- Make sure the patient is hydrated and warm before initiating nutritional support.
- Chelonians display a variety of dietary strategies. Many tortoises are herbivores while some species such as the Eastern box turtle (Terrapene carolina) are opportunistic omnivores. Juvenile omnivores often eat diets higher in fat and protein.
- When trying to determine if nutritional support should be initiated in an anorectic turtle, determine if the species normally brumates in the wild. “Brumation” is a period of fasting and reduced resting metabolism. Species enter this period of dormancy for weeks or months as an adaptation to excess heat or cold, drought, or lack of food.
- Many gravid females also eat less or go off feed entirely.
- Regular weighing is recommended for fasting reptiles.
- Maintenance energy requirements (MER) in the reptile are derived from equations for Standard Metabolic Rate (SMR) 32 (BW0.75) where BW is in kilograms. MER is expressed in kcal/d and are based on values at 86°F (30°C). In the debilitated patient, only a fraction of the MER is offered at the first feeding and all volumes offered are increased only gradually.
- Small amounts of brightly colored produce such as strawberry, tomato, melon, banana (with peel), yellow squash, and cooked sweet potato can attract the attention and stimulate the appetite of many chelonians. Live fish of appropriate size can attract the attention and stimulate the appetite of aquatic turtles.
Turtles and tortoises display a variety of dietary strategies ranging from the complete herbivory seen in many tortoises to the strict carnivory displayed in aquatic species like the snapping turtle (Chelydra serpentina) (Fig 1). There are also many chelonians, such as the Eastern box turtle (Terrapene carolina), that may be considered opportunistic omnivores (Table 2). Although the table below is intended to make chelonian nutrition as straightforward as possible, their nutritional preferences are not always clear cut or consistent. For instance, many juvenile omnivores, like the Box turtle and the red-eared slider (Trachemys scripta elegans), eat more protein and fat. Although McCauley et al did show that juvenile sliders could meet their energy and nitrogen needs with a plant-based diet. Another species that does not easily fall into a man-made category is the hingeback tortoise (Kinixys spp.), which is an herbivore-insectivore. Although the bulk of the diet is plant-based, this species will also eat pill bugs, earthworms and snails.
|Table 1. Dietary strategies in turtles and tortoises.|
|Dietary strategy||Gastrointestinal tract||Primary sources of dietary energy||Examples||Prey items|
|Carnivore||Relatively short and simple gut.||Fat, protein||
|Omnivore||Fat, protein and soluble CHO||
|Herbivore||The distal gut is relatively large for bacterial fermentation of fiber.||Fermented fiber and soluble CHO||Most tortoises (family Testudinidae)||
See The self-feeder for more details.
Recognizing true anorexia
Fasting may be expected in some species during certain times of the year. For instance, many gravid females eat less or go off feed entirely. Some species also fast for weeks or months as an adaptation to excess heat or cold, drought, or lack of food. This dormancy in reptiles is called “brumation” as opposed to true hibernation. Because these normal periods of fasting are associated with slowed metabolism, little energy is consumed and very little weight loss occurs. Box turtles may lose less than 5% of body weight during winter dormancy. Many temperate zone turtle and tortoises must be brumated to induce successful reproduction, and fasting may be seen in some captive specimens, such as box turtles, even when kept warm with adequate food and water.
Brumation is not without risk, and should only be practiced by experienced owners. Prolonged or multiple fasts in less than ideal conditions can be debilitating, and brumation can lead to starvation in thin or sickly reptiles. Regular weighing is therefore recommended for fasting reptiles. Box turtles, for instance, are accessible when wintered in a cool room or refrigerator.
Is nutritional support indicated?
When trying to determine if nutritional support should be initiated in an anorectic turtle or tortoise, ask:
- Does this species normally brumate in the wild?
- Is there weight loss?
- What is the chelonian’s body condition?
During brumation, a healthy specimen will lose relatively little body weight, however improper or prolonged fasting can lead to starvation and debilitation. A chelonian in good body condition should feel dense when lifted. Muscle, and small to moderate amounts of fat, should be palpable over bony protruberances.
Also obtain a detailed dietary and clinical history and look for evidence of disease on physical examination. Laboratory diagnosis of starvation may be difficult. Blood glucose and electrolyte levels decrease inconsistently. Low albumin levels may also suggest malnutrition. Imaging may also prove helpful. Use radiographs to rule out gastrointestinal obstruction or impaction. Ultrasound may be used to look for the presence of intracoelomic fat bodies.
