Proceeding of the LAVC Latin American Veterinary Conference Oct , 2009 Lima, Peru

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1 Close this window to return to IVIS Proceeding of the LAVC Latin American Veterinary Conference Oct , 2009 Lima, Peru Reprinted in the IVIS website with the permission of the LAVC

2 Dr. Douglas R. Mader REPTILE ANATOMY IGUANA MEDICINE IGUANA SURGERY BURNS IN REPTILES REPTILIAN RADIOLOGY Página 241

3 IGUANA MEDICINE The saurians, or lizards, as a group have a census of greater than 2800 different species. Among the reptiles the lizards have a greater acceptance or appeal with the pet loving population. In fact, due to their more mammal-like anatomy (a head with a distinct nose, four legs and a tail), most people find them quite fascinating. Iguanas, like snakes and turtles, are ectothermic, or cold-blooded (the old term used to be poikilothermic). The ambient environmental temperature influences the animal's internal body temperature. The internal body temperature has a direct influence on the animal's metabolism, activity levels and its ability to eat and digest food. Temperature also has a direct influence on the lizard's immune system and its ability to ward off disease. The animals are more efficient in resisting disease at the higher temperatures. The habitats provided for Iguanas in captivity should be designed and constructed with a knowledge of their natural behaviors in mind. These large lizards are from the rainforests of Northern Mexico south to Southeastern Brazil. Their daily and seasonal temperature fluctuations barely stray from lows in the mid seventies to highs in the upper nineties, occasionally extending up to 100 degrees. Of paramount importance is the huimidity, which should be upwards of percent or higher. In captivity, separate areas for refuge, basking, soaking, swimming and food collection should all be provided. These animals are not social, and it is best if they are housed wither alone, or in a large enough enclosure to provide spatial separation between individuals. There is a great deal of psychological intimidation between conspecifics, especially between males. Proper nutrition is critical to maintaining healthy Iguanas in captivity. The most frequent types of lizards seen in the pet trade belong to the family iguanidae. There are about 600 different species of iguanids, ranging in size from 4 to 72 inches, but the two which are most commonly marketed are the Green Iguana (Iguana spp.) and the Spineytailed Iguana (Ctenosaurus spp.). There are only two species in the genus Iguana, Iguana iguana, and I. delicatissima. I. delicatissima, the Lesser Antillian iguana, is restricted to a very limited geographical region, just a few islands in the Lesser Antilles, and is not seen in the pet trade. The Green iguanas are folivores. The Spiney-tailed iguanas have somewhat different needs, and on occasion will take a mouse. In captivity iguanas are often wrongly fed canned Página 245

4 dog or cat food, although this practice is not advised due to the excessively high levels of animal protein and animal fat. A better diet would include fresh vegetables (romaine lettuce, string beans, broccoli, cauliflower, sweet potatoes, carrots), small amounts of fruit (less than five percent of the diet), fresh flowers (hibiscus, roses petals, dandelion flowers and stems) and a supplemental vitamin and mineral source (see Table 1). Sex determination is fairly simple for the experienced keeper. Most lizards show some kind of sexual dimorphism (visible difference between the sexes). There are a few gender characteristics which can be utilized for identifying males and females. Both the male and female iguana have a series of scent glands on the underside of their back legs called the femoral pores. These pores are usually much larger in the sexually mature male. Most iguanas don't reach sexual maturity for a few years, so sex determination is quite difficult in the adolescent animals. Another distinguishing characteristic in iguanas is the presence of palpable sexual organs at the base of the tail in the adult males. The male's paired sexual organ, each of which is called a hemipenis, in its non-reproductive position is tucked away within the base of the tail, just behind the opening of the cloaca (the excretory orifice). Because of this the tail is usually broader than the female's tail. After seeing a male and female side-by-side one can easily visualize the difference. In captivity iguanas can potentially live up to fifteen years of age and reach lengths of two meters, and five to seven kilograms. In reality, however, because of mismanagement and improper husbandry, most animals only live a few years. Physical examinations - An individual examination should be performed on each lizard. Start out with a thorough evaluation of the outside of the animal. Ectoparasites, wounds, obvious deformities and other more subtle evidence of internal disease can be ascertained by a carefully scrutiny of the animal s integument. All four limbs should be palpated for deformities, fractures or other injuries. The toes and toenails should be intact and free of lesions. The oral cavity should be clean, the mucus membranes should pink and there should be no evidence of disease. The nostrils should be dry and free of crusts or discharge. There should be no saliva, mucus or bubbles around the lips. The eyes should be clear and without Página 246

