All "ivy" are not ivy. Scientifically speaking, ivy consists of 15 plants from the genus Hedera. Of these 15 plants, only English ivy (Hedera helix) is included in the American Society for the Prevention of Cruelty to Animals' (ASPCA) database as being toxic to cats. The other 14 are not listed in the database at all (as either toxic or nontoxic). However, many other "ivy" plants, or ones that are called ivy but not part of the Hedera genus, are included. Some of these plants are toxic while others are not.
Toxic ivy plants include English ivy (Hedera helix); iris ivy (Helix hibernica); Australian ivy palm (Schefflera or Brassaia actinophylla); mountain ivy or ivy bush (Kalmia latifolia); Boston ivy (Parthenocissus tricuspidata); cape, parlor or German ivy (Senecio mikanioides); ground ivy (Glechoma hederacea); and devil's ivy or ivy arum (Epipremnum aureum).
Non-toxic ivy plants include grape ivy (Cissus rhombifolia); Kenilworth or coliseum ivy (Cymbalaria muralis); ivy peperomia or ivy leaf peperomia (Peperomia griseoargentea); poison ivy (Toxicodendron species); spider ivy (Anthericum or Chlorophytum comosum); and Swedish ivy (Pilea nummulariifolia or Plectranthus australis).
Hedera helix is a common house and landscape plant. It is also featured on ASPCA's list of the 17 most common poisonous plants. It is known by many names, including branching ivy, English ivy, glacier ivy, needlepoint ivy, sweetheart ivy, California ivy and Hahn's self branching English ivy. Hundreds of cultivars of it exist, but all are evergreen and produce berry-like fruit known as drupe. It contains triterpenoid saponins, which causes vomiting, abdominal pain, diarrhea and hypersalivation if ingested.
If you suspect your cat has ingested a poisonous ivy plant, you need to act immediately even if he is not showing any signs of illness. Call your veterinarian or the ASPCA Animal Poison Control Center hotline at (888) 426-4435. Depending on the situation, your cat may or may not need to be taken to a local clinic immediately.
Poison ivy (Toxicodendron species) is non-toxic to cats, according to the ASPCA. Cats also do not usually suffer from the contact dermatitis, or inflammation of the skin, that poison ivy is known for. Despite this, it is often included on lists of plants poisonous to cats and dogs.
Having a cat does not mean you cannot have house plants, but that you will need to train your cat not to eat them. Start by providing your cat with her own "cat plant" that she can munch on, such as catnip or special cat grass. Next, purchase a plant that is nontoxic to cats. Paint the underside of the leaves with a hot chili oil and spray the top of the leaves with a 1 percent perfume solution (1 part perfume to 100 parts water). Place the plant in a location where your cat will have easy access to it. Recoat the leaves daily. Once you cat has gotten a nibble, she should learn to leave it alone. Wait until your cat leaves the safe houseplant alone before bringing in other plants. Spray these plants with the perfume solution to encourage your cat to stay away from them, but you can discontinue the hot sauce once your cat has learned her lesson.