By Lauren Baker, DVM
A brief survey of my bathroom and kitchen cabinets turned up 7 products containing essential oils – including shampoo, conditioner, 100% lavender oil, and an all-purpose natural spray cleaner. Do you use essential oils in the house? Do you know which kinds of essential oils are potentially toxic to pets?
Plant essential oils are volatile, organic (meaning carbon containing) compounds that contribute to plant fragrance, taste, and in some cases, plant self-defense against pathogens and predators. They can be extracted from plants through a few methods including steam distillation and cold pressing. Essential oils are now common ingredients in bath and skin care products, liquid potpourri, scent oils, flavorings, herbal medications, cleaning products, and pet shampoos. Essential oils that may be safe for human use are not necessarily safe for cats and dogs and other household pets due to differences in pet metabolism. There seems to be a growing belief that any “natural” products must automatically be safer than manufactured products. While in some cases this may be true, it is not always true, and there are many cases of pets being harmed by “natural” products such as undiluted tea tree oil. The most common sources of toxic exposure come from direct application of undiluted essential oils, or through accidental exposure to liquid potpourri (such as if a pet stepped in spilled liquid potpourri or drank from a potpourri pot).
Some of the most toxic essential oils are pennyroyal oil, citrus oil, oil of wintergreen, melaleuca oil (tea tree oil), pine oil, and eucalyptus. Liquid potpourri may also contain detergents that can be very caustic and cause significant gastrointestinal upset and/or be corrosive to the skin. Some concentrated oils like peppermint or cinnamon can cause skin irritation when applied in an undiluted manner.
One of the more common essential oil toxicities in dogs is Tea Tree Oil (TTO) toxicosis. TTO is produced from the leaves of the Melaleuca alternifolia tree. TTO is a complex mixture of around 100 different components, 50-60% of which are a type of compound called terpenes. Terpenes are extensively metabolized by the liver. Tea tree oil has been widely used by people for a variety of skin and respiratory disorders, for aromatherapy, and as an antiseptic, fungicide and skin care agent. In animals, TTO has been marketed as an animal shampoo, antiseptic, anti-allergy product, and anti-parasitic product.
Most cases of toxicity result after owners apply undiluted (100%) TTO to the skin in an attempt to treat skin lesions or repel fleas and ticks. TTO is sometimes seen as an ingredient in pet shampoos, but in these formulations, the percentage of TTO is usually less than 1%. It is not within the scope of this article to review the safety of every pet shampoo on the market. Most are likely safe, as the TTO and other essential oils are used in trace amounts. However, use common sense when purchasing shampoos. Stick with reputable brands, and avoid homemade formulations such as you might find on-line or at farmer’s markets.
Symptoms can result after the application of even a small amount of undiluted TTO. It can be absorbed through the skin, or the dog may lick it off. Symptoms can begin 1-8 hours after the time of application and can include central nervous system depression, unresponsiveness or coma, difficulty or inability to walk, shaking or tremoring. If the symptoms are mild, you can bathe the area on the skin where TTO was applied before seeking emergency veterinary care. However if the symptoms are severe, do not take time to bathe your dog, and seek immediate emergency veterinary care.
The veterinarian will assess your dog, and then work to stabilize him/her. This may include bathing if this has not been done and if the exposure was due to skin application, checking blood work to assess for liver injury, beginning liver protectant medications if there is evidence of liver injury, giving activated charcoal if your dog’s mentation is still normal to bind remaining toxins in the system, and likely will include other supportive treatments like intravenous fluids to maintain hydration and blood pressure. In severe cases of central nervous system depression, intubation and mechanical ventilation may be needed.
Because cats have a different liver metabolism than people and dogs, they may be at greater risk for certain toxicities. Essential oils that can be toxic in cats include sweet birch oil, oil of wintergreen, citrus oil (d-limonene), pine oil, eucalyptus oil, tea tree oil, Ylang Ylang oil, cinnamon oil, peppermint oil, pennyroyal oil, and clove oil. The symptoms you may see can vary depending on what kind of and how much oil is applied or ingested.
Oil of wintergreen is broken down to methylsalicylate which cats have a harder time metabolizing further, and this by-product can lead to gastrointestinal problems.
Citrus oils may cause increased salivation, muscle tremors, ataxia, coma, and death. Tea tree oil application in cats may lead to hypothermia, ataxia, dehydration, agitation, trembling, and coma. Pennyroyal oil can lead to severe liver necrosis (death) and liver failure.
Cats are more likely than dogs to be exposed to liquid potpourri containers since these are commonly placed on tables or counter tops. Liquid potpourri ingestion can cause injuries to the oral mucous membranes, gastrointestinal tract and in cases of significant ingestion, can lead to death. Exposure to the skin or eyes can result in significant ulceration.
There are some memes circulating on Facebook and other on-line communities about cats dying from diffused essential oils, sometimes many years later. There is no evidence to support these claims. However cats can be sensitive to changes in air quality, especially if the cat has a respiratory condition (such as asthma), so it is possible essential oil diffusers could lead to an increase in coughing, or even respiratory distress. Cats (and dogs) also have very sensitive noses, and may not appreciate essential oil fragrances in the house.
Treatment of essential oil toxicity in cats is generally based on the symptoms noted, and it can include blood work monitoring, liver-protectant medications, intravenous fluids, pain medications if there have been chemical burns, medications to protect the GI tract, and supportive care such as feeding tubes if the oral mucous membranes have been damaged, intubation and ventilation if there is severe central nervous system depression.
Birds can be very sensitive to aerosolized particles, so it is recommended to not use oil diffusers, fragrance sprays, scented candles, or Teflon-covered pans (fumes from the pan can be fatal). Toxicology data pertaining specifically to essential oil use in pet birds is scarce, but since it is well known that aerosols can be harmful to birds, it is best to avoid any sort of diffusers around your bird as well as application of undiluted essential oils to your bird.
Essential oils are pretty ubiquitous now. Both diluted products (pet and people shampoos, household cleaners, etc.) and 100% essential oil products are readily available online and in stores. While using products around the house with low concentrations of essential oils (under 1%) is likely fine in most cases, never apply undiluted or minimally diluted essential oils to your pets, or leave them around (such a liquid potpourri) where they could be accidentally ingested. Essential oil diffusers are likely less risky to use, but they could spill, or the scent could annoy your pet and/or irritate their airways. If accidental undiluted essential oil ingestion or application occurs, you will need to take action. If your pet is not showing symptoms, you can bathe your pet with dish soap to remove the oil, and either take your pet to a veterinary clinic for evaluation or call a pet poison control center (Pet Poison Helpline 855-764-7661 or ASPCA Poison Control 888-426-4435). If symptoms are very mild, you could quickly bathe your pet before immediately going to a veterinarian. If there are severe symptoms, however, seek emergency veterinary care immediately.
- Osweiler, Gary, et al. Small Animal Toxicology. Wiley-Blackwell, 2011