Here is what I know about pets and plant poisoning - it depends on the animal how toxic a plant will be just like with people some are \"allergic\" to plants like euphorbia and some people have no reaction at all. So some cats and dogs may find Mandevilla toxic and some have no reaction at all. The good news is that almost all plants including mandevilla will cause your cat to vomit before it causes permanent damage. So your pet may take a taste, throw up and learn a lesson the hard way. If you are still concerned sprinkle some red pepper flakes near the plant to make it less palatable. Keep growing, Marianne Binetti