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Island Exotic Veterinary Care
Huntington, New York
The majority of problems seen in pet reptiles are a result of improper caging, feeding, and lighting techniques. The green iguana (Iguana iguana) is one of the most popular reptile species kept as a pet and unfortunately, one of the least understood. Here are some brief suggestions for captive management.
The green iguana is an arboreal (tree-living), diurnal (active in daytime), foliovore (leaf-eater) naturally found in Mexico, Central and South America. The iguana is a basking lizard that thrives in daytime temperatures near 100ºF. They are strict herbivores from hatching through adulthood and do not eat insects or mice at any time during their development (as previously thought).
In captivity, iguanas grow rapidly (10 - 25 inches/yr.) and reach adult size in 2-3 years if properly cared for. They will need large tanks or enclosures to accommodate this growth. Like all reptiles, iguanas are solitary species and should be housed as individuals. Dominance and aggression can result in severe injuries or poor growth for the subordinate lizard. Lizards should not be allowed to roam free in the house because they will not receive adequate heat, or UV light, and they are prone to ingesting foreign matter (hair, coins, e.g.).
Substrate (cage floor covering) comes in a variety of materials. An ideal substrate should be inexpensive, easy to clean, digestible if eaten, and pleasant to look at. Newspaper works well, but indoor/outdoor carpeting (Astroturf) is more aesthetic and is easy to clean and disinfect. Alfalfa pellets (rabbit food) can be used. Avoid the use of sand, corncob, gravel, shavings, and small wood chips. These can be eaten by the iguana resulting in mouth abrasions and gastrointestinal impactions. They are also difficult to keep clean and can harbor bacteria and fungal organisms.
Lighting is very important to basking lizards like the iguana. The full spectrum of natural light provided by the sun plays an integral role in vitamin synthesis and calcium metabolism. Both UVA and UVB wavelengths are recommended. UVB (wavelength 290-320 nm) is necessary for vitamin D activation in the skin. Unfiltered sunlight (not through glass or plastic) is always the best source of ultraviolet radiation and when outside temperatures are above 70oF, the iguana should be exposed to direct sunlight. Indoor UV lighting is important in the colder months. Black light (BL type) fluorescent bulbs (General Electric Co.), Vita-lite® fluorescent tubes (Durotest, Lyndhurst, NJ), Reptisun or IguanaSun 5.0 (Zoomed Co.), and Chromalux bulbs (Valentine Equipment Co., Chicago) are good choices. Plant grow lights or black light blue (BLB) tubes for psychedelic posters do not work. The UV lights must be placed no more than 24 inches away from the lizard and should be left on 10-12 hours per day and turned off at night. These bulbs lose their UV radiation in time (even though they continue to give off light) and should be replaced every year.
Supplemental Heat is needed for captive iguanas. Iguanas must be in their preferred optimal temperature zone (POTZ) for metabolic processes like digestion, growth, healing, and immune system function. Temperature ranges during the day should be 85-95ºF and not less than 75ºF at night. A temperature gradient within the enclosure is recommended, with a focal hot spot or basking area of 95-100ºF. An incandescent or infrared bulb placed outside of the cage works well. Be careful not to burn the iguana; it should not be able to get too close to the heat source. Use thermometers to measure the temperature both on the substrate as well as on top of any climbing branches within the enclosure. Hot rocks do not work and are not recommended. Iguanas also need humidity; do not let the tank get too dry (or too damp). Daily light misting with a water spray bottle can help raise humidity.
Green iguanas are strict herbivores and in the wild, eat a diet of leaves and vines. Captive iguanas should be fed a diet consisting of 80% vegetables and 20% fruit chopped into small pieces and mixed together. High protein supplements like dog, cat or monkey chow can lead to kidney problems and should not be given, even to juveniles. Dark leafy greens high in calcium and low in phosphorus should make up the majority of the diet and include collard greens, mustard, dandelion, Swiss chard, escarole, spinach, parsley, and watercress. Apples, grapes, melons, papaya, kiwi, and strawberries can be fed in small amounts. Bananas and iceberg lettuce are not recommended. The key to success is a wide variety of foods. Juveniles less than 1 year of age can be fed daily, adults can skip meals one or two days a week. Be careful with commercially prepared diets; not all of these have been properly tested and a single product should not be relied on as the sole diet. Water bowls large and heavy enough for the iguana to climb into should be provided.
Vitamins and Minerals can be added to the diets of iguanas. Care must be taken not to overdose supplements, especially those containing phosphorus and vitamin D. Use vitamins sparingly (once or twice weekly). Calcium can be supplemented in the form of powdered calcium carbonate lactate, or gluconate; cuttlebone shavings work well. Sprinkle calcium lightly on food 2-3 times weekly. Do not use a calcium product that contains vitamin D or phosphorus (read labels!).
Recently, iguanas have been reported as an increasingly frequent cause of Salmonella transmission to people. According to the Center for Disease Control reptiles accounted for an estimated 2-5% of the over one million cases in 1993. That is at least 20,000 cases, which is a cause for concern. Please see my website article "Salmonella and Pet Reptiles" for more info.
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