Despite its widespread use in the pet trade and for a variety of pet animals, there remains some confusion over the use of cedar--and by extension, pine--as a substrate for animals, especially for prey animals and reptiles.

In the Winter 1994 issue of Wildlife Rehabilitation Today, the director of a bird conservation association stated the question succinctly: "Everyone just says they have 'heard' cedar is harmful, but no one can supply a source of this information, via a study or an authority."

Dr. Richard Evans, a veterinary pathologist who is also associated with the Orange County (CA) Department of Public Health, responded to this question by discussing laboratory findings and practical experience in the use of cedar shavings as has been found by study and anecdotal evidence involving rodents, cage birds and poultry.

Dr. Evans states that the extracts of cedar and other soft woods, such as pine, contain a number of aromatic (volatile) compounds including hydrocarbons, cedrene and cadrol. Naphthalene (the active ingredient in moth balls) is also a member but is a distinct compound.

These compounds are known irritants of skin, and cause not only irritation, but also the degeneration and death of the cells in the respiratory tract. Once this destruction is set in motion, the animals' defensive barrier is eroded, enabling infection by various microorganisms and secondary microbial infections of the lungs. The medical literature notes increased rates of respiratory infections found in poultry which is raised with cedar shavings in the poultry house. Owners of caged birds have noted similar infection rates, particularly in poorly ventilated areas.

In addition to the skin irritation and respiratory tract damage, these compounds activate enzymes in the liver which results in abnormal metabolism of certain drugs, something especially critical for animals undergoing antibiotic therapy or surgery.

Dr. Evans notes that there is also some evidence to indicate that reproductive rates may be affected, and cancers promoted, through prolonged contact with these compounds. And, as with any other chemical or disease condition, the very young and very old are especially at risk.

Symptoms of irritation include clear to discolored fluids discharged from eyes and nose (which may be mistaken for a regular microbial respiratory infection), sneezing, coughing, constant blinking or other signs of light sensitivity, irregular breathing (dyspnea) and possibly regurgitation. In severe cases, the animal may fall unconscious with or without convulsions. Secondary bacterial, viral and fungal infections are all the more likely to attack once the cells of the respiratory system are damaged and destroyed.

While reptiles and amphibians are not birds or rodents, this is nonetheless important for herpetoculturists. If a rodent or bird skin becomes irritated through fur and feathers, think how much faster that may occur in a furless and featherless reptile or amphibian. Snakes and lizards frequently burrow into their shavings substrate, becoming completely covered by the material, breathing air through the layers of piled up shavings.

With the similarity of the symptoms of cedar toxicity to other common reptile ailments, it is easy to see why toxicity may go undiagnosed. We will never know just how much that housing breeders on cedar may have affected their reproductive success, nor how many recurrent respiratory infections are due to other than stress and too-cool temperatures conditions in the animal's enclosure. Birds and rodents are both warm-blooded animals and as such have consistently rapid metabolisms. Herps, on the other hand, have metabolisms that fluctuate depending upon their environmental temperature and mealtimes. Many herps that don't feel well will stay in the coolest part of their enclosure, thus slowing down their metabolism, and slowing the effects of any substance ingested or absorbed into their bodies.

You might want the rethink buying prey that has been raised or housed on cedar. Evaluate the health of every animal whom you have housed on cedar and pine (after you clean out the cedar and any residual oils in their enclosure). If you see pet stores housing rodents on cedar or pine, you may want to discuss this matter with them, requesting them to change and, if they fail to, purchase your prey and pet rodents elsewhere.