In the wild, iguanas are warmed by radiant heat: the tropical sun warms up the air. Resting on branches, the iguanas are bathed in the heat that is available to them wherever they move around in their environment. When they are exposed to the sun, they get warmer; when they move into the shade, they cool off. This is called thermoregulating and it's how all reptiles regulate their internal body temperature.

Despite the advertisements showing iguanas happily draped across hot rocks and heated "branches," these products are not suitable for iguanas. Hot rock and sizzle stone manufacturers have jumped on the iguana bandwagon, sticking iguanas in ads for all their products (well, it seems like all of their products!) whether or not that product is suitable for iguanas. Hot rocks and sizzle stones do not heat up anything but themselves and what ever happens to be plastered to them. All too often, their internal temperature regulator fails, and the rock becomes hot enough to severely burn the iguana, sometimes fatally. This includes all of the "new and improved" models that seem to keep coming out every year. (My question is: If the previous model was so "new and improved," why does the manufacturer feel he has to come out with yet another "new and improved" model?)

Many hot-rock using iguana owners insist that their iguanas love their hot rocks. The fact that the rest of the iguana's enclosure is too cool for their iguana doesn't occur to them or they decide it doesn't matter. Most of these owners are just going by what the pet store--or, unfortunately, some outdated veterinarians--told them. Of course, the pet stores and hot rock/sizzle stone manufacturers love it: once you buy the rock and use it, there's no returning it!

The reptile veterinary and the better pet trade literature has for years said that hot rocks should not be used for iguanas. Despite this, pet stores and pet product manufacturers still push them on new iguana owners, and reptile magazines continue to accept advertising depicting inappropriate use. Heated branches have not (that I have yet heard) been guilty of causing thermal burns as have hot rocks. Branches, like rocks, do not heat up the environment and so are unable to provide the type of environment required by the iguana. They are also expensive and your iguana will outgrow it rather soon if you are caring for it properly.

Another product promoted by product manufacturers and pet stores are undertank heating pads made for reptiles. These pads that have a self-adhesive backing and are to be glued to the underside of glass tanks. While this may be suitable for a small terrestrial reptile that will not be outgrowing its tank, it is needlessly expensive for iguana owners. The pads are not designed to be removed from the glass, and could pose a danger if they are removed and reused under or inside a larger tank.