2019 update: The Pet Poison Hotline gets the final word, in my opinion. Here’s what they say:
“Essential oils can pose a toxic risk to household pets, especially to cats. They are rapidly absorbed both orally and across the skin, and are then metabolized in the liver. Cats lack an essential enzyme in their liver and as such have difficulty metabolizing and eliminating certain toxins like essential oils. Cats are also very sensitive to phenols and phenolic compounds, which can be found in some essential oils. The higher the concentration of the essential oil (i.e. 100%), the greater the risk to the cat.“
“Like oil and water, essential oils and cats really do not mix. Owners should be cautious using essential oils and diffusers in their homes in order to protect their cat(s) from a toxic risk. Most importantly, concentrated essential oils should never be directly applied to cats.“
I received a new post from a holistic vet I respect and often quote, Dr Karen Becker. The title was “Forget everything bad you’ve been told about essential oils for pets.”
My first thought was:
“This could be great news! I hope she will assure me once and for all that I don’t have worry about using essential oils – which I love – around my cats.”
My second thought was:
“Wait, this better be very convincing. I don’t want to use or recommend something that could hurt cats.”
My third thought, after reading, was:
“Uh oh, I’m not totally convinced.”
Let me explain.
The scientific origin of essential oils concerns with cats
Dr. Becker’s article doesn’t go into the fact that cats are known to be lacking in an important liver detoxification enzyme called glucuronosyltransferase.
This little enzyme, as Wikipedia explains, is key to the detoxification of the top 200 drugs, as well as most foreign environmental chemicals. Wikipedia’s article on glucuronosyltransferase goes on to say that these enzymes are…
“…famously…not present in the genus Felis, and this accounts for a number of unusual toxicities in the cat family.”
We now know, for instance, that this is why Tylenol and aspirin can be fatal to cats – their livers cannot clear these substances safely even though most others mammals (like you and I) can.
Here are a couple recent research studies published on cats and their “unusual toxicities.”
- PLoS One. 2011 Mar 28;6(3):e18046. Evolution of a major drug metabolizing enzyme defect in the domestic cat and other felidae: phylogenetic timing and the role of hypercarnivory.
- Pharmacogenetics. 2000 Jun;10(4):355-69. Molecular genetic basis for deficient acetaminophen glucuronidation by cats: UGT1A6 is a pseudogene, and evidence for reduced diversity of expressed hepatic UGT1A isoforms.
A few things I discovered:
- I will never be a chemist – this stuff is very rough reading.
- These studies are so recent that most vets would not have learned of them in school.
- These studies mention cats have trouble detoxifying “phytoalexins” and “phenolic”-like substances found in nature. Herein lies controversy over which substances in plants and flowers – and how much – could tax or harm a cat’s liver. These substances in essential oils are hundreds of times more concentrated than in fresh flowers and plants.
- There is a nice lady named Sue Martin who published a whole website on this topic, called The Lavender Cat, which has been transferred to this PDF after the website went offline. You can also view her original interviews with doctors, etc, (via the Way Back Machine) here.
Here’s the thing that worries many of us cat-a-holics:
Though there are only a few reports of cats becoming severely sick or dying because of essential oil exposure, the liver is essential to a healthy immune system. So a taxed liver, over time, means our cats become vulnerable to diseases like cancer.
In fact, there is a known association between toxin exposure and lymphoma. Lymphoma is more common in cats than humans now. I suspect the cat’s detoxification limitations (not essential oils in particular, but all toxins) may be the reason.
Did I ever use essential oils around a cat?
I sure did – essential oils were in my bath, in diffusers, in my hand lotion. But that story did not end well.
Bastet got high-grade lymphoma and died after barely turning 12. As you may know, I believe there were a number of other factors that probably contributed to the cancer, but this is a possible factor I can pretty easily not repeat.
In spite of the carefree title, I hope others don’t walk away from Dr. Becker’s article assuming there is no need for caution.
The overarching message of the article at first scan seems to be “don’t worry about using essential oils with cats at all – as long as you use high quality oils, no problem!”
But there are bits of caution in this article that are easily overlooked:
- Fresh plants are 500 – 2000 times weaker than essential oil concentrations. The post includes the idea that The cat likes the smell of lavender, therefore the oils must be safe for him. But I would come to the slightly different conclusion of The cat likes the smell of lavender, so lavender flowers (not necessarily oils) are probably safe for him. Sure, the essential oil smells just like a safe natural flower, but it’s not a safe natural flower in this case– it’s a concentration that is 500 – 2000 times stronger than a flower. Does that cat know this?
- What about the long-term weakening of liver and immune system? The post says “Melissa has been using essential oils in her practice for about three years now…” The article says that Dr. Melissa reviewed her cat’s blood work repeatedly at first to make sure there were no ill effects. That is most the convincing part of the whole article. But, is 1 -3 years long enough to see long-term weakening of liver and immune system? I’m not sure.
- Damage “does happen.” The article clearly says, “Shelton has spoken directly to people with cats that have been damaged by essential oils, so it does happen – just not as often as many people think.” It’s very easy to miss this line in the article.
As for me, if “it does happen,” that’s reason for some alarm.
But, I honestly think we’re getting into an area of cat and plant biochemistry where we don’t have all the details yet, so I personally will continue to err on the side of caution.
Sure, a vet knows a lot more about cat health than a concerned cat lover like me, but vets (like some MD’s) have been wrong before – and what do we do when they contradict each other?
We make our best guess and we choose the way forward we can live with. That’s all we can do.