iguanas (Iguana iguana) are large semi-arboreal to arboreal lizards
of the primarily New World Americas. They are almost an exclusively herbivorous
reptile. Earlier beliefs were that the juveniles were insectivores, and
then gradually grew into herbivorous adults. However recent studies on
stomach content in wild iguanas have revealed that this is not the case.
Iguanas are born herbivores and do not go through an ontogenetic shift
from insectivore to herbivore. The digestive system is therefore designed
plant materials and not, as some recommend, to digest meat in any amount.
The green iguana has evolved an elaborate hindgut, housing a microbial
fermentation system that allows it to utilize fiber as effectively as mammalian
ruminants. The adult iguanas spend most of their time in the upper parts
of the trees, while the juveniles are either on the ground or in the lower
parts of the trees and bushes. Due to the iguana's habitat, its wild diet
consists of a variety of leaves, small fruits and flowers - and this variety
should be provided in captivity as well. It may sound easy to provide a
varied diet for the captive iguana, however the diet must also be a nutritiously
balanced and healthy diet and this is why the iguana owner needs to learn
some basic guidelines for making a proper Iguana-salad.
Photo by Chris Estep
don't recognize what we are trying to feed them as being proper food. They
are attracted by certain shapes and colors, and may, like humans, get 'hooked'
on junk foods, foods that either lack nutritional value or that are downright
harmful to them, or foods that they are simply used to getting. This is
a particular problem with pre-owned iguanas, iguanas being fed less than
ideal diets, and those who have come from pet stores where they have been
fed the generally inappropriate feed usually fed to them. One needs to
learn how to deal with this syndrome, how to be patient, not give in, and
eventually be rewarded with your iguana eating what it should!
There is no simple answer as to what is the best diet for iguanas. Green iguanas are hardy and extremely adaptable and will fare on a wide variety of different diets as long as they all meet a certain basic criteria. When keeping an iguana as a pet, one of the best ways to adjust the diet is to look at the veterinary problems with the associated with the diet at different stages in an iguana's life.
From The Green Iguana Manual by Philippe de Vosjoli
For juveniles up to 2½ years of age:
Daily. Twice daily or continuous availability for hatchlings.
Diet: 85-90% plant matter
10-15% animal protein sources and/or commercial pet diet
Vitamin/Mineral Supplementation: One small pinch of vitamin/mineral supplement per animal,
no more than once a day.
For iguanas 2½ years and up:
Every 1-2 days
Diet: 95% plant matter
5% animal protein sources and/or commercial pet diet
Vitamin/Mineral Supplementation: One full pinch per 2 lbs twice a week or 1/8th of a
teaspoon per 3-4 lbs of body weight per week.
mature females, increase calcium supplementation and protein sources
(up to 15%) starting in late December and through egg-laying.
you go about preparing a salad for your iguana, one of the first things
the you as an owner of an iguana needs to learn is to distinguish between
"good" and "bad" food. The "good" foods are
those food items that can be fed on a daily basis, ones listed in the Basic
Iguana Diet. If you plan to have the iguana free roaming in the
house it is a necessary to find out what plants can be placed in the home.
Only those that are non toxic should present. Please refer to Melissa
Kaplan's Edible Plants page to determine which house plants are safe
to have accessible to the iguana.
There are also those plants which should either be avoided or only be used occasionally (ones every other week). Some of these include: spinach, romaine lettuce, onions, beets, beet greens, celery stalk, Swiss-chard, carrots, bananas, grapes, lettuce, kale, Chinese cabbage, broccoli, turnips, cauliflower and brussels sprouts. However there are some plants that are to be avoided all together. These plants are not edible and may have severe toxic consequences for the animal. Rhubarb is extremely toxic because of the formation of calcium oxalate crystals. For a complete list of plants toxic to iguanas and their pathways of toxicity, please refer to Melissa Kaplan's Harmful Plants complete listing. However, if you would like to view the plants for visual identification you can see the plants at the Cornell University pages of Poisonous Plants. If your reptile does ingest something it should not have, watch it carefully for signs of distress. Signs will usually include respiratory changes (i.e. rate of breathing increases or decreases, breaths become shallower or deeper, breathing becomes labored or difficult), increased salivation, dry heaves, vomiting, lethargy, increased activity, rubbing mouth on ground or other surfaces, scratching at face or mouth, diarrhea or other alteration of feces. Don't wait to see if the signs will abate - call (or have someone call) your regular reptile vet or emergency reptile vet (have these numbers and locations on hand before you need them) and let them know what the animal ate, what the signs are, and that you are on your way. The National Animal Poison Control Center may also be able to offer you pertinent information, but in a potential emergency where time is of the essence, you should get your reptile to a vet who can administer an antidote and supportive therapy as quickly as possible.
