Green Iguana Care
Dr. Jenni Bass
The green iguana (Iguana iguana) is one of the most popular reptiles in the pet trade. It is also one of the most difficult to keep successfully. Prior to the purchase of an iguana, the cage, or the cage accessories, one should make every effort to learn about these lizards and their very specific needs. As a reptile owner, you will be responsible for creating a micro-environment that will mimic the animal's natural environment.
Reptiles are dependent on their environment to provide them with a choice of temperatures within a range specific to each species of reptile. This range is referred to as the preferred optimal temperature zone (POTZ). A reptile will fail to thrive if kept at only one temperature within this range. Similarly, a lighting gradient should be provided; there must be areas of shade or filtered light, as well as an area of bright light in which to bask.
Ultraviolet (UV) light, specifically UVB rays, 280 to 315 nm, are essential to the health of the iguana. When UV rays contact the skin, they cause the conversion of vitamin D into a form that is necessary for the absorption and metabolism of calcium. Disturbances of calcium metabolism result in broken bones, osteoporosis, growth abnormalities, egg binding, tremors, seizures, paralysis and death. These and other signs related to calcium, temperature and lighting problems are among the most common reasons iguanas are presented to reptile veterinarians.
Iguanas require diets high in calcium and fiber. However, without the provision of appropriate temperatures, an iguana will not digest its food properly, its immune system will not function as it should and as a result, the lizard will not grow normally and will be more susceptible to disease. Failure to meet the basic physical and psychological needs of the iguana, including the need for visual security and privacy, will cause stress. Stress leads to a weakened immune system, increased susceptibility to infection, a poor appetite, and failure to thrive.
Iguanas are solitary, territorial creatures. Mature animals do not form recognizable social or group structures. Except during the breeding season, they spend little time together, and females do not provide care for their young. As hatchlings, before hormones have their influence, iguanas group for safety from predators. However, once they reach four to six months of age iguanas should be housed individually as they become territorial.
Aggression among animals often leads to serious, even fatal injuries. Aggressive displays by iguanas are very subtle, and owners may fail to notice signs of impending overt aggression among lizards. Some individuals are dominant, , particularly among the males, and even though they may not physically attack subordinate cage mates, subtle threats, or displays that take place when the owner is not watching are a source of considerable stress for animals that naturally live alone. It is not unusual for a dominant animal to keep cage mates from the food bowl and from the best basking spots. If iguanas must be housed together, plenty of space, visual barriers, multiple basking spots, feeding stations, and water sources are necessary.
Young iguanas should be handled only for a few minutes daily, as anything more than this is stressful. Being out of the cage for any length of time will result in the body temperature dropping and a cool iguana will not thrive. When alarmed or threatened, iguanas, particularly young iguanas, will jump erratically. In a wild situation, they leap from branch to branch and away from danger. In captivity the result may be an unpredictable leap from a shoulder. Be prepared for these sudden leaps and handle the animal securely and close to the ground, as serious injuries can occur.
Resist grabbing the tail of the iguana, as it can easily detach. This is another escape mechanism. More mature animals tend to whip their powerful tails or perform a 360 degree roll in an effort to escape. The sandpaper-like skin of larger animals can make this a painful experience for the handler and gloves and long sleeves may be necessary when handling even a calm animal. Although some individuals do bite, iguanas are not usually an aggressive species towards humans, and such behaviors are usually just an indication of a wish to escape. Some individuals, especially mature males, can become aggressive, even though they have been handled gently all their lives. This may be seasonal and related to hormones, and may be difficult to manage.
Since iguanas are by nature territorial, lizards that have free run of the house can be particularly prone to development of defensive or aggressive behaviors. A sudden change in behavior, whether increased docility or aggression warrants a visit to your reptile veterinarian, as it may signal that the animal is in pain or is ill. There are no simple solutions to dealing with a six foot, aggressive male iguana, but a discussion with your reptile veterinarian is the place to start.
Iguanas in the wild spend a great deal of time basking in the sun, particularly after eating, as the heat of the sun helps them to digest their food. At the same time the animal is absorbing beneficial ultraviolet rays, which are vital to calcium metabolism. This is why in captivity your iguana is attracted to bright light rather than to heat. In the wild finding a nice sunny spot provides him heat as well as ultraviolet light. In captivity, therefore, an iguana's basking "hot spot" should also be the focus of the ultraviolet light.
Iguanas are prey animals in the wild, and so should be housed in relatively quiet areas with good visual security. They are susceptible to the effects of noise and vibration and will not enjoy being stared at by "predators" such as dogs and cats. For these reasons it is best to house iguanas in little used, quiet rooms.
Iguanas that rub their noses on cage walls or dig incessantly are showing signs of stress. Stress can come in the form of excessive handling, improper housing or diet as well as inappropriate temperature, humidity and lighting conditions. You should reassess husbandry conditions and diet periodically. Be familiar with the normal appearance and behavior of the species. Pay regular visits to a veterinarian who is familiar with reptiles, and educate yourself as to the natural history and husbandry requirements of the iguana.