It is a common clinical mistake to feed chelonians too quickly. Ensure the reptile is hydrated and warm before initiating nutritional support.
- Reptiles are ectothermic or poikilothermic. Body temperature varies with environmental temperature rather than changes in internal metabolism. Therefore provide these animals with an appropriate temperature gradient and humidity. (See Hospitalizing Non-Traditional Pets for more specific advice). Requirements can vary widely. For instance, a species native to the desert, such as the Sulcata tortoise (Geochelone sulcata) has very different relative humidity needs when compared to a temperate zone species such as the Eastern box turtle (Terrapene carolina) (Table 1). Although desert species like the Sulcata tortoise thrive in temperatures approaching and exceeding 100°F (37.8°C) when outdoors, those indoors in small enclosures, especially juveniles, can be killed by exposure to too-high temperatures without a suitable gradient. Likewise, box turtles outside do fine when nighttime temperatures are 40°F (4.4°C) and below, but when enclosed in small quarters inside more moderate temperatures are required.
|Table 2. Husbandry requirements of the Sulcata tortoise and box turtle.|
|Box Turtle °F (°C)||Sulcata Tortoise °F (°C)|
|Preferred temperature gradient||70-80 (21-27)||70-100+ (21-) adults outside|
|Basking temperature||85-90 (29-32)||100+ (3) adults outside|
|Nighttime low||40-75 (21-24)||70s (21-26)|
- Dehydration is common in sick reptiles. The dehydrated reptile will be depressed and anorectic with sunken eyes and dry loose skin folds. Maintenance fluid replacement has been estimated at 10-20 ml/kg/day for chelonians or turtles or tortoises.
What should be fed?
Chelonians with loss of body weight and body condition that are still clinically healthy, may be fed solids. For advice on how to encourage self-feeding see below. Critically ill chelonians should be tube feed a formula that is easily digestible and highly absorbable. Use the Emeraid Nutritional Care System to meet the needs of your specific species.
How to tube feed a chelonian
- Weigh the patient on a gram scale.
- Restore fluids and electrolytes, when indicated, and house the patient at its preferred optimum temperature gradient.
- Calculate daily caloric requirements estimated as 32 (BW0.75) where BW is in kilograms. Maintenance energy requirements are expressed in kcal/d and are based on values at 86°F (30°C). (Donaghue 2006). Since the turtle shell is metabolically active, this equation is that same as that used for other reptiles even though the shell makes up 15-30% of BW and the caloric utilization rates specifically for the shell are unknown (Kuchling 1997). Caloric needs increase in patients with shell trauma (Donaghue 2006).
Table 3. Estimated daily maintenance caloric requirements (1XSMR) in reptiles based on 32 (BW0.75)* Body weight (grams) Daily caloric requirements (kcal/day) 5 0.60 10 1.01 25 2.01 50 3.38 75 4.59 100 5.69 150 7.71 200 9.57 300 12.97 400 16.10 500 19.03 600 21.82 700 24.49 800 27.07 900 29.57 1000 32.00 2000 53.82 3000 72.94 4000 90.51 5000 107.00 10,000 179.95 15,000 243.90 20,000 302.64 25,000 357.77 30,000 410.20 * BW stands for body weight in kilograms; based on values at 86°F (30°C) (Donoghue 2006)
Data in turtles suggests that the “refeeding syndrome” may exist in reptiles (Da Silva 1990). Over-feeding of a starved, critically ill patient can lead to life threatening falls in potassium and phosphorus levels. Rapid administration of calories, particularly carbohydrates, predisposes a patient to “refeeding syndrome”.
- Also keep mechanical limitations in mind when tube feeding. The stomach capacity of the turtle is estimated at 2%-5% of body weight. So the stomach of a 100 gram turtle should be able to hold somewhere between 2-5 ml of formula.
- Select a stainless steel feeding needles or gavage tube with relatively wide bore. Whenever possible, the tube should be long enough to reach the stomach located approximately at the halfway point of the turtle.
- Use a speculum to hold the mouth open (Fig 2). Some bird speculums or padded hemostats can serve well. Take care not to injure the keratin surfaces of the beak.
- Hold the cranial half of the chelonian up for a minute or two after feeding to minimize the risk of regurgitation (Fig 3), particularly if the tube used was not long enough to reach the stomach.
- Minimize handling for at least a few hours after tube feeding to reduce the risk of regurgitation.
