Always pay attention to how your animals react to essential oils and start with minute amounts.
Some essential oils need to be diluted before being used on animals. Others should be avoided altogether because they have constituents that are overpowering or counterproductive to the animal.
Then again, many times it’s not the essential oil that is the problem, but the additives, thinners and other added ingredients that the animal can react to. That’s why its so important to use Therapeutic grade essential oils, like you’ll find on this site.
In the interest of “Better to be safe than sorry,” I’m posting this list of essential oils to avoid with animals from Aromatherapist, Kristen Leigh Bell:
Anise Birch Bitter Almond Boldo Calamus Camphor Cassia Chenopodium Clove Leaf and Bud Crested Lavender Garlic Goosefoot Horseradish Hyssop (use decumbens variety only) Juniper (use j.berry only)
Mugwort Mustard Oregano Pennyroyal Red or White Thyme Rue Santalina Sassafras Savory Tansy Terebinth Thuja Wintergreen Wormwood Yarrow
Source: Holistic Aromatherapy for Animals by Kristen Leigh Bell. Kristen Leigh is a master aromatherapist certified by the Pacific Institute of Aromatherapy who studied with Dr. Kurt Schnaubelt*.
*Kurt Schnaubelt earned his Ph.D. in Germany from Technical University of Munich. A leader in aromatherapy in the United States since 1983, he is the author of Advanced Aromatherapy, a textbook on scientifically based aromatherapy originally published in Cologne in 1995.
Again, this is from one source and I’m not saying this is gospel. Use your own judgment with your animals. They may or may not have a problem with some of the essential oils listed when they are therapeutic-grade.