Some quite strong feelings and opinions have been expressed about essential oils and cats, and a frequently asked question is “Is it safe to diffuse essential oils around cats?”. Diffusing essential oils can be toxic to humans if it’s over-done, causing neurological symptoms such as headache or fatigue. In general, making long lists of specific oils that are allegedly “safe” or “toxic” to cats doesn’t make a lot of sense to me – it’s more about overall exposure. You can diffuse essential oils around cats safely, so long as there’s good ventilation, you only diffuse small amounts for limited periods of time, and your cat has the freedom to leave the room if it wants. A few parts per million of aromatic vapor in the air is not likely to be harmful, but be careful to avoid build-up of vapors over many hours.
Cats almost completely lack important liver enzymes that humans do possess, and which are important in the metabolism of many essential oil constituents. These are primarily UDP-glucuronosyltransferase (UGT) enzymes such as UGT1A6, UGT1A9 and UGT2B7 (Court 2013, Van Beusekom 2013). Therefore, there is a theoretical risk of increased toxicity to cats, though this is very much less of an issue with dogs. Menthol, for example, is primarily metabolized (in humans and rodents) through glucuronidation, and toxicity testing shows that menthol is 3-4 times more toxic to a cat than a rat (Opdyke 1976). We don’t know for sure that the greater toxicity to felines is because of the missing enzyme, but it’s very likely. But, while 3-4 times is a significant difference, it’s not a massive one. I certainly don’t advocate dousing your cat in large quantities of neat essential oils – ever. And cats are quite susceptible to toxicity from nutmeg oil and tea tree oil. But, a small amount of any essential oil, and a moderate amount of most, will not harm your cat.
In 1995 a Japanese film crew came to my house in Brighton England, to film me and my cat Myrtle. It was for a Japanese tv show about famous people and their cats, but the focus was clearly on Myrtle, not me. And, I guess you did not have to be an A-list celeb to be classed as “famous”… The shoot with Myrtle was difficult. She was not a very social creature even with her family and there were strangers in the house. At one point she hid under a bed, and my two (then little) girls decided to jump up and down on the bed, to “encourage” her to come out. The film crew’s focus went down to floor level in order to film Myrtle steadfastly staying where she was, with the mattress bouncing up and down on her head. This went on for some time.
Somehow Myrtle survived a further 13 years and when she passed away she was replaced by Ziggy. Ziggy is a Maine Coon, a breed of cat ideally suited to cold climates. Maine Coons have long hair, even between their toes, and long, bushy tails. So, not exactly perfect for Southern California weather, but when we got him as a kitten he didn’t look especially hairy! I have never used essential oils on Ziggy, because I have never had a reason to. I did use tea tree oil on Myrtle once, when she had an infected puncture wound. I squeezed out the pus, and dripped one drop of tea tree oil into the hole. I repeated this treatment over next two days, and she healed up fine after that.