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Heat Rocks - Hidden Dangers

Explaining The Hidden Dangers Of Heat Rocks

Heat Rocks - Hidden Dangers

Heat Rocks - Hidden Dangers

Heat Rocks are used vastly by new enthusiasts because they haven't researched proper heating devices, or haven't read any of the horror stories that surround these things. This short explanation is a compilation of writings from varying sources as to why heat rocks should not be used with captive reptiles, unless you cut the cord off!

My views on heat rocks and their association with captive reptiles:

It is my contention that heat rocks are more of a threat than they are an aid. Whenever there is direct contact between a heat source and a reptile, there is a potential for malfunctions and burns. With the availability of safer alternatives on the market, heat rocks and their use should decline into extinction.

The association between reptiles and their heating requirements is best left to the experts.

Here are some quotes that have been extracted by professional and respected individuals throughout the reptile community. Note that the initials "DVM" stand for Doctor of Veterinary Medicine.

Reptiles: An Atlas of Diseases and Treatments, 1992 - Fredric L. Frye, DVM

Page 157, Figure 5-6a-e. "Some devices that have been used to create convective and radiant warmth for cages. Some are useful; others are not approved."

Figure a (photo of a human heating pad with a 3-way heat switch): "A common household heating pad used for warming sore muscles and sprains. This device in inexpensive, adjustable, and has three heat settings."

Figures d-e (photos of two types of hot rocks): "Two examples of electrical resistance heating devices that are commonly used to provide basking sites for caged reptiles. Often these devices either provide insufficient or excessive heat. Their use should be discouraged in favor of more efficiently and safer sources of warmth."

Burns Chapter - Reptile Medicine and Surgery - Stephen L. Barten, DVM

(Douglas Mader, DVM, ed. W.B. Saunders. 1996. pp. 9-19)

"Thermal burns may result from any source of heat. Heat sources that allow direct contact between the captive reptile and the source, such as hot rocks, heating pads, or spotlights within the cage, are most often implicated in burn cases. Burns may be prevented by keeping heat sources outside of the cage or shielding them to prevent contact with the captive reptile. Backup thermostats should be wired into the system in case the primary thermostat malfunctions."

The following was published in the Herpetological Queries section in the March 1997 issue of Reptiles Magazine. (Bill Love)

What is your position on the use of heat rocks for captive snakes? My local herpetoculturist/store owner says belly heat is unimportant, and it is ambient heat that counts. LJ., Connecticut

As I start pondering the response to your letter, I am thinking to myself, "What does the idea of substrate heating resemble in nature that snakes would normally utilize?" Unless we are using the odd example of a species that inhabits an area with subterranean steam vents or other such rare phenomena, where would most snakes ever have 24-hour access to a toasty warm spot on which to pass their time digesting a meal?

The closest analogy to heat rocks is a serpent basking on a warm road surface (or a sun-warmed rock) as its environment cools after dark. This might be a cozy solution for a few hours at best (and if no cars are coming down the road!). Eventually, though, the animal may have to tolerate some chilling before morning.

The sun is the chief source of heat, mostly in the direct form while radiating heat down from above. Snakes, and many other herps, have learned to adapt to this by developing routines of basking behavior to maximize the sun effectively. Many move into it for a while in the morning, until they reach their desired temperature level for activity. During the rest of the day, diurnal species move in and out of shade to maintain the proper temperature levels. Even nocturnal snakes with meals in their stomachs may spend part of the day in this manner to assist digestive efficiency, knowing that the heat gets "switched off' at night. They simply do not have the option of keeping a perfect temperature all the time and they have obviously evolved to be capable of handling it.

Artificial substrate heating came about as a convenient heat choice because the lack of such options in captivity is the norm. This method is effective for people who are not able to maintain an ambient temperature high enough for heat loving reptiles that may be kept, for instance, in northern basements during the winter. Heating of this kind creates a warm spot in an otherwise cold cage, so digestion can occur, or simply so the herp does not have to endure uncomfortable or dangerous temperatures.

Heat rocks, pads and tapes are particularly handy when the goal is to keep a large number of specimens in rows of tanks or plastic boxes. This type of heating may be more economical than raising the ambient temperature of a large holding area, and it gives a range across the cage. ICs especially suited to offering heat to growing juveniles that may be sharing the same room with adults that you wish to cool for breeding. It can also speed digestion in sick animals.

