Hi All, The part of the Aloe that is toxic is the Latex layer beneath the skin. This is NOT the part used for commercial Aloe preparations/gels. So as long as you don't cut open an Aloe leaf and rub it on your cat, it is okay to use the gel. As always, check the labels and try not to use a formula loaded with preservatives.
Tea Tree Oil - however - is a NO NO for Cats!! Cats cannot metabolize the oils like dogs and humans can, and it ends up harming the liver. Even Cat Fancy has run articles warning against using most essential oils on Cats. Kat (Mew Jersey)
