The Snapping Turtle – Tips for the Practitioner

Introduction

There are eight species of turtles native to Ontario, Canada; seven of which are considered Species at Risk. Included amongst these species is the snapping turtle (genus Chelydra), which is listed as a Species of Special Concern (Fig 1). Snapping turtle numbers are declining due to habitat loss and fragmentation, harvesting for food, as well as road, boating and fishing mortalities. Turtles are on the move from spring to fall, and both males and females can fall victim to vehicular trauma. June is the prime nesting season however, and injuries are most common during that month. Due to the life history of snapping turtles, every adult saved is crucial to their population. The survival rate of eggs and hatchlings is extremely low, and population health depends on almost zero adult mortality. The snapping turtle (Chelydra serpentina) also take 18 years to reach maturity, making their populations very sensitive to even relatively low numbers of adults lost (Ontario Ministry of Natural Resource 2011, Ontario Endangered Species Act 2007, Ashley 1996, Congdon 1994).

Close-up of a snapping turtle

Figure 1. Close-up of a snapping turtle (Chelydra serpentina). Photograph by the Ontario Turtle Conservation Centre. Click image to enlarge.

At the Ontario Turtle Conservation Centre, previously the Kawartha Turtle Trauma Centre, we encourage private practices, emergency clinics, and rehabilitation centers to aid in the initial treatment of these injured turtles. We admit turtles from across the province, and it is extremely beneficial to the turtle to get immediate care locally before transfer. Snapping turtles are incredible in their ability to heal (albeit slowly!) and we cannot stress enough that the injuries can appear horrific, and yet can go on to heal, with subsequent release of the turtle back into the wild. Even extensive facial trauma can be repaired and the “before” (Fig 2) and “after” (Fig 3 and Fig 4) photos are quite remarkable.

The prognosis for snapping turtles with severe facial trauma can be surprisingly good.

Figure 2. The prognosis for snapping turtles with severe facial trauma can be surprisingly good. Photograph provided by Dr. Sue Carstairs. Click image to enlarge.

healing in the snapping turtle.

Figure 3. This image, showing the same turtle from Figure 2, illustrates healing in the snapping turtle. Photograph by Dr. Sue Carstairs. Click image to enlarge.

The recuperative powers of the snapping turtle.

Figure 4. This final image of this same turtle (shown in Figures 2 & 3) illustrates the recuperative powers of the snapping turtle. Photograph by Dr. Sue Carstairs. Click image to enlarge.

Veterinarians and their staff can legally provide emergency treatment to wildlife, however it is the responsibility of the veterinarian in charge to master the techniques and treatments necessary to ensure no harm occurs to the turtle or its caretakers. Wildlife cannot be maintained for rehabilitation purposes without a federal wildlife rehabilitator license.

 

Handling and restraint

Safe handling is essential as even an injured snapping turtle can deliver a nasty bite. When handling, always keep your hands caudal to the turtle’s midsection; their necks are very long and can reach around to this area. The easiest method of restraint involves using your dominant hand to slip underneath from behind, thus picking the turtle up just like a tray of drinks (Fig 5). Never pick the turtle up by the tail, however the turtle can be stabilized by placing the non-dominant hand around the tail base. A toilet plunger placed over the head by a second assistant makes a suitable makeshift ‘muzzle’ for examination purposes and the long handle serves to keep the hands far from the mouth should the turtle get free.

Picking up snapping turtle

Figure 5. To pick up the snapping turtle, slide the dominant hand beneath the turtle’s bottom shell or plastron from behind. Caution: Always keep your upper hand caudal to the midsection of the turtle. Photograph by the Ontario Turtle Conservation Centre. Click image to enlarge.

Short-term housing

A Rubbermaid container lined with a towel makes an adequate holding area. Snapping turtles are very good climbers and will easily escape even a high-sided container, so place a lid with air holes on the tub. See turtles are ectotherms below for temperature recommendations.

 

Anatomic features that influence care

Turtles do not have a diaphragm and instead possess a single body cavity or coelom.

Until mentation and injuries can be properly assessed, do not place the turtle in water or flush the wounds. Injuries often result in open access to the coelom through various sized holes (Fig 6). These injuries can heal very well, but if water is introduced, it can lead to drowning or coelomitis. A positive side to the absence of a diaphragm is that turtles can still breath even with open wounds that expose the lungs.

Traumatic injuries often result in direct access to the coelom.

