Paws for Thought: Smelling the Roses

Heed caution with kitty when using essential oils.

EDITOR’S NOTE: Dr. Janice Mitchell is a veterinarian at Island Animal Hospital and Little Current Veterinary Services, and a beekeeper too!

Smelling the Roses

by Dr. Janice Mitchell

Definition of aromatherapy: The use of aromatic plant extracts and essential oils for healing and cosmetic purposes. With the rise of companies such as DoTerra and Young Living, essential oils seem to be one of the biggest trends at the moment. Heck, I love to put a little dab of peppermint oil on the back of my neck in the morning before I go to work, and I know my colleague loves the smell of eucalyptus and birch oil. So, it was the other day when our technician showed me a veterinary site that specialized in essential oils that I realized that we veterinarians still do not know the full ‘scent’ of the matter. And thus, to the veterinary peer-reviewed sites I went to sniff out the truth. 

What are essential oils? Essential oils are extracts of plants that contain a large amount of volatile (easily evaporating) oil. They are extracted and concentrated by distillation or cold pressing. The smell and taste of plants are often determined by the essential oils they contain and are called “essential” as they were thought to represent the very essence of odour and flavour.

Aromatherapy has two main routes of activity, one of which is pharmacologic—volatile molecules are absorbed through the nasal and respiratory mucosa and thus detected systemically. The other is behavioural, where ambient molecules trigger olfactory (smell) receptors to directly stimulate a chemical messenger release in areas of the brain to cause some physiologic change. In addition, a smell can trigger a memory. As an example, the memories people associate with lavender (like Grandma’s attic) are likely completely different from any memories a cat may or may not associate with lavender.

Information about essential oil health and safety effects are sparse and often contradictory. Asking, ‘Are essential oils safe?’ is similar to asking, ‘Is medicine safe?’ or, ‘Are plants safe?’ The type of oil, dose and route of exposure all determine the answer to this question. This is especially true when discussing their effects on cats.

Cats are much more susceptible than dogs to certain essential oil toxicities. Cats’ livers are deficient in a process called “glucuronidation,” an important step in the metabolism of many compounds. As such, chemicals that are metabolized by other species often accumulate or are broken down into toxic metabolites in cats. This is especially true for compounds called “phenols” which contain an “aromatic” or “benzene” ring. Many essential oils contain phenols and, as such, may be poisonous to cats. These may lead to liver failure, seizures or other serious issues. Cats’ small size means they are susceptible to poisoning by smaller volumes of oil and their tendency to groom themselves means skin contact often leads to oral contact. Cats also have a very sensitive respiratory tract, being prone to reactions to inhaled substances such as smoke and are thus more likely to develop respiratory distress when exposed to volatile oils. 

Exposure to essential oils may be oral, through inhalation, or even through direct absorption through the skin. Some essential oils can induce a reaction that is not directly “toxic” by triggering allergic reactions. Cats with asthma, chronic upper respiratory disease, skin allergies or other similar conditions may experience an exacerbation of clinical signs when exposed to essential oils. In the case of asthma, these reactions can be serious or even fatal. Cats can also develop watery, irritated eyes and noses from chemical irritation of the respiratory or eye lining membranes, or develop dermatitis from direct skin contact. Other oils may be more directly toxic, causing failure of the liver, kidneys, heart or other organs.

I noticed while researching that the lists of toxic essential oils varied from one source to another. These lists have limited use because potential toxicity depends on the route, rate, amount of exposure, species, as well as the supplier quality and the other compounds that are in the preparation of a brand of oil. There is also a shortage of published scientific studies. Thus, these lists are not very accurate. However, I will quote two lists from one reputable veterinary site ( Oils to avoid topically and internally with cats: Basil, citrus oils (bergamot, grapefruit, lemon, lime, orange, tangerine), birch, cinnamon, clove, dill, fennel, melaleuca (tea tree), oregano, peppermint, thyme, rosemary, spearmint and wintergreen. Oils to avoid topically and internally with dogs: birch, melaleuca (tea tree) and wintergreen. Use caution with hot oils such as oregano, cassia, cinnamon, clove, rosemary and thyme.

Some other general guidelines to the use of essential oils include: Only use therapeutic grade essential oils, not from Amazon or your local grocery store; do not use oils on or near eyes, ears, nose or genitals of your pet; use a water diffuser for aromatic use and allow your pet to roam freely with an open door to the room; dilute for topical use; avoid the use of essential oils in households with cats with asthma, allergies or similar conditions; never apply essential oils directly to cats or feed oils to cats; and caution should be used around animals that are pregnant, nursing, young, or on certain medications.

If you suspect exposure to a noxious essential oil, take your pet, along with the product packaging, to a veterinarian immediately. Do not try first aid such as induction of vomiting or giving home charcoal therapy. If a cat gets essential oil on its paws or fur (e.g., spilled diffuser or bottled essential oil), wash it off with bland soap and water, rinse well, and call your veterinarian right away for further advice.

Until next time, I leave you with a science fact: Dogs have 300 million olfactory receptors, cats have 200 million olfactory receptors and humans have six million (who counts these anyway?). Happy smelling!