PLANTS

It is difficult to give concise information about plant toxicities as there are hundreds of plants that are potentially poisonous to animals. However, actual reports of animals getting seriously ill from eating plants are relatively infrequent compared to reports of poisonings from household products or drugs. The plants discussed below can be found in Minnesota and represent among the most dangerous of poisonous plants. You may notice the conspicuous lack of "holiday plants" among the list. While many people seem to think poinsettias, ivy and mistletoe are dangerous plants, and while these plants have toxic potential, they seldom cause serious clinical signs if eaten.

It is worth noting here that dogs and cats often vomit after chewing on plants; this probably does not represent "poisoning" or any dangerous exposure. Only severe or persistent vomiting is a danger sign in small animals. Sporadic vomiting without accompanying signs of illness (for instance, diarrhea, depression, loss of appetite) is rarely a cause for worry, whether associated with plant ingestion or not. The best advice, however, is to contact your veterinarian if you have specific concerns.

JAPANESE YEW - XXX

Scientific Name — Taxus cuspidus
Common names — Yew, Spreading English Yew, Canada Yew
Plant with similar toxicity: Zygadenus nuttzii, common name Deathcamas.

The Yew plant is an ornamental yard plant, most often used in landscaping around the foundation of a house. It is an extremely poisonous plant and the animal needs to eat only one-tenth of one percent of its body weight to get a toxic dose. (For example, a 50 pound dog would need only .05 pounds or less than 2 ounces of the plant to get a potentially fatal dose!)

The toxin in the Yew is an alkaloid and works by depressing electrical activity in the heart. Signs may include sudden death from heart failure. If the animal shows clinical signs of toxicosis other than sudden death those could include: trembling, incoordination, diarrhea, and collapse.

We rarely recognize clinical cases of Japanese Yew poisoning in animals at the University, although that may be partly because of the difficulty in proving the presence of the toxin as well as the great toxicity. In cases where animals are found dead it is very difficult to prove the Yew caused the death unless the animal is necropsied (a veterinary term for an autopsy) and evidence of ingestion - evidence that the animal actually ate the plant — is found. There are no specific blood or chemical tests to determine if Yew toxicity is present. While Yew poisoning does not seem to be very common, the best advice is to know what ornamental plants are present around your house and other buildings and to make sure the Yew is not one of them!

ARACEAE FAMILY - X

Scientific name — Many, including: Schefflera actinophylla, Dieffenbachia maculata, Begonia tuberhybrida, Philodendron
Common names — Starleaf, Tuftroot, tuberous begonia, wax begonia, water plant, yellow calla, peace lily, etc.

This family of house plants and ornamentals contains oxalates and causes toxicity by the formation of calcium oxalate crystals in the animals organs and by causing the release of chemicals in the body which can cause an acute allergic reaction. Signs may include excessive salivation, head shaking, pawing at the mouth, difficult breathing, vomiting, and diarrhea.

Fortunately, the plant causes pain and irritation on chewing and therefore animals rarely eat it in sufficient quantities to cause severe damage. Much of the motivation for chewing on such a plant involves boredom and other psychological factors (recent changes in the household, etc.) so it may be worth noting if an animal begins suddenly eating house plants they used to ignore and discussing the subject in a phone call or visit to your veterinarian. If your household plants include any of those in the Araceae family, be aware of the potential for toxicity and preferably keep the plants away from the pet or switch to safer house plants.

RHODODENDRONS (and other cardiac glycoside containing plants) - X

Scientific name — Many, including: Rhododendron, Nerium oleander, Digitalis purpura.
Common names — Rhododendrons, milkweeds, lily-of-the-valley, laurel, oleander, azalea, foxglove, etc.

This group of common plants all contain cardiac glycosides. Cardiac glycoside drugs derived from one of these plants, digitalis (foxglove), have been used for many years in the treatment of heart disease in people and animals. Due to their actions on the heart, however, ingestion of plants containing glycosides can be fatal. Signs may include vomiting, diarrhea, collapse, or death from heart failure. Fortunately, the plant has a bitter and very unpleasant taste! Nonetheless, the American Association of Poison Control Centers (AAPCC) report covering 425 fatal animal poisonings in 1990 includes 4 resulting from cardiac glycoside-containing plants.

NIGHTSHADES/Solanums - X

Scientific name — Many, including: Solanum dulcamara, Solanum nigrum, Physalis.
Common names — Nightshades, Chinese lantern, Christmas cherry, Ornamental pepper

These primarily ornamental plants contain toxins called solanines that affect either the stomach or the brain, depending on the type of poison contained in the plant. It should be noted that some plants contain no poison whatsoever and it is impossible to be certain whether a given plant contains the poisonous substances. Clinical signs of toxicity for the plants containing the stomach poison include severe gastrointestinal upset, such as vomiting, diarrhea (possibly bloody), abdominal pain. If the toxin affecting the brain is present in the plant eaten, signs may include drowsiness, salivation, difficult breathing, trembling, weakness and collapse. The AAPCC report indicated 2 of 425 fatal poisonings occurred as a result of poisoning by solanines.

Additional information concerning common small animal poisons can be gained through the following links:

Drugs
Household Products
Miscellaneous

SUMMARY: Hopefully you have found this guide interesting and useful. The underlying message in any discussion of poisons is to avoid poisoning wherever possible by careful packaging, storing and appropriate use of potentially toxic items. A second important concept is to recognize potential poisoning as soon as possible, ascertain what it was the animal was exposed to and get help. Whereas poisoning is not the most common of problems that most pet owners face with their companion animals (thankfully!), if such a situation should arise it is worth having considered the possibility beforehand. Having some guidelines on how to proceed can provide the pet the best chance to be treated and recover from the crisis. Even more importantly, it is worth having considered the risks and eliminated them before those risks become reality.

ACKNOWLEDGEMENT: This guide was generously prepared by Julie Dahlke, DVM, a graduate of the University of Minnesota, College of Veterinary Medicine. She compiled information on poisons which are commonly accessible to pets and which cause their owners great concern. This is not an exhaustive guide to companion animal poisons but instead a useful, readable reference designed for the pet owner. Dr. Dahlke thanks Dr. Mike Murphy, a veterinary toxicologist and Ms. Lynn Lawrence, both of the University of Minnesota for their assistance in the development of this guide.

For more information on poisonous plants, read, Poisonous Plants of the United States and Canada. John M. Kingsbury, Prentice-Hall or any of a variety of books on regional plants at your local book store.