Burns in reptiles and amphibians (Proceedings)

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Burns in reptiles and amphibians (Proceedings)

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Oct 01, 2008

Thermal burns in amphibians and especially reptiles are very common injuries seen by herp veterinarians. The exact reason why these animals seem so prone to burns is not understood, but, something about their behavior and their ability, or inability, to sense thermal injury makes them more susceptible to this type of trauma than any other captive animal. The goal of this paper is to discuss burns, specifically what causes burns, how to recognize them as early as possible and treat them as required.

Understanding Thermal Burns in Reptiles and Amphibians

Since reptiles & amphibians do everything slowly, it is not uncommon for an animal to get burned, but not actually show signs of the injury for several days. This is especially true for minor, or first degree burns. This is significant, since burns, even apparently mild injuries, can have severe consequences if not treated properly. In order to be able to treat burns properly, it is important to understand what causes burns, and how to recognize them in their early stages. Special thanks to Dr. Douglas Mader, MS, DVM, Diplomate ABVP (Ca). He has in previous lectures, articles, and chapters in books covered this topic extensively. Please refer to his and other previously published materials for more indepth coverage of the topic1.

Thermodynamics

The study of heat and its properties is called thermodynamics. As herptile veterinarians, we are all familiar with the importance of providing proper temperatures (i.e. P.O.T.Z) to the cage environment. Over the years we have seen the evolution of heating devices from the original "hot rocks" ("Death Rocks") to the more advanced, thermostatically controlled environmental chambers. We have learned that not only must captive reptiles & amphibians have supplemental heat, but, supplemental heat provided in the proper fashion. For instance, a ten foot long python would not fare well with a single, ten inch hot rock. Likewise, a nocturnal lizard would suffer if its cage were heated with a bright heat lamp.

In order for an object to get warm, or "heat up," there must be a transfer of heat from some outside source to the object that is being heated. Heat always moves from a warmer area to a cooler area. As the heat leaves the first object and enters the second object, the first object becomes cooler, and the second object becomes warmer. Eventually, the temperatures of the two objects will become equal. In other words, they will equilibrate. Heat will never continue to leave the first object such that it becomes cooler, resulting in the new object becoming the hotter of the two.

There are three ways that an object can gain heat, or become warmed. These are via conduction, convection and radiant heat.

Conduction is the transfer of heat within an object (such as down a long metal pole) or between two objects that are touching each other. A herpetological analogy here is the use of a "hot rock." Hot rocks, for those not familiar with these items, are a solid, block-like structure, usually made out of brick, concrete, plaster or heavy molded plastic. Imbedded within the rock is some sort of heating coil. When the heating coil is plugged in it generates heat. This heat, in turn, heats up the rock. If a reptile or amphibian crawls up on the rock, the heat from the hot rock will then transfer, via conduction, to the animal. The path of the heat transfers from the surface of the hot rock, through the feet, legs and abdomen of the animal, or whatever parts of the animal are in DIRECT contact with the rock's surface.

Convection, on the other hand, involves the motion of large-scale quantities of matter. In other words, convection usually involves the movement of either gasses (such as air) or liquids (such as water) – and heat is transferred via movement of this matter (e.g. air or water).

In reptiles & amphibians the heat transfer via convection is through exposure to drafts/movements of air or liquids.

Radiant heat transfer involves the flow of thermal energy by electromagnetic waves. In contrast to conductive heating, where objects must be touching, or convective heating, where the matter (gas or water) must touch the object to be heated, radiant heat does not have to have any matter involved (no touching/contact needed for heat transfer).

An example of radiant heat transfer is the reptile or amphibian basking in the sunlight. It is soaking up the electromagnetic radiation produced by the sun's rays. In captivity, this source of electromagnetic radiation is replaced by any number of artificial means - usually a heat lamp or a ceramic heating element .