Calcium Rich Vegetables, where the Ca : P > 2 - 35% or more of the diet.
Other Vegetables: A variety weekly - 35% or more of diet.
Grain/Fiber sources: Optional - up to 20% of diet.
Fruits: Offer a variety weekly - No more than 15% of diet.
Animal Protein sources: Up to 15% for hatchlings and sub adults. No more than 5% of adult diet.
||We receive a large volume of mail about feeding iguanas meat. A large vocal group of iguana fans oppose this despite the fact that iguanas can and do eat meat in the wild and in captivity. As stated above, animal protein should be NO MORE THAN 5%. Please do not email us further about this.|
Photo by Chris Estep
All greens thoroughly rinsed and chopped or diced. Hatchlings or juveniles
need finely chopped food to aid digestion. Gut Fauna in young iguanas can
be overwhelmed by the large pieces of food.
All vegetables should be fresh or frozen: thawed and served room temperature
or slightly warm, chopped.
All fruit washed and chopped into small pieces designed to be bite-sized
various size iguanas. Bananas served with skin.
Chicken meat chopped. Process food soaked.
guana Diet Chart by Robert Ehrig of the International Iguana Society
Metabolic Bone Disease
Calcium deficiency is the lack of physiologically available calcium. Simply supplementing the diet with calcium will not assure that the calcium will be absorbed through the lining of the intestine and become usable. For the effective absorption of calcium through the intestinal lining an adequate amount of vitamin D3 and the proper calcium/phosphorus ratio is required. It is recommended that in iguanas that minerals be provided in the ratio of 1 part D3 to 2 parts calcium to 1 part phosphorus. These can be added in the form of vitamin supplements such as Rep-Cal® and Terrafauna Vitalife® using the proper dosage.
Calcium deficiency can also be caused by the excessive feeding of oxalic acid. When ingested, oxalic acid has a high affinity for blood calcium. This causes a reduction of calcium levels as well as the formation of a potentially lethal, insoluble substance Calcium Oxalate. Refer to Melissa Kaplan's chart on the oxalate to calcium ratio of selected iguana foods to determine a suitable diet for your pet. Acute cases of ingestion of high levels of oxalic acid is potentially lethal. The deposition of the crystals in the kidneys will cause blockage, necrosis, and ultimately death. One plant to avoid at all costs is Rhubarb. The high content of oxalic acid in the rhubarb leaves are toxic will kill even the largest of the iguanas.
The symptoms of metabolic bone disease will vary depending on a number of factors, such as the age of the animal and duration of the disease. In juveniles, symptoms can include a soft lower jaw and deformities of the back and legs. In larger animals, osteoporosis and fibrous osteodystrophy may occur. These are characterized by the swollen, smooth appearance of the hind limbs and swollen lower jaw. Animals with fibrous osteodystrophy are often initially perceived as rotund, fat animals until they manifest abnormal behaviors, usually the result broken limbs and bones now too weak to support the weight of the animal. Fibrous dystrophy results in swollen limbs due to the deposition of scar tissue around the ever-weakening and thinning bones to make up for the structural weakness.
Visceral gout is a disease caused by the accumulation of urate crystals and characterized by the presence of particular lesions called "tophi". In captive herbivorous reptiles, the primary cause is excessive animal protein in the diet. It is a common cause of death in older iguanas fed a primarily high meat or canned dog food diet. The feeding of meats high in purines have been closely associated with high urate levels in herbivorous reptiles. A secondary cause is the lack of water which is needed to by the iguana to flush out uric acid derivatives. Once present, visceral gout is usually fatal.
Mineralization of Internal Organs/Metastatic Calcification
Once an iguana matures and growth rate tapers, excessive calcium in the diet will be readily absorbed into the blood stream with high levels of vitamin D3 and can accumulate in various internal organs. Over time this will eventually kill the animal. Care must be given to not over supplement the diet of adult iguanas. It is recommended that 100-200 IU/ of D3 per kilogram (2.2 lb) be fed per week. The moral is that too much of a good thing is not always better.
Popular Iguana Links
1. Boyer, T. 1991. Common problems and treatment of
green iguanas (Iguana iguana).
Bulletin of the Association of Amphibian and Reptilian Veterinarians.
Vol. 1 No. 1. pp. 8-11.
2. Frye, F. 1991. A Practical Guide for Feeding
Captive Reptiles. Kreiger Publishing.
3. Troyer, K. 1983. Diet selection and digestion in
Iguana iguana, the importance of age
and nutrient requirements. Oecologia (Berlin) 61:201-202.
4. Vosjoli, Philippe. 1992. The Green Iguana Manual.
Advanced Vivarium Systems.
WARNING: These web pages are only meant to be informative. Neither Cornell University nor the author of this site endorse or recommend the use of these plants.
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