect information The most common mistake is feeding lettuce (usually iceberg lettuce) to the exclusion of other important dietary items (see the section on Diet). Lettuce provides adequate amounts of moisture but is a nutritionally barren food otherwise. The problem is often aggravated by vitamin D3 and calcium deficiencies, which result from inadequate exposure to direct sunlight or artificial ultraviolet light and lack of vitamin-mineral supplementation.
Signs of fibrous osteodystrophy include general listlessness, and enlarged, swollen lower jaw, difficulty in eating, and markedly firm, swollen limbs and tail. Unfortunately, these desperately ill iguanas appear well-fed and chubby, and veterinary care is not often sought until it is too late. Sometimes the back, tail or legs are fractured or deformed. These problems usually receive more immediate veterinary attention.
Iguanas with metabolic bone disease should be treated by a competent reptile veterinarian. If the patient refuses all food offered except lettuce, the lettuce must be top dressed with a suitable vitamin-mineral powder. Iguanas of sufficient size may be given the supplement directly in filled gelatin capsules, as described above. 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. Some iguanas accept items that resemble lettuce, such as spinach and beet greens, and then may be more accepting of other foods offered. Another way to wean an iguana from lettuce involves sprinkling the more nutritious items (cut up in small pieces) over the preferred lettuce leaves. Usually 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 decreased until the iguana has fully accepted a more nutritious variety of food. After 2-3 weeks, a vitamin-mineral powder can be sprinkled over the food to ensure nutritional adequacy. If such a product is used during the transition period, it may cause the iguana to refuse all food, including the lettuce. This would be undesirable.
Paralysis Of The Rear Legs
A disease resulting from vitamin B' deficiency causes paralysis of the rear legs and tail. This problem is treated with injectable B vitamins and dietary improvement, including vitamin-mineral supplementation. Rear limb paralysis may also result from mineral (especially calcium) deficiencies that cause fibrous osteodystrophy of the spinal column. Injectable calcium is also necessary in the therapy of this problem.
Nose Abrasions
One of the unfortunate consequences of captivity is injury resulting from repeated attempts to escape. Iguanas tend to push and rub their noses against the wall 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. Nose injuries may result in serious and often permanent deformities that may cause long-term problems.
Preventing this problem is difficult, but providing adequate visual security (biding places) and other additions to the enclosure (artificial plants, branches, rocks) helps to minimize it. A visual barrier of dark paint or plastic film placed on or along the lower 4 inches of the enclosure's walls often inhibits pacing and rubbing.
Thermal Injuries
Serious burns often result when iguanas contact unprotected heat sources within their enclosures. Exposed light bulbs and heat lamps are most often responsible for these accidents. Neither of these appliances is actually necessary. If they are installed in an iguana's enclosure, they must be outfitted with a protective device to prevent burns.
Bacterial Infections
Blister Disease: Chronic exposure to bacterial contamination from poor sanitation and hygiene is the most common cause of bacterial infections in captive iguanas. Blister disease results when an iguana is confined to a moist, filthy enclosure. The disease is characterized by blisters, especially on the underside aspects of the body, that develop into seriously infected wounds. Aggressive antibiotic therapy is necessary to successfully treat affected iguanas.
Dry Gangrene of Tail or Toes: Another sign of serious, body-wide bacterial infection is dry gangrene of the tail and often the toes. The dry gangrene usually slowly moves up the tail from its tip. One or more toes may have the same type of progressive problem simultaneously. The disease can be controlled with aggressive antibiotic therapy, strict hygiene and good husbandry. A suddenly frightened iguana may whip its tail back and forth, injuring the tip against the walls of the enclosure. Such an injury may lead to dry gangrene of the tail.
Mouth Rot: Bacterial infection of the mouth is often the result of malnutrition and a debilitated, weakened condition. Signs of mouth rot include swelling, inflammation and accumulation of pus within the mouth, increased salivation, and difficulties in eating. Treatment involves identifying the offending bacteria and giving appropriate antibiotic therapy. Providing vitamins, fluids and forced feeding are also essential.
Abscesses: Bacterial infection may settle in 1 or more areas and result in abscess formation. Reptile pus is not liquid, but is of a cheesy, sometimes rubber-like consistency. Consequently, treatment of abscesses by a veterinarian involves opening up the pus-filled abscess and manually cleaning it out. Antibiotics are then infused directly into the cavity and also given by injection.
Bacterial infections of reptiles require injectable antibiotics to eliminate the bacteria from the body as rapidly as possible. When therapy is delayed or insufficient, bacteria multiply and spread throughout the body, usually resulting in internal abscesses. Antibiotic therapy then is much less successful. Initial and periodic white blood cell counts are necessary to properly monitor the progress of the patient and to detect any relapse.
Parasite Problems: Parasites may bc found externally (mites), within the gastrointestinal tract (worms' protozoa), and within the blood (malaria-type parasites) of captive iguanas. Parasites represent a significant burden in addition to the 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.
Viral Infections: Though viruses probably cause disease in iguanas, only a few have been specifically identified in this capacity. With continued interest and research in iguanas, our understanding of viral infections will be enhanced.
Organ Failure: Failure of vital organs often accompanies advancing age, and may also be a consequence of gout and severe bacterial infections. If possible, blood samples should be collected to allow evaluation of vital organ function. Treatment by a veterinarian is usually dictated by the results of diagnostic testing.
Bladder Stones: Minerals in the urine may precipitate and form stones within the urinary bladder of iguanas. The iguana may exhibit no signs of illness or may strain during urination and act listless. If the stone becomes very large, the abdomen may become enlarged. Droppings may contain blood. A radiograph (x-ray) is necessary to confirm the diagnosis. Abdominal surgery is necessary to remove the stone.
Egg-Binding: Egg-binding can be a life-threatening condition. It results when a pregnant female cannot expel 1 or more eggs from the reproductive tract. Causes of egg-binding include malnutrition (especially mineral imbalances), various diseases, mummification of eggs, and large or malformed eggs. Physical examination and radiographs (x-ray) are necessary to diagnose this problem. The veterinarian may select a medical and/or surgical approach to relieve this serious condition, depending upon circumstances.
Swollen Jaw: See Fibrous Osteodystrophy.
Broken Tail: Though iguanas do not easily shed their tails like some other lizard species, tail fractures, dislocations and other serious injuries may 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 fractured tail if necessary.
Broken Toes: An iguana's toes are very vulnerable to injury, especially when iguanas are housed in screened or wire enclosures. It is very easy for toes and/or claws to become entrapped within the wire mesh, resulting in fractures, dislocations, torn claws (with subsequent bleeding), and injuries to the skin and scales of the toes. These injuries often occur during attempts to remove a panicked iguana from its enclosure. Great care should be taken when overcoming the animal's grip on the wire mesh. Twisting of the iguana's body against this steadfast grip often causes serious injuries to the feet and toes. A veterinarian should be consulted at once if such injuries occur.
A Comment Regarding Sharp Claws
Iguanas are usually quite docile and enjoy handling. You, however, may not always enjoy the activity because of the scratches inflicted by sharp claws, powered by very strong limbs. An iguana's claws should be periodically dulled by an experienced veterinarian or veterinary technician. A cautery instrument or high-speed grinding tool is usually employed for this task.
VETERINARY EXAMINATION
A thorough initial examination is the cornerstone of a health care program for the pet iguana. All newly acquired iguanas regardless of age, should be thoroughly examined by a veterinarian as soon as possible. Besides a complete physical examination, a blood workup and stool examination should be included. The advantage of this thorough initial workup is that current and potential medical problems can be identified and treated before they become serious.
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