Why you should NEVER use cedar bedding in your chicken coop
For many years, the toxicity of cedar to chickens has been common knowledge, but recently, I’ve seen a lot of chicken keepers, and even a very well-respected hatchery, calling this into question. Is cedar’s toxicity to chickens just a myth?
Is cedar bedding safe for chickens? Cedar bedding is not safe for chickens due to the damaging effects of plicatic acid on chickens’ respiratory systems, the damaging effects of terpene hydrocarbons and aromatic compounds on chickens’ livers, and the carcinogenic nature of cedar dust.
Chicks raised on cedar bedding commonly die, and adult chickens living in coops with cedar bedding may get sick and die, although the negative effects of cedar may be delayed by months or years.
I did a deep dive into the academic literature, and have summarized what I’ve found on cedar bedding here, including:
Full disclosure here: the research on the negative effects of cedar has come from studies of mammals, including humans and rats. I could not find research addressing the effects of cedar specifically on chickens—it appears it hasn’t been done. Read my section below, What about chickens and cedar shavings?, for why the negative effects of cedar very likely apply to chickens as well.
I’ve cited a lot of sources in this article, but there were many, many more studies I read through that had similar results and conclusions. The scientific literature on the harmful effects of cedar dust and bedding is plentiful.
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What is Plicatic Acid?
Plicatic acid is a substance found in cedar wood. The highest concentrations are found in western red cedar, but at least some other cedars contain the acid as well, including eastern white cedar (Cartier et al., 1986). Plicatic acid acts as a fungicide and helps to protect cedars from decay (Daniels and Russel, 2007).
How do chickens get exposed to plicatic acid in cedar bedding?
The main method of plicatic acid exposure is through inhalation. Cedar bedding contains very small dust particles, and it’s these particles that deliver the toxins. It does not matter how ventilated your coop is—it will still contain loads of these tiny particles.
What are the symptoms of illness caused by plicatic acid?
Plicatic acid exposure can cause a wide range of respiratory symptoms, including:
Asthma
Coughing
Phlegm
Wheezing
Difficult and/or labored breathing
Chest tightness
Rhinitis (mucous membrane inflammation)
Bronchial hyperreactivity
Decreased lung functioning
(from Chan-Yeung, 1982; Chan-Yeung et al., 1984)
Can cedar shavings cause death?
Cedar shavings can cause death in small animals, particularly babies. One example is documented in a paper by Burkhart and Robinson (1978) called, “High rat pup mortality attributed to the use of cedar-wood shavings as bedding.”
The authors found the following:
“Pups raised on cedar-wood shavings showed 60% mortality compared to less than 3% for those raised on corncobs or aspen.”
The authors also noted that the pups who lived on the cedar bedding didn’t grow well. The surviving pups were more than 20% lighter in weight than the other pups.
What exactly does cedar do to the body?
Plicatic acid from cedar wood breaks down the cells in the airway and lungs once inhaled. A major study was conducted by Ayars, et al. (1989) to determine for sure that plicatic acid from cedar could damage respiratory cells.
To test this, they exposed human and rat alveolar epithelial cells, rat lungs, and tracheal tissue to a plicatic acid solution. The solution caused disintegration and sloughing of the cells.
The authors said the acid likely causes illness by damaging the airway epithelium. They explained that the concentrations of plicatic acid that they used in their experiments were similar to what you’d expect sawmill workers to be exposed to.
They concluded:
“Our results suggest that plicatic acid… can produce lytic damage to alveolar, tracheal, and bronchial epithelial cells… [and] might promote the chronic lung damage observed in…wood workers….”
The authors also looked at the effects of abietic acid from pine wood and found similar results. This is one of the many reasons I don’t recommend using pine shavings in your chicken coop either. (See Pine shavings in the coop: The secret chicken killer?).
Does everyone exposed to cedar dust get sick?
Not everyone exposed to cedar dust gets sick. In fact, most people exposed to cedar dust don’t get sick (just like most lifelong smokers don’t get lung cancer).
