While most flowers are completely harmless around pets, there are a few flowers that are extremely toxic to cats and dogs. So, if the person you are sending flowers to has cats or dogs, you should try to avoid the following: Amaryllis, Chrysanthemums, Delphiniums, Gladioli, Irises, Lilies, Peonies, and Tulips. If you're not sure, check the ASPCA website before ordering.