It can be difficult to find reliable reptile information. Here are some wonderful dietary recommendations from this year's conference by Dr. Boyer.
What To Feed Reptiles (EX28)
Western Veterinary Conference 2011
Thomas H. Boyer, DVM
The Pet Hospital of Penasquitos, San Diego, CA, USA
Most reptile and amphibian (herps) diseases are nutritionally related; therefore, it is essential that veterinarians be a solid source of nutritional information for owners. Always evaluate dietary history of your herp patients; never assume the owner has good nutritional knowledge regardless of their experience. Nutritional diseases remain rampant in herps including nutritional secondary hyperparathyroidism, hypovitaminosis A, hepatic lipidosis, and hypoproteinemia. Our goal is to prevent these diseases rather than treat them. To do this, veterinarians must be proactive with nutritional advice for their herp patients. On a very simplistic level herp diets can be broken down to insectivores, carnivores, and herbivores or omnivores. Many reptiles have specialized dietary needs that require extensive appreciation of natural history. The following information serves as a foundation for most common species in captivity.
We will assume all reptiles (except snakes and a few nocturnal geckos) need and have adequate ultraviolet light.InsectivoresThis group includes many lizards, amphibians and some turtles. Insects are calcium deficient. Feeding store bought crickets and mealworms without supplementation will cause calcium and protein deficiency. For example calcium (Ca) to phosphorus (P) ratios of commonly fed insects are as follows; crickets 0.2 (0.07:2.6), mealworms 0.1 (0.08:1.2) and wax worms 0.1 (0.11:0.9). Healthy Ca to P ratios for most vertebrates are generally considered one to two parts Ca for each part P. However, many insectivores grow rapidly from hatchling to adult within a year and may require higher calcium diets. For example, consider salt-water crocodiles, Crocodylus porosus, the largest of all living reptiles. Juvenile salties eat insects, amphibians, crustaceans, small reptiles and fish, with an overall Ca:P ratio of 6.7 to 1, primarily because of crabs and shrimp which have calcium rich shells. Adult salties eat any animals they can get a hold of but less crabs and shrimp. The Ca to P ratio of their diet drops to 1.85 to 1. The take home message is that rapidly growing reptiles require much higher Ca:P ratios.Improving the calcium content of feeder insects is simple, feed a calcium rich diet and dust insects with calcium. Originally feeding a calcium rich diet was called gut loading. Unfortunately, over time this has degraded into just feeding any cricket diet. Not all cricket diets are equal. One study showed three out of four commercial calcium fortified dry diets designed for crickets to be fed to reptiles contained no more calcium than unfortified diets. Despite claims on their labels, only one actually increased the calcium content of the crickets (T-Rex® Calcium Plus Food for Crickets). Calcium fortified high moisture cricket waters or high moisture foods are ineffective at increasing calcium content. Assume store bought insects are nutritionally inadequate at purchase. Rather than have owners search for a good cricket gut loading diet the author purchases one in bulk (Mazuri® Hi-Ca Cricket Diet), repackages it in 60-dram vials and forces owners to purchase it. It can be fed to crickets and mealworms and greatly improves calcium content within 24–48 hours. Provide crickets with water (damp paper towel or sponge) but no fruits or vegetables or they will consume those preferentially over the calcium enriched diet.An additional essential method of improving Ca content is dusting with calcium. To dust insects, place Ca powder in a plastic bag with the insects and lightly shake. This method can produce variable results because of the type of calcium used, particle size and electro-static properties. Multivitamins never contain enough Ca to prevent Ca deficiencies regardless of what the label says. Ca carbonate is the most biologically absorbed Ca so it makes sense to use. No P should be in the Ca. A good commercial product is Rep-Cal (Zoo Med Laboratories, San Luis Obispo). Crickets will groom all calcium off themselves, within 30 minutes to several hours at most, so only offer what will be consumed quickly. The author prefers Ca without vitamin D or P as long as ultraviolet light is present.The third aspect to feeding insectivores is to offer a wide variety of insects. Store insects such as crickets, waxworms, mealworms, and super mealworms should be supplemented with commercially available silkworm larvae and tomatoe horn worms, as well as wild caught seasonally available insects including moths, cicadas, fruit flies, flies, grasshoppers, bees (remove stingers), and cockroaches. Insects are easily collected at night around lights or with funnel traps. Sowbugs (pill bugs or rolly pollys) are terrestrial crustaceans which are rich in Ca and avidly consumed. Many insectivores can be trained or naturally take baby mice which are an excellent dietary supplement. Owners often are concerned about pesticide hazards but this author has never seen that to be a problem. Fireflies are toxic to bearded dragons and should not be fed.CarnivoresThis group includes all snakes and crocodilians, many lizards, and some turtles. One reason snakes remain popular is that rodents are a completely balanced diet and are easily procured; therefore snakes are well fed, remain healthy and thus are easy to keep and breed. Most pet stores now sell frozen rats and mice which should be quickly thawed in plastic bags in hot water to prevent a bacterial bloom in the prey's gut (possible if it were allowed to thaw slowly over several hours) which could upset the predator's gastrointestinal tract. For the die-hard reptile breeder still producing mice and rats make sure they feed