Many plant intoxications require that the plant be ingested, usually from chewing on leaves or other plant parts, but sometimes just touching the plant or its sap residue on other objects can bring about symptoms of poisoning, such as with poison ivy. An interesting point is that while dogs are generally resistant to the irritant effect of poison ivy, they can get the sap on their coats and then transfer it to a human, causing a rash on the human when they never got close to the plant.

Another point to consider is that although plants can be loosely grouped into categories of "generally nontoxic," "mildly toxic" and "very toxic," the signs that are seen will depend on the size of the patient and the amount consumed.

I've found a couple of good reference sites on the Internet that have lists of toxic and nontoxic plants. The Minnesota Poison Control System maintains one. It lists plants with different levels of toxicity and gives additional information about avoidance of intoxication and first aid for intoxication, both for people and pets. The Web address is http://www.mnpoison.org/index.asp?pageID=116. The home page for this site contains good information about all types of poisoning topics.

Another good site is the one maintained by the University of Illinois at Urbana-Champaign. This site has pictures of many toxic plants to aid in their identification. Its address is http://www.library.uiuc.edu/vex/toxic/comlist.htm.

Another related topic for consideration at this time is the chemicals that are used for lawn and plant care, such as fertilizers and insecticides. Be sure to read and follow label directions carefully with these products. In general, if you apply liquids or granular products that are watered in, the lawn should be dry before animals are allowed on it. Anything that is produced as bait for insects to consume may also be appetizing to dogs and cats, so caution is needed when using these products, too.