I think I'll just stay right here on this towel
Crawling into the bedding brawl
I’ve never given pine bedding much thought. In my experience it has always been “common knowledge” that pine bedding is bad for small pets. Recently I received an email from a representative of a wood fiber company, asking me the source of a comment I made regarding a link between pine shavings and respiratory symptoms in small pets.
I found out there is quite a heated debate raging over pine bedding. Most authorities seem to agree that cedar bedding is not a good choice for small pets (watch, I’ll get email from the cedar-cutters union now).
My rabbits don’t use wood shavings as bedding nor in their litter boxes, so they won’t be the, er, guinea pigs in this. I recommend you find the find the relevant scientific studies (precious few though they may be), read them for yourself, discuss them with your vet (and have him/her explain any parts you do not understand) and make your own decisions.
Various beddings – not just wood shavings - can have unwanted effects. One study compared different beddings, and found “A very early report indicated that compared with mice housed on pine sawdust, mice housed on corncob bedding had reduced reproductive success, with a 10% drop in the number of mice weaned (3). In addition, 21 of 24 mice housed on sawdust bore young compared with 16 of 24 housed on corncob bedding, although these differences are not statistically significant. Several explanations were offered, including the possible presence of a mycotoxin in the corncob bedding, but the reason was not definitively identified. Cotton bedding has been associated with conjunctivitis in athymic nude mice (4). Another report compared mucosal immune responses of mice housed on cotton or wood bedding.
Beware opinion pieces; even their referenced sources are sometimes…other opinion pieces. Really. Opinion pieces may also be quoting scientific articles out of context, or simply providing anecdotal information. In “The Truth About Pine Shavings” author Corinne Fayo, a rabbit breeder, states, “Finally we have evidence treated pine is safe from the scientific studies pet owners often quote from (1,3,4,19). The process of heat treating removes the HME inducing agent as demonstrated in the above mentioned studies. It is also mentioned in the National Institute of Health guide to Laboratory animals "Heat treatments applied before bedding materials are used to reduce the concentration of aromatic hydrocarbons" (6\
Fayo's insertion of the word "to" in the above sentence (inadvertently, I'm sure) significantly changes the meaning. The full context of this section of the NIH’s guide, is below:
Bedding
Animal bedding is a controllable environmental factor that can influence experimental data and animal well-being. The veterinarian or facility manager, in consultation with investigators, should select the most appropriate bedding material. No bedding is ideal for any given species under all management and experimental conditions, and none is ideal for all species (for example, bedding that enables burrowing is encouraged for some species). Several writers (Gibson and others 1987; Jones 1977; Kraft 1980; Thigpen and others 1989; Weichbrod and others 1986) have described desirable characteristics and means of evaluating bedding. Softwood beddings have been used, but the use of untreated softwood shavings and chips is contraindicated for some protocols because they can affect animals' metabolism (Vesell 1967; Vessell and others 1973, 1976). Cedar shavings are not recommended, because they emit aromatic hydrocarbons that induce hepatic microsomal enzymes and cytotoxicity (Torronen and others 1989; Weichbrod and others 1986, 1988) and have been reported to increase the incidence of cancer (Jacobs and Dieter 1978; Vlahakis 1977). Heat treatments applied before bedding materials are used reduce the concentration of aromatic hydrocarbons and might prevent this problem. Manufacturing, monitoring, and storage methods used by vendors should be considered when purchasing bedding products.
In the article “Use of soft hydrothermal processing to improve and recycle bedding for laboratory animals”, the following is noted: “We developed a ground-breaking system to improve fresh bedding and recycle used bedding by applying a soft hydrothermal process with high-temperature and high-pressure dry steam.
The results showed that 68–99% of the predominant aromatic hydrocarbons were removed from fresh bedding treated at 0.35 MPa and 140°C for 120 min (‘improved bedding’).
My questions would be:
-Is this ground-breaking technology being used on pet-store grade bedding (if so, up to 32 percent of the toxins can still remain).
-If standard (non ground-breaking) heat processes are used, what portions of the toxins then remain?
By the way, this technology was not developed in the interest of small pets, it was developed in the interest of the pharmaceutical companies, as they were finding that pine bedding was elevating liver enzymes in the rats used for their drug studies, thus confounding the results of these studies.
