Green Iguana

Is a green iguana right for you?

In a pet shop the green iguana (Iguana iguana) looks like a cute, palm-sized lizard. Within a few years, however, it reaches 1.2-1.7 metres including the tail, with some males reaching 1.8 metres or more. VCA notes that adults can weigh 7-9 kg. It has a powerful tail whip, sharp claws and teeth. It is frequently given up once it grows. This species suits only experienced keepers who can dedicate a room to it.

Ask yourself honestly before deciding: where will you keep this animal when it is nearly two metres long?

Before you adopt

Legal status: The green iguana is listed in CITES Appendix II, so international trade requires CITES permits (in Turkey, for example, these are issued by the General Directorate of Nature Conservation and National Parks). Check your local rules and ask for paperwork showing the animal came through legal channels.

Consider rehoming first. Iguanas given up after they grow are common in rehoming listings and reptile groups. Taking on an adult lets you see its real size and temperament from the start.

Never release one. In places such as Florida, Puerto Rico and Hawaii, released or escaped iguanas have formed invasive populations. In a temperate winter it would not survive.

A healthy animal has bright eyes, a well-filled body and a straight jaw and legs. If you see a soft or swollen jaw, tremors, wrinkled skin, a sore on the nose or a darkened tail, do not take that animal.

Vivarium set-up

Size

• Juvenile: temporarily about 120x60x120 cm.
• Adult: ReptiFiles' minimum is 3 m long x 1.5 m deep x 1.8 m high. In practice that means a custom-built enclosure or a safe, iguana-proofed room.
• It lives in trees; it needs both horizontal space to move around and thick, sloping branches leading up to the basking spot.

The heat gradient

These are VCA's ranges; ReptiFiles recommends a basking surface of around 50 °C. Heat sources and lamps must be guarded so the iguana cannot touch them, otherwise serious burns can occur. Do not use heat rocks. A thermostat and a probe thermometer are essential. Without enough heat, digestion stops.

Humidity The Merck Veterinary Manual gives 60-85%, and ReptiFiles 60-80% by day. In centrally heated rooms in winter humidity drops fast; monitor with a hygrometer and add daily misting and a large water bowl.

UVB (non-negotiable)

• 10-12 hours a day, off at night.
• Fluorescent UVB tubes should be no more than 30 cm from where the animal sits (VCA). With strong T5 HO tubes, ReptiFiles targets a UV index of 3-4 at the basking spot.
• Glass and acrylic block UVB.
• Replace the tube every 6 months (or as the manufacturer advises).
• When it is above 27 °C outside, supervised natural sunlight in an escape-proof cage is very valuable, as long as shade and water are provided.

Substrate Newspaper, paper, recycled paper pellets or reptile carpet. Sand, gravel, wood shavings, corncob, walnut shell and cat litter are not recommended because they may be swallowed.

A laying box for females Female iguanas produce eggs even without a male. Give a sexually mature female a digging box filled with at least 30-60 cm of moist soil.

Feeding

The green iguana is herbivorous. The most common mistake is feeding it insects or cat and dog food.

Diet ratio

• 80-90% dark leafy greens and other vegetables
• Fruit less than 10-20% of the total

Animal protein: The Chicago Exotics veterinary clinic advises none at all; VCA tolerates less than 5% in adults. Never give cat or dog food.

Calcium-rich staple greens: collard greens, mustard greens, turnip greens, dandelion, parsley, bok choy, alfalfa hay.

Other vegetables: squash, courgette, sweet pepper, green beans, grated carrot, okra, sweet potato.

Limited: spinach, chard, beet greens (they block calcium absorption); cabbage and other brassicas (in excess they can cause goitre; rotate them).

Do not give: iceberg lettuce and celery (very low nutritional value), avocado, cat and dog food.

Supplements (VCA)

• Growing iguanas: calcium powder 4-5 times a week, a multivitamin with vitamin D twice a week
• Adults: calcium 1-2 times a week, a multivitamin with vitamin D twice a month

Water: Merck stresses that inadequate water intake predisposes green iguanas to kidney disease. Provide a large water bowl, regular misting and lukewarm baths. Juveniles are fed daily, adults daily or every other day.

Health and lifespan

Lifespan is usually 15-20 years; Chicago Exotics gives an average of 10-16 years and reports individuals reaching 25.

Signs that mean a vet visit:

• A soft, swollen jaw; swollen or bent legs, tremors
• Appetite loss, weight loss, a listless posture
• Signs of dehydration: wrinkled skin, sunken eyes, yellowed or absent urates
• In females: a swollen belly, digging without laying, weakness
• Burns, a sore on the nose, darkening of tail or toe tips

Problems common in the species:

• Metabolic bone disease: Not enough UVB, heat or calcium. Soft jaw, tremors, fractures. One of the most common problems in captive iguanas.
• Kidney disease: Merck points to chronic dehydration as a predisposing cause; excess protein is another risk to avoid. Signs appear late; by the time appetite loss and weakness are noticed, the disease may be advanced.
• Egg binding and follicular stasis: Also seen in females kept without a male. A few weeks of reduced appetite before laying can be normal, but weakness, dull colour, weight loss or a swollen vent mean an immediate vet visit.
• Burns: From unguarded lamps and heat rocks.
• Parasites: An annual faecal check is recommended.

Salmonella: Green iguanas can naturally carry Salmonella in their gut. The CDC advises that children under 5 should not handle reptiles; adults over 65 and people with weakened immunity are also at higher risk. Wash your hands after every contact; never let the iguana roam in the kitchen or bathe or clean it in the kitchen sink or food preparation areas. If you use the bathtub, disinfect it afterwards.

Handling and behaviour

1. Handle juveniles briefly and calmly every day. According to Chicago Exotics, young iguanas can become calm with regular handling.
2. Support the body and hips together. Never hold it by the tail; in juveniles the tail can break off, and the regrown tail looks different.
3. Learn the warning signs: extending the dewlap and head bobbing signal territorial defence; do not force contact at that moment.
4. Never underestimate an adult's strength. Tail whips, claws and bites can cause serious injuries; wear long sleeves.

Breeding season: Males reaching sexual maturity (usually at 2-4 years) can become seasonally aggressive even after years of being placid. Reduce handling during this period and respect the animal's territory.

Never keep two males together. The dominant animal will drive the other away from basking and feeding areas.

History and life in the wild

The green iguana ranges from southern Mexico to central Brazil, Paraguay and Bolivia and across the Caribbean, living and basking in trees. On top of its head is a primitive structure called the "parietal eye" that detects changes in light.

In the wild it eats leaves, flowers and fruit. Females lay 20-71 eggs once a year. It is extremely common in the pet trade, but its adult size and care needs are often overlooked at the time of purchase. Released iguanas have become invasive in Florida, Puerto Rico, Hawaii and Taiwan.