pelleted rodent diets, not seed mixes or dog food. Live rodents should be stunned or killed prior to becoming prey so that they don't injure the predator. Hamster, gerbils, chicks, lizards, snakes, frogs, toads or fish are also appropriate food items depending on the reptile's preference. It is important for owners to appreciate the natural history of the species they keep as an insight into what the reptile naturally eats. There are no vegetarian snakes!Aquatic turtles do well on Purina® Trout Chow, Hikari® Aquatic Turtle Diet, Nasco® Turtle Brittle, Mazuri Fresh Water Turtle Diet, earthworms, waxworms, crickets, whole fish (guppies, minnows, chopped trout and freshwater smelt) and pinkies or chopped skinned mice. Some species will take dark leafy greens as they get older.HerbivoresThis group is the greatest challenge to feed correctly and includes turtles, tortoises and many lizards. Calcium and protein deficiencies remain a frequent problem for herbivores. A common misconception is that herbivores will select a balanced diet from the foods offered. While this may be true in natural habitat, this certainly is not true in captivity. A common finding in tortoises on screening bloodwork is hypoalbuminemia, which is often indicative of liver dysfunction. The author has been recommending Mazuri® Tortoise Diet with marked improvement in blood proteins within several months. Mazuri recommends feeding Tortoise Diet with good quality grass hay, fresh fruits and vegetables as less than 20% of the total diet. Shell growth is excellent with the Tortoise Diet, no pyramiding or shell softness; the author soaks it for several minutes in shallow water to soften it first then adds it as a top dressing to dark leafy greens and other vegetables. Foods listed below in bold print have a positive Ca to P ratio and are better than light leafy greens.Vegetables: Dark leafy greens that are rich in calcium include collard, mustard, and turnip tops or greens, alfalfa, Bermuda or Timothy hay, kale, Chinese cabbages (Bok-choy, Pak-choi), broccoli rabe (leaves and stems from the broccoli plant, not the florets humans are fond of), clover, and dandelions (flowers, stems and leaves). Note that the outer darker leaves have a higher mineral content than the inner lighter leaves. Other dark leafy greens include red or green cabbages, beet greens, escarole, parsley, spinach, watercress, savoy, and kohlrabi. Flowers such as roses, nasturtiums, carnations, dandelions and hibiscus are excellent. Mulberry and hibiscus leaves are good if available. Backyard grasses (particularly Bermuda and St. Augustine) and weeds can provide free forage which is particularly good for tortoises. Leafy greens with a light green color, such as all types of lettuce (including Romaine), have lower mineral content but are avidly consumed. They should provide only a small portion of the diet. Spring salad mixes and prepackaged salads typically qualify as light leafy greens. Other types of vegetables include alfalfa, radish, clover and bean sprouts, soaked alfalfa pellets, asparagus, bell peppers, Brussels sprouts, carrots, cauliflower, cucumbers, green beans, jicama, mushrooms, okra, shredded parsnips, peas and pea pods, prickly pear cactus pads (shave off the spines), shredded summer or winter squashes, sweet potatoes, and uncooked thawed frozen mixed vegetables (corn, green beans, lima beans, peas, carrots).Be aware of several rampant misconceptions. If fed exclusively long term members of the cabbage family can cause thyroid problems (goiter), but are harmless in moderation as part of a balanced diet. Spinach, beets, Swiss chard and rhubarb have a high oxalic acid content. Oxalic acid can bind with calcium in the intestinal tract and decrease calcium absorption and theoretically contribute to kidney damage. In moderation spinach, beets and Swiss chard should not cause any problems except tortoises won't eat Swiss chard. Rhubarb should not be fed at all.Fruits: Fruits, in general, are mineral poor yet tasty enough that herbivores will consume them preferentially over more nutritious foods. Therefore, limit fruits to a miniscule portion of the diet, more of a treat than a staple. Apples, apricots, dates, figs, grapes, kiwis, melons, mangos, peaches, papayas, pears, plums, prunes, raisins, star fruit, strawberries, tomatoes and raspberries are all fine in small amounts. Herbivores are fond of bananas; unfortunately, they have very little calcium present.When making salads be careful to remove and discard any wires or rubber bands. It is better to chop salad by hand. Food processors tend to turn the salad into mush and reduce roughage. If hand chopped the vegetable portion can be stored for 6 days in the refrigerator but must be allowed to come to room temperature for an hour before feeding. If not using Mazuri or other fortified diets the salad should be lightly dusted with powdered Ca that is phosphorus and vitamin D free. Once or twice a month a very light dusting of multivitamins (Centrum or Herptivite are good ones) can be substituted for the Ca (again if not using a fortified diet).With this information you can make a tremendous impact on the health of herps in your practice.References1. Boyer T. Essentials of Reptiles: A Guide for Practitioners. AAHA Press, Lakewood, CO, 1998.2. Allen M, Oftedal O. Dietary manipulation of the calcium content of feed crickets. J Zoo Wildlife Med 1989;20(1):26–33.3. Finke M, Dunham S, Kwabi C. Evaluation of four dry commercial gut loading products for improving the calcium content of crickets, Acheta domesticus. J Herp Med Surg 2005;15(1):7–12.4. Finke M, Dunham S, Cole J. Evaluation of various calcium-fortified high moisture commercial products for improving the calcium content of crickets, Acheta domesticus. J Herp Med Surg 2004;14(2):17–20. Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker) Thomas H. Boyer, DVM
The Pet Hospital of Penasquitos
San Diego, CA, USA