For example, in the Pacific Northwest, somewhere between ~5-15% of the exposed population actually gets sick (Chan-Yeung, 1994), although in men working as sawyers, it may be as high as ~25% (Brooks et al., 1981).
Unfortunately, scientists still don’t understand the exact mechanisms causing illness, or why some get sick and others don’t.
What effects do the exposure period and the cedar dust concentration have on the severity of illness?
Studies suggest that the longer susceptible people are exposed to the cedar dust, and the greater the amount of dust they inhale, the sicker they’ll get.
In one study by Vedal et al. (1986) for example, 6% of workers exposed to low levels of cedar dust (<1 mg/m3 on average) developed asthma, whereas 15% of workers exposed to high levels of cedar dust (>2mg/m3) developed asthma.
Another study of respiratory illness in cedar workers done by Brooks et al. (1981) came up with similar results. In this study, workers with different jobs were exposed to different amounts of cedar dust.
The percentages of these workers who developed cedar dust-induced asthma corresponded again to their degree of exposure. Asthma developed in 24% of sawyers (exposed to 6.8 mg/m3 on average), 10.5% of packers (exposed to 4.8 mg/m3 on average), 5% of splitters (exposed to 3.6mg/m3 on average), and 0% of the deckman (no exposure to cedar dust).
For several more examples, see Demers and colleagues’ (1997) review of the health risks posed by softwood toxins (cedar and other softwoods).
Does cedar wood-induced illness go away when cedar is removed?
Respiratory symptoms do subside for some people when they are no longer exposed, but not for others. In a study of 75 workers who became ill from cedar and then left the industry, thereby stopping their exposure, only 50% had a complete recovery from the illness after an average period of around 3 years (Chan-Yeung, 1982). The other half remained asthmatic.
Can cedar bedding cause cancer?
Cedar and cancer in humans
All wood dusts, including cedar wood dust, are presently classified as human carcinogens based on decades of research. The International Agency for Research on Cancer made this classification in 1994.
A review of the literature by Demers et al. (1997) details that workers exposed to pine and cedar dust (as well as other soft woods) do have an increased risk for cancer (although not as much as workers exposed to hard woods).
They concluded:
“At this time, the epidemiologic evidence indicates that there may be an excess risk of sino-nasal cancer associated with softwoods [e.g., cedar and pine]…”
Cedar bedding and cancer in mice
Cedar bedding is suspected to cause cancer in mice, but this has not been proven definitively.
Sabine et al. (1973), an Australian team, procured a unique strain of mice from a laboratory in the United States. This strain of mice had a 100% incidence of liver and mammary tumors.
However, when the mice were moved to Australia, the incidence of tumors was drastically reduced, and went down to almost 0% by the second generation. The mice in Australia also lived a lot longer.
In order to try to figure out why this was the case, the Australian team switched to U.S. feed and U.S. cedar shavings bedding for their mice (the same type of feed and bedding that was used in the U.S. labs where tumor incidence was 100%).
The incidence of mammary tumors of the mice in the Australian lab then went up to almost 100% as well. The team attributed the mammary tumors to being somehow linked to the use of the cedar bedding, although they could not conclusively prove it.
Cedar bedding’s effects on liver function
Numerous studies show that both pine and cedar bedding drastically increase hepatic microsomal enzyme activities and are cytotoxic to the liver (e.g., Vesell, 1967; Cunliffe-Beamer, 1981; Törrönen et al., 1989; Connors et al., 1990; Potgieter et al., 1995; Pelkonen and Hänninen, 1997).
‘Cytotoxic’ refers to causing cell death.
This means that not only do cedar and pine cause the liver to struggle to process toxins, they also cause cell death and, therefore, liver damage. Unfortunately, it’s “the volatile aromatic amines that give these materials their pleasant aroma” (Carter and Lipman, 2018) that are causing liver dysfunction.
That’s right—that wonderful smell of cedar is a toxic mess.
I’ve summarized many of these studies and what they mean for your chickens in my article, Pine shavings in the coop: The secret chicken killer? Please check this article out to see the devastating effects that cedar and pine shavings bedding have on animals.
