Respiratory Distress is the expected outcome of using cedar (and pine) shaving or wood chips in the bedding for small mammals...
Cedar Shavings and Respiratory Distress: Natural is not Better
Wood chips have been a favorite substrate for small pets for many years. Touted for being natural and insect-repelling, it has since been discovered in the 1990s that cedar chips are toxic to most small mammals. This includes but is not limited to such mammals as rats, hamsters, any type of squirrels, ferrets and others.
All too often, marketers of pet-care products such as bedding and substrate materials slather the words 'all-natural' or 'natural' on their products to create a feeling that this is superior to artificial substrates. Natural does not mean better, and cedar shavings have more been shown in health studies to be unsafe for small mammals.
Long regarded as superior for its ability to rid pets of mites and fleas and reduce the spread of these annoying parasites in pets bedded upon this substrate, cedar wood chips for bedding has been a favorite child in the pet trade industry. Another factor that made cedar wood shavings favorable was the odor-reducing qualities of the cedar which made them very attractive to the keepers of pets. It effectively reduced or masked the smell of animal natural musk (such as is natural in ferrets, even the neutered ferrets emit musk,) odor from fecal spoors and of course, urine.
Cages that have open-air screens this might not show symptoms in your pet as quickly as in aquaria and closed-type enclosures. Cages with glass or solid sides and screen roofs lack adequate ventilation and aromatic vapors would accumulate nearer the living environment.
Cedar Oils are an Insecticide
Cedar (esp. western red cedar “Thuja plicata”) has potent insecticide compounds. Products for killing or repelling moths are often just a sawed block of western red cedar that the user places in their dresser drawer or hangs in a clothes closet as a natural repellent. Moth repellent sprays employ cedar oil for the same cedar toxicity effect. It has been shown that it is these very insecticidal compounds that cause chronic respiratory disease in small mammals.
Respiratory distress associated with cedar dust are a known occupational hazard in that it causes and aggravates asthma in humans. Occupations such as lumber mills that handle cedar forest products have shown correlation with increased cases of asthma in workers. This could include secondary industries dealing with cedar wood such cabinet and furniture manufacturing, cedar fence post production, etc. where sanding and drilling liberate cedar dust.
Humans have a weakly-developed sense of smell and thus are less aware of the irritant qualities of aromatic wood products while small mammals that rely acutely on their sense of smell will suffer more quickly. In the case of an aquarium or semi-closed system cage (those plastic boxes with exercise tunnels comes to mind,) a small mammal would likely develop and succumb to symptoms of cedar toxicity induced respiratory distress fairly quickly.
Pine chips are not as bad as cedar but they also have toxic resins and compounds that irritate the respiratory tract of animals, including humans. While these days it may be improbable to find cedar wood chips sold specifically as bedding material for pets, it is still available for landscaping use around shrubbery for its insect-repelling qualities and other virtues such as moisture-retention, weed and erosion control, etc. Anyone not familiar with cedar and pine shavings toxicity might mistakenly purchase and use these products as sold in the larger bulk packaging in their pet's enclosure.
Manufacturers of pet care products didn't know at the time about toxic cedar respiratory distress in mammals, but by offering a product with a picture of the target market pet on the package were able to market this to an equally unaware public. Anyone that grew up during the time when cedar chips were marketed for pet bedding might dupe themselves into buying cedar mulch meant for landscaping and using it for their small mammalian pets. More warnings about the connection between cedar toxicity and respiratory distress in small mammals need to be stated more prominently on packaging intended for landscaping use.
It isn't the fault of companies that marketed cedar wood products to the pet trade though; it was what was known at the time. Not that many years ago another common product was removed from store shelves for health concerns to humans. The commonly available gardening product vermiculite which is a heat-treated mica soil-lightener, was shown to be toxic to humans.
Vermiculite in the 1990s was found to contain naturally-occurring asbestos, a known lung irritant and cancer-causing agent. While not all vermiculite contains asbestos, much of it does and for over a decade, vermiculite insulation in homes was used. The vermiculite insulation as is in homes is considered to be inert, but if disturbed (such as in home renovation) the health risks mount. Vermiculite insulation removal and replacement has been ongoing in homes built prior to this discovery.
Except for the size and scope of this dilemma, the two events are parallel; it was deemed safe at one time and discovered to be unsafe later. Fortunately in the case of vermiculite (if there can be a fortunate) is that the mention of it possibly containing asbestos gets high priority attention. Mention of possible results of 'respiratory distress' and 'cedar toxicity' in conjunction with using the visually appealing soft curls of cedar or pine shavings in the bedding for rodent pets often gets a curious look of disbelief from the uninformed consumer.
Cedar chips are still used in dog beds and mattresses however. It does not appear cedar chip toxicity or respiratory distress caused by it adversely affect our canine friends and here again, their non-confinement to and lack of direct contact with the product seems to be a contributing factor. But for smaller mammals such as mice, rats, gerbils, chinchillas, squirrels and ferrets, cedar (and also pine) shavings as well should be avoided.
Avoid respiratory distress, health problems and death in your small mammalian pets. Don't used cedar wood chips or shavings. Dried alfalfa hay makes a better substrate for our diminutive furry friends.