Breeder Fayo goes on to say: "May I also point out that I have yet to find in a study a reference to pine or cedar causing hepatic toxicity".
Here’s one!
The United States EPAgency’s Air Toxics Website update on Phenol, reports: Chronic inhalation exposure of animals to phenol has shown central nervous systems (CNS), kidney, liver, respiratory, and cardiovascular effects.
Here's another!
In “Cytotoxicity and biotransformation inducing activity of rodent beddings: A global survey using the Hepa-1 assay”, authors Pelkonen and Hanninen report, “Pine shavings beddings, commonly used all over the world appeared in general to be highly cytotoxic. Extracts of corn cob, rice hulls and straws, used in a few laboratories, were practically non-toxic. Some softwood extracts, especially from pine, were also potent inducers of cytochrome P4501A1. Grass as well as hardwood materials were much less active”.
Do your own research. Start with the two articles below, but read their listed references and make up your own mind.
The Toxicity of Pine and Cedar Shavings
Finally, Dr, Lianne McLeod reminds us that there are a myriad of alternative beddings out there, none of which involve wood shavings of any sort.
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Comments
Great articles, Phyllis. I sent them out on our social network without fail.
RabbitMatch.org
My understanding of the "liver issue" related to soft woods was that they affect the liver's ability to metabolize certain substances, most notably anesthesia. In other words - a small animal kept on soft wood bedding might die during surgery even if the veterinarian does everything right and the animal is otherwise healthy.
We use wood pellets, since my one bun ate the corn pellets. Since the wood pellets do not smell of pine or anything else, are they ok?
Emmy: Good question. I, too, use wood pellets. The bag I have says the pellets are made from "pine, oak and other woods". All I can find on the subject are opinion pieces; to my knowledge no one is doing any studies to determine the safety of wood pellets on small pets. The heat treating used in forming the pellets should remove SOME of the phenols, and as my bunnies do not use bedding, the pellets are only in their litter box.
Make sure the pellets contain no accellerants or other additives, and once wet, remove them before they dry (because then they become sawdust). With 4 rabbits, the pellets are an affordable choice for me HOWEVER I am doing an informal study on various beddings/litter substrates and will post an article on my findings in the future.
Still there is nothing that proves non-heat treated softwood shavings are harmful to rabbits. Tons of pet owners use them with no ill effects. The above article just adds to the pine/cedar myth. I suggets the author do some more reading and talk to people who use pine and cedar shavings.
Corinne: The EPA reports that "Chronic inhalation exposure of animals to phenol has shown central nervous systems (CNS), kidney, liver, respiratory, and cardiovascular effects." They didn't mean POSITIVE effects, Corinne.
- The article by Pelkonen and Hanninen states: "Pine shavings beddings...appeared in general to be highly cytotoxic. Some softwood extracts, especially from pine, were also potent inducers of cytochrome P4501A1." 'Highly cytotoxic' - that's not good either. It means that pine shavings bedding is toxic, or damaging, to cells.
- As you are a breeder, I would imagine you are concerned about pine being a potent inducer of cytochrome P4501A1, as this cytochrome "...appears to lead to a leak of oxygen radicals and consequent oxidative DNA damage that could lead to mutation and cancer."
I don't find anything mythical in the above studies conducted by the NIH, EPA, et al., and I think their studies more than prove that pine shavings are not the best choice for pets.
Phyllis, one thing you are not taking into consideration is dose and concentration regarding what you post as "proof". There still isn't evidence that use of pine shavings leads to any problems. My husband is a research scientists so I have run all this by him as well as other researchers have commented on my article which I have posted on my site.
"- As you are a breeder, I would imagine you are concerned,snip> that could lead to mutation and cancer.""
My kits are raised in pine shavings, there have been no health problems short or long term. It appears to me that you blindly believe the pine myth spread by certain groups and you continue to misuse studies to "prove" your point. I have a feeling you don't even understand some of the quotes you have posted.
The big problem with all you anti-softwood shaving people is you simply cannot explain why in the real world people are not having problems.
Also I have a big beef where you say my insertion of the word "to" "significantly changes the meaning". It DOES NOT. If one reads the sentence it looks like the word "to" was left out in error by NIH. With or without it has no impact on the meaning.
Let me know if you ever do find any real evidence. And geocities is shutting down sites later this year so my pine article can be found at buckysbunnies.tripod.com/Care.html
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