For example, Aspirin is a useful painkiller in humans and well tolerated by most people, but it is highly toxic to cats. Since tea Tree oil can penetrate the skin and be ingested when a cat self-grooms, there is a possibility of it accumulating in the cat's liver and building up to toxic levels. The UK distributors' leaflet presented only favourable information. It did not address the toxicity problem of Tea Tree oil or list the contra-indications if it is used. This is a case of irresponsible marketing and may already have led to 'mystery poisonings' or even deaths in cats and kittens.
Herbal remedies contain a variety of oils, a number of which are dangerous to cats.
Problems commonly occur when an oil safe for use on humans or dogs are used on cats. Incorrect usage of an oil is almost guaranteed to cause problems. Tea Tree oil is currently a fashionable remedy. Essential oils which contain phenols are particularly toxic to cats and cause liver damage. These include Oregano, Thyme, Eucalyptus, Clove, Cinnamon, Bay Leaf, Parsley and Savory Essential oils which contain ketones cause neurological symptoms.