WARNING!!! Tea tree oil is *highly toxic* to a cat's liver and should NEVER be used on them or around them--not even in an air diffuser that they could breath in. Just because one person used this without an adverse incident does not mean it is safe. Certain other essential oils are also toxic (others may be safe), and most safe ones need a nontoxic carrier oil (do not use undiluted). Always do your homework before considering any type if essential oil!