Department of Animal Science - Plants Poisonous to Livestock

BRIEF: Could you help me find some information on plants poisonous to dogs?


QUESTION:
I've been asked to write an article regarding poisonous plants for our Pekingese lover's newsletter.

ANSWER:
Dogs are not as frequently poisoned by plants as are livestock. When dogs are poisoned, it is usually with made-made chemicals, either as a result of veterinary treatment gone wrong or substances found by the dog itself. The most common poisonings are due to insecticides (e.g.flea treatments) and worm medicines. These are pretty hazardous materials and if used incorrectly can be lethal. The next most common poisoning is by the various rat poisons, be they warfarin or strychnine based. The vitamin D based rodenticides are safer around dogs, because they are unlikely to hurt the dogs unless they make a steady diet of them. Unfortunately, it takes a bit longer to kill the rats, too. Antifreeze, window washing fluid and other toxic liquids are the next most common way dogs poison themselves. Even Tylenol, Motrin, Aleve and aspirin are hazardous, especially to a small dog like a Pekinese. Chocolate is toxic to dogs as well, as you probably know, with an LD50 of 100-200mg/kg body weight. This is not usually too much of a worry for a big dog (a 88 pound dog would need at least 80 ounces of chocolate candy to kill itself and probably more), but a little dog... But you asked about poisonous plants! Yes, there are plants which are poisonous to dogs. Many houseplants and ornamentals (Philodendron, Dieffenbachia, Jack in the Pulpit, etc.) have painful microscopic needles in them that cause swelling and inflamation in the mouth and throat of dogs (or kids!) that chew on them. This is rarely fatal, and usually helps train the dog not to chew on plants. The very lethal plants tend to vary by location. In warmer climates, oleander poisoning can occur. This plant contains a potent digitalis-like heart poison - only a leaf or two will kill a dog, and reports exist of dogs dying from drinking water from bowls with wind-blown oleander leaves floating in them. I don't know how true those accounts are, but this plant is bad news. Foxglove would do the same thing. The yew bush (Taxus species) is a potential killer in the North East, too, but dogs are very much less likely to gnaw on it than others. Murray Fowler wrote a great book on this subject in the 80's that was published by Ralston Purina, but I can not find my copy. Perhaps you can find it in your library!