Everything in that article that I’ve written about pine also applies to cedar. The damaging effects of cedar on the liver are due to the wood’s dangerous amounts of terpene hydrocarbons and aromatic compounds (Miyamoto et al., 2008; Li et al., 2009).
What about chickens and cedar shavings?
Why have studies not been done on chickens?
I’m honestly not at all surprised that studies on chickens haven’t been done. First of all, 99.99% of chicken studies are done on industry chickens. Caged hens don’t live more than a year or two before they’re slaughtered, and most of them don’t live on bedding. They live on wire.
Broiler chickens do live on bedding, but they’re killed in a matter of weeks. The longest-lived meat chickens might get a couple of months.
Because the industry kills chickens so early in their lives, there is no reason for scientists to study the medium- and long-term effects of cedar bedding (or pine bedding, for that matter) on poultry health. Industry chickens won’t be around that long.
Interestingly, I’ve read dozens of papers on broiler bedding materials, and cedar doesn’t seem to be used in the industry. They do raise broilers on pine shavings, though, which is also dangerous. (See my article, Pine shavings in the coop: The secret chicken killer?).
Additionally, the only reason studies have been done on small mammals is because they are used in drug and disease experiments for human gain. Researchers don’t want bedding materials to affect their results.
This is the sole reason why we have some information on the effects of wood shavings on these small lab animals. Otherwise, we’d be just as in the dark about rodents as we are about chickens.
Why the above studies apply to chickens
Chickens are obviously different from mammals in many ways, so we can’t know for sure that these studies apply to them the same way.
However, chickens have extremely sensitive respiratory systems (Damerow, 2015). They are, therefore, more susceptible to respiratory problems than humans are. It would be very surprising if plicatic acid, which is so toxic for other animals, wasn’t toxic for them too.
Additionally, although research hasn’t been officially done on reptiles either, academic institutions and veterinary clinics take it for granted that reptiles shouldn’t be housed on cedar shavings due to cedar’s toxicity (Barten, 2006; Harkewicz, 2001; Rossi, 2006; Wilkinson, 2015).
Symptoms of cedar shavings exposure in reptiles include:
Skin irritation
Respiratory irritation with secondary infection possible
Contact irritation
Rhinitis (inflammation of the mucous membrane)
Birds are relatively closely related to reptiles. Some scientific classifications include birds as reptiles. Scientifically speaking, birds are modern feathered dinosaurs. If cedar shavings are toxic to not just mammals, but also to reptiles, they are likely toxic to birds too.
On top of all this, many chicken keepers have anecdotal stories about their chicks and chickens either getting sick or dying when exposed to cedar. Some of these keepers also have stories about their chickens getting better as soon as the cedar was removed.
Many, sadly, have lost very young chicks on cedar bedding, much like the poor rat pups in the Burkhart and Robinson (1978) study detailed above.
Of course, anecdotal stories are often not accurate representations of reality (who really knows if cedar is to blame), but when you don’t have scientific studies available, you need to at least consider that the stories could be correct.
Does a well-ventilated coop mean cedar won’t be a problem?
A well-ventilated coop doesn’t protect your chickens from cedar shavings-induced illness.
Sure, the more ventilation you have in your coop, the better off your chickens will be, simply because there will be less dust and fewer aromas in the vicinity. However, a well-ventilated coop doesn’t magically dispel the super fine-grained wood particles present with wood shavings of all types.
I have a 10’x10’ coop that’s super ventilated. It’s so ventilated that when I tried the deep litter method, the temperature in the coop remained the same as the temperature outside. There was so much ventilation, the extra heat produced by the decaying bedding was quickly lost.
However, when I used pine shavings in this coop, there still was pine dust everywhere. You often couldn’t see it, unless the sun shone through the window just right, but I suffered the effects of it. I am very sensitive to dust, so every time I was in that coop, my eyes would water, my nose would itch and run, my throat would burn, my chest would tighten, and I just couldn’t breathe as well.