- Monitor the patient for stool production. Fecal volume will decrease in patients fed a highly digestible diet such as Emeraid; this is normal and expected.
- If fluid therapy is continued, keep track of the amount of fluids in the tube feedings to reduce the risk of overhydration.
See Lafeber Vet’s video clip on Nutritional Support in the Reptile for an example of tube feeding a turtle.
Permanent tube placement
Pharyngostomy or esophagostomy tubes are commonly placed in chelonians that require continued nutritional support. The mouth is often very difficult to open even in weak chelonians making tube placement preferable for patient and hospital staff alike. Tube placement is also indicated in overly aggressive patients. Sedation is often required to facilitate tube placement and minimize patient stress. Refer debilitated turtles and tortoises to a reptile veterinarian for tube placement.
To stimulate voluntary feeding, house the chelonian at a temperature gradient appropriate for the species. The presence of basking lights and water baths may also help stimulate the appetite. Flat plates or lids are preferred to bowls for many turtles and tortoises, but low dishes do allow the reptile to walk in its food so watch out for fecal contamination of food items.
The adult Eastern box turtle is an opportunistic omnivore. Juveniles tend to be more carnivorous. The diet may consist of approximately 50% protein sources and 50% plant material (Table 4). The bulk of the vegetables (75%) fed should be foods rich in vitamin A such as dark green, orange, and yellow vegetables that have been chopped or grated (Fig 4). Foods underlined may particularly likely to be eaten by the hospitalized Box turtle (Donoghue 2006).
|Table 4. Box turtle food items|
|Bolded food items are particularly popular|
Most tortoises are generalist grazers that readily consume legumes such as alfalfa, clover, kudzu, lespedeza, vetch as well as grasses like johnsongrass, bluegrass, orchard grass, timothy, and crab grass. Larger species like the Sulcata tortoise also browse cactus, bushes, shrubs, and vines like rose, grapevine, and kudzu (Fig 5).
Grassland tortoises such as sulcata, leopard (Stigmochelys pardalis), star (Geochelone elegans), and Testudo spp., eat mixtures of grasses and forages mixed with other vegetation to create a “salad”. Tortoises from desert or arid environments tend to accept and better metabolize drier foods like hay and cacti. Fruits are fermented rapidly and can lead to diarrhea. Any fruit offered to these species must be balanced with enough chopped dry forage to maintain crude fiber intake >15% DM.
Forest tortoises such as the red-foot (Chelonoidis carbonaria), yellow-foot (Geochelone denticulate), and elongate tortoise (Indotestudo elongate), may consume more fruit (Fig 6). These species seem to relish moist sweet foods like kiwi, guava, pineapple, plaintain, and watermelon. Small amounts of brightly colored produce such as strawberry, tomato, melon, banana (with peel), yellow squash, and cooked sweet potato can attract the attention and stimulate the appetite of any hospitalized. Blooms such as dandelions, hibiscus, and roses may also be favorite treats.
Although frozen foods are economical and convenient for short term feeding, offer fresh items whenever possible. Wash all fruits and vegetables, and remove and/or soak wilted leaves. Grate or chop salad into bite-size pieces, and whenever possible, allow the salad mixture to reach room temperature for 30-60 minutes before feeding it out.
Feed adult tortoises three times weekly minimum. Feed hatchlings daily.
Food items to avoid
Avoid feeding in large quantities:
- Broccoli, kale, bok choi, radish (contain goiterogenic or iodine-binding substances)
- Spinach, beets, celery stalks, carrots (high in oxalates)
The following vegetation may be toxic to reptiles based on anecdotal reports:
During a short-term hospital stay, vitamin-mineral supplementation may not be absolutely necessary. Long-term feeding requires supplementation for good health.
- Dust food with a powdered calcium supplement (preferably calcium carbonate or calcium gluconate) at every meal.
- Dust food with a multivitamin every 2-4 weeks. Donaghue (2006) recommends the vitamin supplement contain 100 parts vitamin A to 10 parts vitamin D3 to 1 part vitamin E.
Unless the chelonian is extremely weak, make water available at all times. Turtles and tortoises will drink from shallow dishes, but whenever possible also provide a large, sturdy container that allows easy entry and exit for soaking. The tub should be shallow with sides only as deep as the turtle’s legs are long. Soaking enhances water uptake and stimulates eliminations. While soaking, the chelonians may take up water into its cloaca through a process called “cloacal drinking”.
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