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Written by Dr. Bruce Bogoslavsky
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Central Florida Herp Society
Vitamin and mineral supplements are often added to many reptile diets. However, as with many other products, too much can be as dangerous as not enough. Preparations should contain both fat and water soluble vitamins and minerals essential for proper nutrition. Adding any supplement to your reptiles water may increase the decomposition of the product as well as decrease the reptiles water consumption. Adding supplements to salads may effect their palatability. Commercial supplements should be stored in a cool, dark place and products without expiration dates should be avoided.
Vitamin A deficiency is rare in herbivorous reptiles. Beta carotene, the precursor of vitamin A, is present in green leafy plants, yellow and orange vegetables, and fruit. Yolk remaining at the time of hatching will usually provide adequate vitamin A levels for approximately six months. Vitamin A is stored in the liver; diets heavy in animal protein can deplete these stores. Vitamin A deficiency is most commonly observed in young chelonians fed improper diets. Hypovitaminosis A is the most common cause of nonspecific, inflammatory, periocular disease in reptiles. The disease is usually evident within the ocular, genitourinary, and respiratory systems. Affected animals will exhibit swollen or reddened eyelids and mucous membranes, nasal discharge, or respiratory distress (dyspnea). Hyperkeratosis of the skin and mouth parts may also be observed. In herbivorous reptiles, any vitamin A deficiency should be thoroughly investigated prior to the use of supplemental vitamin A.
Vitamin A overdosage may occur secondary to excessive supplementation. This will occur when a single, intramuscular injection, greater than 10,000U/kg is administered. Liver failure, ictrus, jaundice, depression, and anorexia may all be observed in an animal with a vitamin A overdose. Tissue sloughing can be observed at the injection site when injectable vitamin A is used. The exposed tissue will then become susceptible to bacterial infections. Glucocorticoids will prolong the overdose effect and therefore should not be used in affected animals. There is no evidence that vitamin A can be used to stimulate appetite in anorexic reptiles.
Thiamin (Vitamin B1) deficiency is caused by feeding items that contain the enzyme thiaminase rather than by feeding a thiamin deficient diet. Thiaminase breaks down the animals stored supply of thiamine. Herbivorous reptiles may acquire this disease because thiaminase is found in ferns and ornamental house plants, and by feeding large amounts of frozen vegetables. Freezing decreases vitamin levels and increases thiaminase activity. Carnivorous reptiles may acquire a deficiency because thiaminase is found in fish. Thiamine is necessary for the proper development and function of nervous tissues. A thiamine deficiency is characterized by nervous disorders such as: twitching, spasms, blindness, abnormal posture, and an inability to use specific muscle groups. In snakes, inability to accurately strike their prey can be observed. Thiamin deficiency can also lead to dystocia, egg-retention, and other reproductive disorders. These signs may also be seen with other vitamin deficiencies such as vitamin E or selenium and they may also be related to other disease processes. Treatment with a thiamine supplement usually will correct the problem. Adding a small amount of Brewer's yeast to any frozen food item prior to feeding will also help. When fish is used as a food item, make sure it is either fresh or fresh-frozen. Boiling fish prior to its being fed will denature the thiaminase.
The other B complex vitamins are synthesized by the bacteria and protozoa with the intestinal tract of normal reptiles. Raw egg whites contain avidin, which prevents biotin from being processed within the animal. A deficiency may occur in feeding egg-eating reptiles a diet of exclusively whole raw eggs. Egg-eating reptiles in nature rarely acquire a biotin deficiency because most eggs eaten are fertile and embryonic tissue contains biotin. Occasionally, especially following any antimicrobial therapy, the normal flora will die off, allowing a deficiency to occur. By using vitamin B complex supplementation as well as intestinal culture inoculation, the situation is easily correctable.
Vitamin C (ascorbic acid) is produced within the kidney and gastrointestinal tract of reptiles. A herbivorous diet, rich in green, leafy vegetables and citrus fruits is sufficient to prevent this deficiency from occurring. Affected reptiles will exhibit signs of bruising, bleeding gums, separation and tearing of the skin, and occasionally diarrhea. Administration of Vitamin C, is recommended as part of the medical treatment of infectious stomatitis.
Vitamin D levels will have a direct role on the reptiles calcium level. In carnivorous reptiles, this will occur when the animals are fed skeletal muscle and viscera without the bones. In herbivorous reptiles, this will occur when the animals are fed diets containing oxalates or from low or no exposure to ultraviolet stimulation either from direct, unfiltered sunlight or from full-spectrum reptile lights. Vitamin D deficiency will result in a decrease in the calcium absorption from the large intestine and a subsequent decrease in the quality of bone growth and development. These changes will be more obvious in young, rapidly growing reptiles.
Vitamin D overdosage will cause an excess amount of calcium to be absorbed, resulting in calcium deposits within soft tissues, including the heart. This may occur secondary to oversupplementation or following ingestion of rodentacides containing cholecalciferol.
Vitamin E deficiency is usually related to appalling husbandry practice pertaining to the reptiles diet, such as feeding rancid or spoiled food. Carnivorous reptiles may develop a deficiency because fish is high in saturated fats, resulting in this condition. If fish is fed to a reptile, you need to make sure it is either fresh or fresh-frozen and avoid fatty fish such as goldfish. Signs of vitamin E deficiency include anorexia, steatitis, and swollen nodules under the skin. These nodules are actually abnormal fat deposits, the skin covering these areas is usually discolored yellow or orange. Occasionally, cardiac muscle abnormalities similar to "white muscle disease" in mammals, have been diagnosed in reptiles with a vitamin E deficiency. This myopathy is caused by a decrease in the membrane integrity of the muscle cells, due to a decrease in the antioxidant effect of vitamin E.
Vitamin K is synthesized by the normal intestinal flora of reptiles. Vitamin K deficiency may occur following long-term use of oral antibiotics, or following consumption of animals poisoned with warfarin, strychnine, or other coumadin derivatives. Feeding fresh yogurt, Lactobacillus, or fecal cultures will help replenish the reptiles normal intestinal flora.
When treating sick reptiles, administration of vitamins should be performed with some caution. Most vitamins work as enzymes with other nutrients and this process requires fuel to occur. Administering vitamins to anorexic animals without also administering food, may result in an overdose of the vitamin. There are varied doses of most vitamins for reptiles. Because of this, specific doses should be calculated for each patient prior to their use.
1.) Mader, Douglas: Reptile Medicine and Surgery, W.B. Saunders Company, 1996.
2.) Frye, Fredric: Reptile Care; An Atlas of Diseases and Treatments, Volume 1. T.F.H. Publications. New Jersey, 1991.
3.) Frye, Fredric: A Practical Guide for Feeding Captive Reptiles, Krieger Publishing Company, 1993.