Figure 6. Traumatic injuries often result in direct access to the coelom. Photograph by Dr. Sue Carstairs. Click image to enlarge.

Turtles are ectotherms so their body temperature will vary with the environmental temperature.

As a result, initial cloacal temperatures cannot be interpreted in the same way as rectal temperatures in mammals. For example, a very high cloacal temperature likely reflects the fact that the turtle was sitting immobile on the side of a hot road, and does not indicate a “fever”.

Heat lamps or ceramic heaters are not recommended during the initial emergency treatment. The majority of these turtles are not fully ambulatory and cannot move adequately from a heat source, so they are prone to overheating. After initial care is provided at room temperature, maintain the snapping turtle at 23-25°C (73-77°F) with a basking spot of approximately 29.4°C (mid-80’s °F).

 

Urgent care tips

As in mammals, trauma invariably leads to some degree of shock, and must be treated accordingly. The staples of fluid therapy and pain management are essential for survival.

Fluid therapy

Intravenous fluid therapy in turtles is challenging for general practitioners—and indeed for those who regularly work with chelonians as well! Intracoelomic fluids are most commonly used. Subcutaneous (SC) fluid therapy is a second alternative, however the lack of skin elasticity can lead to bruising if this is repeated. For individuals not comfortable with intracoelomic injections, short-term SC fluids provide at least some benefit.

Turtles have more conservative fluid requirements than their mammalian counterparts. Begin with a bolus of 10 ml/kg. The indications for crystalloid fluid therapy remain the same as in mammals and Plasma-Lyte® (Baxter), Normosol® (Hospira), and even 0.9% NaCl are suitable. Even lactated Ringer’s solution can be used, although it has been theorized that the addition of lactate is unsuitable in a species that readily uses anaerobic metabolism. However turtles also have a tremendous buffering ability, and so the addition of lactate can easily be tolerated (Mader 2006). Fluid therapy can be repeated over the day, up to 30ml/kg total, according to the individual condition of the patient.

Analgesia

Most commonly used analgesics include meloxicam (Metacam®, Boehringer Ingelheim) (0.2mg/kg SQ SID) and tramadol (Ultram®, Ortho-McNeil-Janssen) (5 mg/kg IM, SC q 72 hours) (Baker 2011). Note: In Guelph, Chiron Pharmacy can compound tramadol. No studies on non-steroidal anti-inflammatory agents have yet been carried out with turtles (Divers 2010, Olesen 2008, Tuttle 2006), so the dosages used are empirical and their efficacy is unknown.

Traditionally intramuscular (IM) injections are given in the forelimbs of reptiles. The presence of a renal portal system was believed to preclude the administration of injectable medications in the hind limbs. Fortunately research in the reptile has shown that injections into the hind limb do not adversely affect the kidneys or impact the effectiveness of the drug (Holz 1997). This is good news when dealing with snapping turtles as IM injections are generally given in the safer, caudal end of the turtle. Subcutaneous injection can also be administered and are generally as well absorbed as IM drug administration.

It is not known how effective lidocaine is in turtles, however topical application is often used, up to a maximum dose of 10 mg/kg.

Stabilize fractures

Wrap unstable fractures with bandage material to reduce pain from movement until more permanent fixation can be provided by a reptile veterinarian or rehabilitation center.

Supplemental oxygen? Probably not

The benefit of 100% oxygen is debatable in reptiles. Turtles can exist in very low oxygen conditions, and in fact 100% oxygen actually decreases respiration, since breathing is driven by oxygen levels and not carbon dioxide as in mammals. In addition, turtles can breath hold for prolonged periods (Schumacher 2006).

 

Common presenting problems

Shell injury

Snapping turtles injured on roads tend to get deep shell scraping injuries to their upper shell or carapace (Fig 7 and Fig 8). Since the carapace is actually made of fused ribs and vertebrae covered by a modified skin, these injuries are extremely painful. These injuries can often extend down through the bone and there is often an opening into the body cavity. So again care must be taken if flushing the wound. Lesions are treated as open wounds and dressed as in mammals. A moisture retentive, occlusive dressing works well, and will also prevent maggot infestation. Change the bandage daily after gently cleaning the wound.

Carapacial trauma typically seen in road injuries in a snapping turtle.

Figure 7. Carapacial trauma typically seen in road injuries in a snapping turtle. Photograph by Michael E. Comella of the Wichita Falls Reptile Rescue. Click image to enlarge.

Severe carapacial trauma in a snapping turtle.

