Can reptiles experience global warming ? Heatstroke or Hyperthermia in Reptiles

Heatstroke or Hyperthermia in Reptiles
By Dr. Pongphak Pitakpong (Dr. P), Khwankham Animal Hospital, Khon Kaen

Reptiles can experience heatstroke or hyperthermia, just like other animals. However, the symptoms are often harder to observe. Let’s dive into it.

When reptiles are kept in environments where they cannot choose a cooler area to escape the heat, particularly in confined spaces, they are at risk of elevated body temperature (hyperthermia). This condition can occur during the summer or even in other seasons when the animal is exposed to direct heat, resulting in heatstroke. This happens when the body absorbs more heat than it can dissipate and cannot maintain thermal regulation by adjusting the hypothalamus's temperature set point, like warm-blooded animals do.

In the wild, reptiles can find shelter when the temperature deviates significantly from their preferred optimal temperature zone (POTZ). Dangerous temperatures are those higher than 36°C or lower than 4°C, and prolonged exposure can be fatal. In extreme heat, reptiles may aestivate (temporary dormancy) or reduce their activity, similar to what happens in desert environments. In such cases, they may seek deeper burrows or areas between the desert and shrubland. If the heat becomes unbearable, they may prolong their dormancy, only emerging when it is cooler. Reptiles in colder regions may hibernate during the season.

When the environmental temperature exceeds a reptile's tolerance, and it accumulates more heat than it can dissipate, the body temperature rises, leading to dehydration, a drop in blood pressure, and impaired circulation to vital organs like the brain, kidneys, and liver, which can result in organ ischemia (lack of blood supply).

Factors that contribute to excessive heat exposure, aside from limited space, are often associated with open enclosures with no shade, poor ventilation, lack of water, insufficient burrows or digging areas, obesity (which hinders heat dissipation), old age, overcrowding, stress, or even anesthesia.

In their natural habitat, marine animals are less affected by heat since the environment is more stable, known as a "homogeneous environment." Deep seas have a minimal impact on temperature, unlike terrestrial reptiles, which live in "heterogeneous environments" and must adapt by migrating, seeking shelter, or digging.

The inability to choose a proper living space and improper management increases the risk of heatstroke in reptiles. Therefore, owners and veterinarians should monitor temperature and humidity changes, measure water temperature for aquatic reptiles, and ensure proper ventilation and environmental management to minimize the risk of heatstroke.

How do reptiles sense heat differently from other animals?
Reptiles have a much poorer ability to detect heat via nerve endings compared to mammals. This can result in burns, often seen in snakes that coil around heat lamps. However, they can sense heat through infrared receptors in specialized organs like the pit organs, found in some species. They also rely on their pineal gland, which is important for detecting light and heat. Crocodiles have specialized dome pressure receptors on their heads that help them assess surrounding temperatures.

Symptoms of heatstroke in reptiles may include weakness, inability to hold onto surfaces, dehydration, reduced excretion, mouth open, labored breathing, drooling, disorientation, or even seizures, which can lead to death in extreme cases. Severe cases might show burns on the skin, internal organs may overheat, and inflammation or organ failure can occur.

When reptiles enter aestivation due to heat, their metabolism slows down, similar to hibernation during cold weather. If the temperature does not return to a suitable level, the reptile can die.

Other Protective Mechanisms in Reptiles
Besides behavioral adaptations, reptiles have a mechanism called "heart rate hysteresis." This is a slow response to environmental changes that affect heart rate. When body temperature rises, heart rate increases, while it decreases when the temperature lowers. This mechanism helps reptiles manage their body’s metabolic rate under varying temperatures.

Diagnosis involves taking a detailed history, measuring body temperature, and performing a physical exam.

Treatment should be administered promptly upon recognizing heatstroke. Cooling the reptile gradually is crucial—rapid cooling can cause shock. Supportive care, including fluid therapy and anti-inflammatory medication, should also be provided.

Prevention of Heatstroke in Reptiles:

✔️ Ensure proper ventilation in enclosures with ample shade and provide fresh, clean water.
✔️ Allow enough space for the reptile to seek refuge, hide, or dig, and provide a wet/dry zone for temperature regulation. Aquatic reptiles should have large enough tanks to allow temperature regulation in different water levels.
✔️ Regularly measure temperature and humidity with accurate thermometers and hygrometers.
✔️ If the enclosure is too hot, help reduce the temperature using fans, misting, or water spraying.

By managing their environment appropriately, reptiles can be protected from the dangerous effects of heatstroke.