Substrate heat is more effective for terrestrial species than arboreal ones, although I did see a new heating device at a show, which incorporated heat cable into an artificial tree limb to accommodate arboreal herps.

For snakes, I prefer overhead lamps that more closely mimic the sun as heat sources in cages where it is feasible to use them. They can be aimed at chosen sites to tempt snakes into comfortable, yet easily viewed, places in their cages. Simple spotlights, especially with directional hoods, can be set up over the ends of cages to give the inhabitants the choice of either basking under them or avoiding them by staying at the darker side of their enclosures. Controlled by timers, lights such as this can be set to coincide with the local conditions, offering a seasonal photoperiod in which natural basking (thermoregulation) is also possible. Healthy herps should continue to thrive when exposed to slightly sub optimal temperatures overnight, as long as they can obtain as much heat as desired during the daytime.

Although substrate heat can be valuable, I believe that snakes can better judge the warmth they need from heat coming down from above, rather than from heat rising up through their bellies at night, when it normally wouldn't be available at all. Captivity subjects animals to stresses that we are only beginning to fully comprehend, and keeping snakes at abnormally warm temperatures may be just as adverse as letting them get too cold. This may be why certain diseases and/or parasites that are normally held in check by the course of daily activity in the wild may gain the upper hand in captive animals.

Below is additional supportive information as to why heat rocks are dangerous and why the use of heat rocks should be limited to decorative purposes.

Heat Rocks - Hidden Dangers

General Husbandry and Management Chapter, in Reptile Medicine and Surgery - Sean McKeown

(Douglas Mader, DVM, ed. W.B. Saunders. 1996. Pp. 9-19)

"Historically, the hot rock has been the most misused heating source. It should never be used as the primary heat source. Hot rocks are made of clay, cement or hard plastic molded or formed around an electric resistor (heating coil). As the electric coil heats up, so does the surrounding mold. The reptile is expected to crawl on or coil around this rock and maintain its body temperature. These rocks do not heat the captive environment.; therefore, a reptile housed in a terrarium heated only with a hot rock will not have the proper warmth to meet its metabolic requirements and may receive severe burns. Hot rocks are only effective when buried under the substrate and used as a secondary heat source. Most do not have any built-in means to control their temperature output, resulting in an "all or none" heating system. Although these have somewhat standardized construction, they typically vary in size and heat production. What may be an appropriate size and temperature for a large python may be dangerously hot for a small king snake. Likewise, a small, buried hot rock suitable as a secondary heat source for a small snake would be less effective for a large-bodied snake. Hot rocks are also notorious for having surface "hot spots" that can reach such high temperatures that severe thermal burns can result. Hot rocks are suitable only for ground dwelling species of snakes and must be insulated from the live animal."

Reptile Keeper's Handbook, Chapter 3, The Captive Environment - Susan Barnard, Curator

(p. 26; Krieger Publishing Co., Melbourne FL, 1996)

"Snake usually tend to maintain lower body temperatures than do lizards from the same geographical area, and tropical reptiles generally have less tolerance for low temperatures than those from temperate regions. Some reptiles, especially, tropical forest dwellers, may not display heat-avoidance behavior. Do not, therefore, expose these reptiles to basking spots where temperatures would rise above their selected body temperature. Keep all heating devices on the cage exterior to prevent accidental burns. I do not favor heating devices that require animals to make contact for warmth. Such devices do not increase the surrounding temperature, but provide dangerously localized heat on an animal. Reptiles can suffer burns before they become aware that they have been injured when thermostats are set to high or when they fail altogether. Conversely, thermostats that fail may produce no heat at all, and tropical forest dwellers may develop respiratory problems when temperatures fall below the range that is best for them."

Heat Rocks - Hidden Dangers

As you can see by the extracts provided, noted veterinarians , reptile curators, and authors have a stance of their own. To prevent accidental injuries to your reptile, keep ALL heat sources outside of the enclosure. The use of heat rocks is not necessary and should be avoided! Alternative heat sources are readily available and should be implemented in the deterrence to the use of heat rocks.

So remember, if you want to use a heat rock, CUT THE CORD OFF FIRST!

If you are currently using a heat rock and have just read this article, you can still use the heat rock. The first thing you need to do however is cut the cord off of it. Now place it under a basking light and allow the radiant heat from above to warm it as it would in nature!


Author: Richard Brooks