According to the Pet Poison Helpline the most common essential oil toxicities seen are to Melaleuca or Tea Tree Oil, Pennyroyal, Oil of Wintergreen, and Pine Oils.
Also known as tea tree oil, is our most common essential oil offender in toxicities to dogs. Tea tree oil originates from the leaves of the Australian tea tree. These exposures often occur with application or administration of the concentrated tea tree-oil by well-meaning pet owners attempting to treat their pet for various skin conditions or external parasites such as fleas. It is equally absorbed with both dermal or oral administration and both result in toxicity.
An oil from Mentha Pulegium, more commonly known as European Pennyroyal or squaw mint. Pennyroyal has a long history in folk medicine with use as an insect repellent. It can be used by unsuspecting pet owners to treat flea infestations or to try to prevent flea infestations. Oral or dermal exposures can both result in toxicity. The short answer on the toxicity with pennyroyal is that it causes hepatic necrosis or liver failure.
Oil of Wintergreen
It is derived from the Gaultheria Procumbens or the Eastern Teaberry. Oil of Wintergreen contains methyl salicylates, more commonly know as aspirin. It is many times used topically as a pain reliever for muscle aches and pains but may also be used in holiday candies with bakers having bottle of concentrated product. Dogs can show signs of aspirin toxicity and we can see signs of vomiting due to severe gastrointestinal upset and ulcers, along with potential renal and liver failure.
Derived from Pinus sylvestris or the Scots Pine located in Europe. Pine oils are used as a natural disinfectant, deodorizer, household cleaning products and massage oils. The touted benefits of pine oil include increasing circulation, aids in decreasing swelling, tenderness and pain in sore joints and muscles along with antibacterial properties. What we can see in dogs with dermal or oral exposure can be dermal or gastrointestinal irritation, vomiting that may be bloody, drooling, weakness, ataxia, along with affects to the central nervous system, and potential renal and liver affects.
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.
Essential oils that are known to cause poisoning in cats include:
Oil of wintergreen, oil of sweet birch, citrus oil (d-limonene), pine oils, Ylang Ylang oil, peppermint oil, cinnamon oil, pennyroyal oil, clove oil, eucalyptus oil, and tea tree oil.
Symptoms that develop:
Depend on the type of oil involved in the exposure and can include drooling, vomiting, tremors, ataxia (wobbliness), respiratory distress, low heart rate, low body temperature, and liver failure.
Inhalation of strong odors or fragrances can cause some cats to develop a watery nose or eyes, a burning sensation in the nose/throat, nausea leading to drooling and/or vomiting, and difficulty breathing. Difficulty breathing in a cat is evidenced by labored breathing, fast breathing, panting, coughing, or wheezing.