Your pet may have a passion for houseplants. One of my cats does and loves to nibble on the leaves every now and then.  Some common varieties of house plants can make your pet sick.  A few may even be deadly.  More than 240 types of house plants are considered to be a hazard to pets.  It all depends on what part of the plant that the pet eats. For example, the poisonous part of the Amaryllis is the bulb which can cause nausea, vomiting and even paralysis in pets. Other plants such as Crown of Thorn and Cacti only cause skin reactions. Poinsettias also irritate pets although the effects are not as bad as they are rumored to be. If your pet does ingest something that you think is poisonous, do not try to administer any pet medication but call the ASPCA Animal Poison Control Center at 888-4 ANIHELP charges may apply.