* Oils to avoid topically (applied directly to a part of the body) and internally with Cats: Basil, Citrus Oils (Bergamot, Grapefruit, Lime, Orange, Tangerine), Birch, Cinnamon, Clove, Dill, Fennel, Jasmine, Lavender, Melaleuca (Tea Tree), Oregano, Peppermint, Thyme, Rosemary, Spearmint, and Wintergreen.
* Oils to avoid topically and internally with Dogs: Birch, Melaleuca (Tea Tree),Wintergreen, Oregano, Cassia, Cinnamon, Clove, Rosemary, and Thyme.
* Oils to Avoid with some Small Animals: Melaleuca (Tea Tree), Cinnamon, Clove, Rosemary, and Thyme.
* Use additional caution when using Oils high in Phenols such as Basil, Anise, Clove, Oregano, Thyme, Cinnamon, or Cassia, especially around Cats, Reptiles, and Birds.
* Some Oils high in Monoterpenes may cause harm to Cats. Tea Tree is likely the most well-known, and Limonene have also been implicated. Some Pet owners should use caution with Citrus Oils, Pine, Spruce, Celery Seed, and Fir.
* Ketones accumulate in Cats increasing the risk of Ketoacidosis. Pet owners should use caution with Dill, Peppermint, Rosemary and Fennel.