Essential oils for fleas and ticks? Not so fast
Most of the time we veterinarians think essential oils are harmless or, at worst, mildly noxious—but is that true? At a recent Fetch dvm360 conference, Tina Wismer, DVM, DABT, DABVT, medical director for the ASPCA Animal Poison Control Center in Urbana, Illinois, helped coach attendees on how to respond to clients who say they're using essential oils for flea control. Here's what she knows.
D-limonene is derived from orange pulp and has minimal to moderate efficacy to control fleas, Dr. Wismer says. If diluted properly, it has a high margin of safety; if not, it can cause dermatitis, oral irritation, lethargy, vomiting, salivation, ataxia and muscle tremors. This essential oil can penetrate the skin and cause peripheral vasodilation, leading to hypotension and hypothermia.
Melaleuca oil is an essential oil from the Australian tea tree, Melaleuca alternifolia. It does have antibacterial and antifungal properties at higher concentrations, but the products labeled for use in animals are 5% or less, and the efficacy of this agent to repel or kill fleas has not been established, Dr. Wismer says. Inappropriate application of Melaleuca products or products not intended for external use may result in ataxia, weakness, tremors and depression.
If your clients have been on Dr. Google, they may have read that pennyroyal oil is effective against fleas and ticks. This has not been proven, Dr. Wismer says—but toxicity definitely has. Pennyroyal oil, derived from the leaves and flowers of the pennyroyal plant (also called squaw mint or mosquito plant), contains a volatile compound called pulegone, which is responsible for the plant's toxic effects. If pennyroyal is applied directly to an animal it can cause depression, vomiting, hepatic necrosis, diarrhea, epistaxis, seizures and death. Pennyroyal oil should never be used on animals.
What to do if your patient is exposed
With essential oils, treatment consists of getting the oil off the animal and providing fluids and supportive care, Dr. Wismer says. Keep in mind that if the oils have been applied to irritated or broken skin, the risk of toxicosis is higher due to increased systemic absorption. Bathe the pet in liquid dishwashing detergent, and be aware that most essential oils have long half-lives (days) due to enterohepatic recirculation. Administer appropriate pain control as needed, and monitor liver values in cases of pennyroyal exposure.
Time for the soapbox
It's up to us as veterinary professionals to ask our clients about any essential oil usage on their pets and then counsel them accordingly. If you're reticent (like me) to have these conversations because you think it may damage your relationship with the client, remember this: Fleas and ticks are more than a nuisance. They carry and transmit debilitating and sometimes fatal diseases, some of which are zoonotic. You can tell them that leading experts in our field, like Richard Gerhold, DVM, MS, PhD, confirm that there is no support for the use of essential oils as parasite control.
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