Reptile Digestive Health 2: Dietary Considerations
Nutrition and Diet for Your Reptiles
One of the biggest problems I have seen as a veterinarian working with reptiles is nutrition. There are many things that most people that get their first reptile do not understand about basic animal nutrition for their reptiles. I will start with the most complicated first, herbivores and omniviores and finish with carnivores.
One of the most common diseases that you see is Nutritional Secondary Hyperparathyroidism. The majority of iguanas I see in necropsy are afflicted with this disease. In my experience it is the most common disease of herbivorous reptiles.
There has been a bit of confusion regarding this disease out there because there is a closely related and concurrent condition that sometimes gets named as the disease. Some of you may have heard of Fibrous Osteodystrophy or rubber jaw disease. That is the condition that is often seen in pet lizards due to poor nutrition. This is actually not a disease. It is a symptom of the disease Nutritional Secondary Hyperparathyroidism (NSH). Here is how the disease works.
There is a shift to an abnormal calcium (Ca) and phosporous (P) ratio. This is caused by two possibilities. Either there is too little Ca or too much P. The diet being too high in P is not something we see in reptiles, that does not mean that it cannot happen, but it is not the problem we see. It is seen in mammals eating prepared feed rations, but not really in reptiles. In reptiles the problem is too little Ca unless proven otherwise.
The reduction in Ca in the diet causes the body to have a low blood ionic Ca. This triggers the parathyroid gland to secrete parathormone (parathyroid hormone).
Parathormone acts on osteoclasts in the bone and causes them to digest bone, releasing Ca. The released Ca increases blood ionic Ca to a normal level.
This, in the absence of Ca in the diet, is not sustainable. The bones become eaten away and there is in the later stages not enough Ca to keep the blood eucalcemic (normal calcium levels).
The bones are progressively eaten away and become brittle and pathologic fractures are common. The bones that are weak and unstable trigger a response by the body to try to strengthen the bones. Since new bone cannot be laid down due to the lack of Ca, the body starts trying to strengthen the bone by laying down fibrous tissue, essentially scar tissue around the bone.
The fibrous tissue is not rigid, so the bone becomes flexible and rubbery. Hence common name rubber jaw, since the jaw is often greatly enlarged by the layers of fibrous tissue and rubbery. The condition is medically called fibrous osteodystrophy.
Fibrous osteodystrophy is not a disease, though. It is the late stage symptom of NSH.
Once the deformities have occurred, they cannot be undone, but the process can be reversed for the bones themselves, though the fibrous tissue layers will remain, causing deformity of the animal.
Leading Causes in Herbivores and Omnivores
Diet is the major cause. In herbivores, lettuce is the major culprit. Animals should never be fed lettuce, EVER. The lettuce is a diet food for a reason. I has no real nutritional value. Romaine lettuce is sometimes touted as being better, but it really is not. Feeding romaine lettuce may delay the onset of NSH a few months, but it is not a food you can live on. What can you give your reptiles that are herbivores? That is pretty easy. Here is a list of recommended foods.
Commercial diets with balanced nutrition are the best bet. Fluker farms has several diets available as do other vendors. Calcium is very important and make sure there is Ca in the nutritional information.
Redneck food - that's right, collard greens! Collards and the other members of the genus Brassica such as mustard greens and turnip greens are rich in Ca. They can be shredded like lettuce with a mandolin and given to the reptiles. Carrots are nice, but they are not Ca loaded, but they provide other nutrients like carotenoids. Bell peppers can also be added to the diet as can most any pepper. Remember that birds and reptiles do not seem to have capsaicin receptors that act the same way that ours do. They do not seem to get that burning sensation like mammals when they eat hot peppers. I would still not feed your lizard jalapenos or other hot peppers, but ripe bell peppers and mild banana peppers can give them carotenoids and some minerals as well. Paprika (roasted and dried red bell pepper) can also be used. The benefit of using paprika is that it can intensify the color of reptiles by adding red carotenoids that can be incorporated into the carotenosomes in their xanthopores.
Balance the diet with many plant types. Give them treats in the form of nutritious fruits like strawberries, black berries, blue berries, lingon berries and cranberries. Give them bananas too if they will take them, but never let these be major players in the diet. Leafy greens should always be the major fare and do not give fruit if they will preferentially eat it and leave the greens. Make sure they eat their greens.
In omnivores you can gut load their prey with vitamin supplements. There are several cricket and meal worm feeds out there that are supplemented with calcium.
Post a sign in your reptile room that says "lettuce free zone" to remind you not to use lettuce - yes it sounds crazy but it might help.
NSH is not usually a problem in carnivores that eat prey that have bone, but other dietary considerations are.
One problem is constipation. This can be overcome in two major ways.
1) Make sure they are hydrated.Gut load the prey with fiber such as alfalfa pellets or other high fiber diets.
2) If there are other dietary questions, feel free to post your questions and I will respond.
Gut loading prey items can be easy. Sprinkling supplements on alfalfa pellets or other leafy green pellets can go a long way to treating your carnivorous reptile and mice/rats are very good about gut loading.
Insectivores are essentially carnivores that have a taste for insects (yes insects are really a meat. They are animals and you eat their tissues, so they are meat).
Insects are easily gut loaded. Fluker farms makes calcium rich cricket and meal worm feed to gut load the crickets and meal worms with. These work very well.
Direct supplements can only do so much. Most use calcium carbonate as the supplement. The problem is that this is only about 5% absorbable. Translation: feed 100¢ worth of Ca supplement and the animal poops out 95¢ worth and absorbs only 5¢ worth. Not a good investment.
Colloidal Ca is 98% absorbable. Translation feed 100¢ worth of colloidal Ca supplement and the animal poops out 2¢ worth and absorbs only 98¢ worth. A very good investment.
Colloidal Ca is the form of Ca found in plant and animal tissues. You can get colloidal calcium from health stores in water, but it is easier for you to gut load your insects with calcium rich foods. Fluker farms makes a cricket diet that is a gelatin and contains a colloidal form of Ca. You can also gut load the insects with Ca rich leafy greens like collard greens, mustard greens and turnip greens. Once ingested, the prey item's gut contents will be digested by the reptile.