5 excretions. Although lizards do not have external ears, they do have an external eardrum called the tympanic membrane. This membrane should be intact. Metabolic Bone Diseases of Nutritional Origin By far, the single, most common condition affecting captive iguanas results from improper nutrition. Metabolic bone disease of nutritional origin is a consequence of dietary and husbandry mismanagement. Nutritional Secondary Hyperparathyroidism (NSHP), as this condition is referred to medically, results directly from a deficiency in dietary calcium, an improper balance of calcium to phosphorus in the diet, or an excess of dietary phosphorus. The ratio of calcium to phosphorus should be in the range of 1.1 to 2.5:1. Aside from the importance of calcium and phosphorus, there could also be a lack of other essential nutrients in the diet, such as vitamin D. Vitamin D is not only required for bone formation, but is also essential in the absorption of calcium from the intestinal tract. If the diet were deficient in this crucial vitamin all of the calcium in the foodstuff would be useless to the animal eating it. The disease typically presents itself in one of two forms. An animal doesn't necessarily have to have both. In the acute form the lizard's symptoms are those reflecting low blood calcium levels. These are manifested as convulsions, bodily spasms or tremors. This is called "Hypocalcemic Tetany" and the onset is usually rapid. This form is commonly seen in gravid females or females which have just delivered a clutch of eggs. Without immediate medical attention this can be life-threatening. External symptoms of the chronic form of the disease correlate with the insidious physiological changes occurring within the animal's body. The body compensates for deficiency in serum calcium by mobilizing calcium from the bones. The bones most commonly affected are the long bones (legs or ribs), the mandible (lower jaw), the flat bones of the skull, and lastly, the bones of the spine (vertebrae). This form of the disease is often associated with poor husbandry practices such as improper diets, lack of appropriated vitamin/mineral supplementation and insufficient exposure to natural ultraviolet light. When the jaw is affected the calcium salts in the bone are replaced by a softer fibrous connective tissue (fibrous osteodystrophy). This results in a pliable lower jaw. The muscles of the tongue are so strong that they deform the lower jaw, thus resulting in a grotesque "smile" appearance. Initial treatment for NSHP consists of correcting any life-threatening conditions such as hypocalcemic tetany, stabilizing fractures and providing nutrients to animals which have stopped eating. Client education and nutritional counseling to correct dietary imbalances and husbandry problems is often all that is needed in mild cases. Injections of liquid calcium preparations (Calcium gluconate, 100mg/kg, deep IM) may be necessary to combat any immediate life-threatening hypocalcemias in the acute cases. Página 247

6 Other treatments include injections of vitamin D 3 and supportive care for any injuries which exist. If the animal can be managed past this critical period, then oral calcium and vitamin supplements can be given to replace the injectable forms. Calcium glubionate at 1cc/kg PO, BID for two weeks, followed by q 24hr treatment until the animal is stabilized, is the author s drug of choice. Patients that show evidence of fibrous osteodystrophy, such as a swollen mandible or long bones, often have difficulty eating or ambulating. These animals respond well to adjucnt therapy with Salmon Calcitonin, a synthetic form of human calcitonin. Calcitonin is given at 50 IU/Kg, then repeated in one week, greatly enhances the patient's recovery. The standard protocol for treatment with calcitonin is as follows: Initial Visit - Evaluate patient (radiographs) Determine plasma calcium 0.1 cc/kg Injacom 100, IM 1.0 cc/kg Neocalglucon, PO, BID Support patient (tube feeding, etc.) 1 week - 2nd Injacom Injection (0.1cc/Kg) 1st Calcitonin injection (50 IU/kg) continue with Neocalglucon continue with supportive care 2 weeks - 2nd Calcitonin injection (50 IU/kg) supportive care as needed NOTE - Hypocalcemic, or patients with low normal plasma calcium should not receive calcitonin until after their calcium has been stabilized. Synthetic Salmon Calcitonin is 40 times more potent than human calcitonin, and can cause acute death if administered in patients with marginal calcium values! Never give calcitonin to a patient that has not had its calcium stabilized. If fractures are present then these will need to be treated. Splints work well for repair of pathological fractures. The bones are often too soft to hold external fixators and intramedulary pins. Remember, however, that an animal which is hypocalcemic will have difficulty healing. The diet must be corrected and the appropriate vitamins and minerals must Página 248