This is why I stopped using pine. I figured if it was that hard on me, it couldn’t be good for my chickens. Since then, I’ve learned from the academic literature that pine shavings are also very toxic—check out my article on this topic, Pine shavings in the coop: The secret chicken killer?
My point is this: the dust is in your coop, even if you aren’t sensitive to it. No matter how much ventilation your coop has, if it’s filled with cedar bedding, you are exposing your chickens to a very harmful material.
You should also keep in mind that a lot of the sawmill workers who got sick from cedar were working outside. Yeah, that’s right—they were exposed to the cedar dust in the great outdoors, which is much better ventilated than any chicken coop. This ventilation did not prevent them from getting seriously ill.
Another way that chickens get major exposure to cedar particles is through their occasional dust baths in their bedding. They do this even when they have excellent dust bath material available.
Some of my chickens loved to do this in their pine shavings, much to my chagrin. If your chickens ever dust bathe in cedar, they are getting massive exposure to dangerous substances. They are literally covering every inch of their bodies with toxins.
And you also need to keep in mind that when your chickens are walking around on bedding, they are very close to it. Their faces are typically within inches of the bedding. They have a lot higher exposure to the bedding than you do when you walk into your coop.
Just think, with every step your chickens take in that bedding, they’re kicking up more toxic dust.
What about chickens who live on cedar bedding and remain healthy?
Some chickens who live on cedar bedding might be fine. Remember, in humans, only 5-25% of people exposed to cedar dust get sick (Chan-Yeung, 1994; Brooks et al., 1981).
You can compare it to smoking. Most people who smoke their whole lives, even heavy smokers, don’t get lung cancer. The problem is, you don’t know in advance who those people will be, and the ones who do get lung cancer suffer greatly.
Another possible reason that a chicken living on cedar is “fine” is that you just don’t know that they’re affected.
In humans, there tends to be a latency period between exposure and the presentation of symptoms (Chan-Yeung et al., 1973). Some symptoms, like dyspnea (difficult or labored breathing) can take up to 3 years of exposure to develop (Chan-Yeung, 1982).
Theoretically, your chickens could go months or even years without you realizing anything is wrong with them. Then, when they are visibly sick, you’re not even going to think it could be caused by their bedding. After all, they’ve been using it forever, and they’ve always been fine!
Think about it. If you’ve been using cedar bedding for a year or two, and then a chicken suddenly gets really sick, you’re going to think the illness is something new.
Similarly, your chickens’ defenses may be weakened by the effects of the cedar toxicity, and you won’t know it. This means that even if your chickens aren’t sick enough to be visibly symptomatic, they may be more susceptible to catching other illnesses.
This means they may get sick with a different disease, but the reason they got sick is because their respiratory systems were already struggling some with the cedar shavings toxicity. Their immune response was low or their tissues were already partially damaged by plicatic acid, making their respiratory system a gold mine for opportunistic pathogens.
Again, the cedar bedding is not something that will probably come to mind for you when your chicken dies of another illness, even if it did play a major role.
And lastly, different packages of cedar shavings may contain wood with different levels of plicatic acid. Western red cedar has the highest level of plicatic acid, and therefore will harm your chickens much more than other types of cedar.
This doesn’t mean that other cedars are safe for your chickens, however. Eastern white cedar, for example, contains only about half the plicatic acid of western red cedar, yet if still makes people sick (Cartier et al., 1986).
Another thing that may make some packages of cedar more toxic than others has to do with the kiln drying process of cedar. Wood acids are redistributed in wood that is kiln dried, making some parts of the wood hyper-concentrated, while leaving other parts with much smaller amounts (Myronycheva et al., 2018).
As far as I can tell in my research, not a lot is known about exactly how kiln drying of woods affects the chemical components of that wood. Myronycheva et al. (2018) conducted a study where they measured many of the acids and extracts in pine wood after kiln drying. They found that many of these substances had migrated towards the surface of the wood, so the concentrations were highest near the surface and progressively lower into the core.
