teatree, being an Australian native, is quite possibly not good for cats as it evolved on a continent that did not have a cat population until our mob arrived there. Is is a strong antiseptice and really good all-round thing to have in the medicine cabinet, but I would use it with caution around cats and dogs (which did not arrive in OZ until around 5000 years ago). So, my advice?? for what it's worth, keep clear of topical or internal applications because kitties being kitties, topical=internal