Figure 8. Severe carapacial trauma in a snapping turtle. Photograph by Dr. Sue Carstairs. Click image to enlarge.

For wounds leading to access into the coelom, dress the lesions with sterile gauze and cover with an occlusive dressing such as Tegaderm® (3M Healthcare) to prevent contamination. Again, change dressings daily, paying particular attention to prevent mold and maggots.

Shell fractures can be stabilized once the turtle has been transferred to a reptile veterinarian or wildlife rehabilitation facility. Analgesia is required for non-invasive procedures. For more invasive procedures, general anesthesia is required. Induction, maintenance, and monitoring is very challenging in snapping turtles, and is not recommended for veterinarians that do not anesthetize reptiles on a regular basis.

Head trauma

Other common injuries in snapping turtles involve the head and jawbones. Fortunately the capacity for snapping turtles to heal by second intention is unmatched. Head injuries can appear horrific, but as long as one eye is present and viable the prognosis for release is good (Fig. 2). Defects in the beak can heal remarkably well and rarely affect the turtle’s ability to prehend food.

Jaw fractures are repaired under general anesthesia utilizing orthopedic wire, positioned with the aid of a dental drill (Fig 9). Surgical repair is only performed once the turtle’s condition is stable. (See the cautions for general anesthesia in snapping turtles above).

A snapping turtle that has undergone surgical repair of a mandibular fracture.

Figure 9. A snapping turtle that has undergone surgical repair (arrow) of a mandibular fracture. Photography by Dr. Sue Carstairs. Click image to enlarge.

Fish hook

Fish hooks lodged in oropharyngeal or esophageal tissue are often observed in snapping turtles (Fig 10). Hooks can also be identified on survey radiographs. Ingestion of fish hooks and fishing lines can cause serious morbidity and mortality in turtles, and they should be removed when identified. Removal requires general anesthesia and can be extremely challenging!

Lodged fish hooks are commonly observed in snapping turtles.

Figure 10. Lodged fish hooks are commonly observed in snapping turtles. Photograph by Dr. Sue Carstairs.

Euthanasia

Of course there are times when humane euthanasia is necessary. Remember that the severity of survivable injuries can be much more dramatic in snapping turtles than in their mammalian counterparts, so make the decision to euthanize based on “turtle facts”.

Decapitation and freezing are NOT humane options for euthanasia. Euthanasia is ideally preceded by general anesthesia with an appropriate agent such as alfaxalone (see below), followed by injection of a standard barbiturate euthanasia solution. Euthanasia solution is ideally given intravenously to minimize discomfort upon injection, but if venous access is impractical, the solution can be given intracoelomically.

Alfaxalone (Alfaxan®, Jurox) (not yet readily available in the US) can be given IM or SC and is an excellent agent for turtles. The alfaxalone varies widely depending on turtle species and health status, but generally 20 mg/kg provides good anesthesia in snapping turtles. This can be “topped up” if an insufficient plane of anesthesia is obtained (Kischinovsky 2013, Bertelsen 2011). It is wise to leave the euthanized turtle at room temperature for a day, to ensure cessation of cardiac activity.

If a female is gravid, eggs can be harvested post mortem even after injectable euthanasia, so please check either via radiology or post mortem for the presence of eggs. Eggs can be gently removed from the oviduct and placed in a shallow, plastic container (e.g. Tupperware®) with the substrate, vermiculite moistened with a 1:1 ratio of water by WEIGHT not volume. For instance add 100 ml of tap water to 100 mg of vermiculite and mix thoroughly. Place the eggs in approximately 1.5 in (3.8 cm) of vermiculite, with one-third of the egg protruding and two-thirds of the egg buried (Fig 11). The eggs can then be transferred to a facility like the Ontario Turtle Conservation Centre for incubation. Turtles have temperature dependent sex determination, so it is important to incubate them at a set temperature to achieve a proper gender ratio (Wibbels 1998).

Harvested turtle eggs.

Figure 11. Harvested turtle eggs. Photograph provided by Dr. Sue Carstairs. Click image to enlarge.

For more information

For more information on snapping turtles, visit the Ontario Turtle Conservation Centre website at kawarthaturtle.org or read the Centre’s report, The Road to Extinction, which outlines the most significant threats to snapping turtles. Regardless of your geographic region, please feel free to also contact the Ontario Turtle Conservation Centre via suecarstairs@sympatico.ca for additional advice on caring for the injured snapping turtle. The Centre also provides training through 1-day workshops for those who would like to get more involved.

 

References