I suspect this means that some cedar shavings may end up way more toxic than others, simply depending on which part of the kiln-dried wood they came from.
These are all reasons why some chickens raised on cedar might be healthy or falsely appear to be healthy.
Another reason to avoid cedar: Chickens are sensitive to strong aromas
Contrary to popular belief, chickens have a very sensitive and sophisticated sense of smell (Jones and Roper, 1997; Nicol, 2015). This means that many of them are likely sensitive to strong aromas.
When I had pine shavings in my coop, I thought it smelled good initially, but it didn’t take long until it made me feel kind of sick. The smell became overbearing. The smell of cedar is much stronger than pine. If some humans are sensitive to these smells, some chickens likely are too.
If you have wood shavings in your coop—try laying down on your coop floor on your stomach. You’ll see that at a chicken’s level, the shavings smell significantly stronger. Even if the shavings weren’t toxic, they would likely be lowering many chickens’ qualities of life anyway.
Why take a chance with your chickens?
Even if you feel skeptical of the arguments I’ve made here, why risk it with your chickens? There are so many other types of bedding. Go for chopped straw or sand. These are both excellent choices. If you need more info, check out these articles on How to use straw in your coop and How to use sand in your coop.
If you’re absolutely set on wood shavings, aspen is a much better choice (although it still poses health risks). Even pine shavings, which are also very toxic, are a safer choice than cedar. Cedar is the worst of the worst.
Spread the word about the dangers of cedar bedding
I’m sure you can now see why I’m so disappointed to have found Murray McMurray Hatchery’s blog post about cedar possibly being an okay bedding type for chickens. This is a huge hatchery with tons of customers nationwide, so they’re viewed as an authority on these things.
The hatchery blog writer cites a document they found, written by Zobel et al. (1985) at the U.S. Department of Agriculture. The hatchery writer says that he gleaned from the document that “weathered cedar loses its oil and is no longer toxic to insects (see bottom of page 60).”
He continues that he believes this means that cedar must not be toxic for chickens either, and he says he will do more research and get back to everybody soon.
I can’t find an update to that post, and thankfully, the blog writer didn’t fully commit to clearing cedar bedding.
But what was he talking about exactly? Here is the passage in the government document he’s referring to:
“Port-Orford-cedar heartwood was more toxic to termites (Reticulitermes flavipes [Kollar]) than were 10 other woods, apparently because of its oil content (Carter and Smythe 1974). Termites will, however, attack weathered Port-Orford-cedar wood from which the oil presumably has been lost.”
— Donald Zobel and Colleagues, 1985, p. 60
The Carter and Smythe (1974) paper that Zobel et al. (1985) references discusses a single type of termite that apparently can eat the weathered wood of a single type of cedar without dying right away. This in no way means that that the cedar used in bedding has lost its plicatic acid or other cedar extracts.
In fact, we know it hasn’t.
We know that kiln drying pine at high temperatures doesn’t remove the wood’s extracts, including abietic acid (Myronycheva et al., 2018), which is, in a sense, pine’s version of plicatic acid (abietic acid is the main irritant in pine). There is no reason to think that cedar would be any different.
Additionally, cedar itself has been autoclaved (Cunliffe-Beamer et al., 1981) and heat treated (Weichbrod et al., 1988) in experiments to try to eliminate the cedar extracts that cause increased liver enzymes in mice. Both of these processes were unsuccessful. The extracts remained in the bedding.
Early experiments have been started on a groundbreaking new method called soft hydrothermal-processing (Miyamoto et al., 2008; Li et al., 2009). These experiments look promising in removing from cedar at least some of the terpene hydrocarbons and aromatic compounds that cause liver problems in animals, but they unfortunately don’t address plicatic acid.
Despite several experimental attempts, no one has been able to make cedar bedding non-toxic.
So that’s it – I’ve laid a case out before you.
Please help spread the word about cedar toxicity to others who are considering using cedar in their coops. Help save their chickens’ lives!
If you don’t know how to get started spreading the word, please share this post on your favorite social media platform, and pin it on Pinterest!
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