7 be given or the healing process may be prolonged, or even inhibited. The owner should be encouraged to expose the lizard to natural sunlight both during the convalescent period and thereafter. Table 1 - Recommended Diet for Captive Iguanas (Reprinted with permission from: Barten, S. Lizards. in Mader, DR (ed) Reptile Medicine and Surgery. WB Saunders Co., 2006) All plant material is washed, chopped (a food processor is recommended), and thoroughly mixed. This will ensure a balanced diet in that all food items will be eaten, rather than just the favorite or tasty ones. Prepare enough for 4 to 7 days, store in the refrigerator between feedings, and serve at room temperature or slightly warmer. Hatchlings up to 14 inches in length: -Feed twice a day or continuous availability -Plant matter finely chopped or shredded Juveniles up to 2.5 years or 3 feet in length: -Feed once a day -Plant matter fine to medium chopped or shredded Adults over 2.5 years and 3 feet in length: -Feed daily or every other day -Plant matter coarsely chopped Ingredients: EACH MEAL contains ingredients from ALL FIVE of the following categories: 1) Calcium rich vegetables: 30-40% of the diet, 2 or more items per feeding turnip greens, mustard greens, beet greens, kale, collards, bok choy, Swiss chard, dandelions, parsley, romaine, escarole, spinach, alfalfa pellets 2) Other vegetables: 30-40% of the diet, a variety weekly - frozen mixed vegetables, squash, zucchini, sweet potato, bell pepper, broccoli, peas, beans, okra, grated carrot, sprouts 3) Grain/Fiber: optional, up to 20% of the diet - whole grain breads and natural bran cereals Página 249

8 4) Fruits: no more than 15% of the diet - figs, papaya, melon, apple, peaches, plums, strawberries, tomatoes, banana (with skin), grapes, kiwi 5) Vitamin/Mineral Supplementation: Supplementation is advised, because vitamin and mineral deficiencies are common in iguanas. However, calcium and the fat soluble vitamins (A, D, E, and K) can be oversupplemented as well as undersupplemented. To avoid oversupplementation, natural sources from a varied diet is the best choice, with moderate vitamin/mineral use to balance the diet. To date there are no documented studies on specific requirements for any lizard species. Vitamins: Vitamin D3 is the form utilized by reptiles, and this is a better source than D2. Minerals: Avoid those supplemented with vitamins A and D3. Use powered calcium carbonate (cuttlebone shavings is one source) or calcium gluconate. Mix 2 parts vitamin and 1 part mineral. Hatchlings and juveniles: 1 small pinch per feeding Adults: 1 full pinch per 2 pounds body weight twice a week Adult females: 1 full pinch per feeding from December until egg laying Groups: 1/8 tsp. vitamin/mineral mix per 3 lbs. iguana per week A Comment About Animal Protein Sources: This is a highly controversial area. Traditionally, animal protein sources have been recommended in the diets of iguanas. However, in the wild they are folivores, a type of vegetarian that eats primarily leaves. Some iguana books falsely claim that iguanas eat insects until they mature, then switch to a vegetarian diet as adults. This is not the case. They are vegetarians from birth, even though they might occasionally accept unnatural foods such as crickets or even mice in captivity. Even though animal protein sources traditionally have been recommended for iguanas, their necessity has not been scientifically documented, and should be discouraged. Protein should be supplied as a plant-based source. Página 250