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Plants Poisonous to Pets

Pet Tales

by Barry B. Burtis D.V.M.

Plants Poisonous to Pets

For many, the pleasures of gardening return with springtime. Gardeners, if also pet owners, should be aware of the threat some plants may pose to the health of their pet. There are some general points to remember, as this topic is discussed. A poisonous plant is one that contains substances that even in relatively small quantities can cause illness or death. Different parts of the plant may be toxic - leaves, stems, fruits, seeds, roots or even the whole plant. Some plants are more toxic when they are young, others when they are mature. Accessibility and palatability of plants may influence the risk of them poisoning a pet. Added to these variables, there are animal-related factors that may influence the danger of plants. Puppies and kittens are more likely to ingest or mouth plants than adult animals. However, adult animals, especially if they are bored or have certain behaviour abnormalities, also may eat plants. Caged or penned animals may have increased risk of sampling plant material. Animals that get into garbage or are fed leftovers have an increased risk of being exposed to plant poisons. Even pet birds, confined to the house, may be poisoned from ingestion of the leaves, seeds or blossoms of certain house plants.  Finally, although there may be some overlap of body systems affected in a pet poisoned by plants, most often the plant toxin will affect one system primarily. 

With these comments in mind, I thought it might be helpful to list some of the plants familiar in our area that could cause problems for pets.

In my experience, the gastro-intestinal system of pets is the most likely area to be affected by plant poisoning. Here are possible offenders: the bulbs, primarily, of a number of plants - crocus, daffodils, tulips, yellow iris, purple flag iris and star-of-Bethlehem; all parts, but especially the seeds of castor beans, poinsettias and rhododendrons; seeds of Chinese or Japanese wisteria, holly and English ivy; any green growth and sprouts and most top parts of the potato; all parts but especially berries of common privet; the tuberous vines or sap of cyclamen; all parts of azalea and hydrangea. Symptoms that might be noticed in an affected pet include nausea, vomiting, diarrhea, abdominal pain, fever and loss of appetite.

Neurological signs such as excitement or depression, trembling or even convulsions and coma can occur with the ingestion of certain plant toxins. The following plants may be a source of such toxins: the same plant parts listed above of castor bean, cyclamen, holly, English ivy, star-of-Bethlehem, tulip, yellow iris; berries, stem and sap of the poppy; foliage and seeds of the sweet pea; foliage, bark and seeds of yew (Taxus sp.);  Morning Glory seeds.

Lily of the valley seems particularly to affect cats, where ingestion of the whole plant but especially the bulbs, can cause increased thirst and urination as the earliest signs of the kidney damage it can cause.

Increased salivation, pawing at the throat or mouth area, difficulty swallowing or even breathing problems can result from ingesting plants that irritate the mouth or throat. The leaf, stem and stalk of dieffenbachia or the leaves of  rhubarb can do this to our pets.

Some plants can be dangerous because they can affect heart function. The leaves, berries, stem and sap of euonymus, all parts of oleander, foliage, bark and seeds of yew, crocus bulbs, the flowers and seeds of larkspur, aforementioned parts of potato and lily of the valley can cause cardiac changes. Increased rates and irregularities of the heart beat possibly leading to shock and collapse can occur. Poisoning with these plants can cause gastro-intestinal and neurological signs also. Fresh, cooked or dehydrated onions can cause one type of anemia in dogs. Most commonly small dogs are affected but there is one report of such an anemia in two cats fed onion soup.

Also, it should be remembered that apricot pits and peach and plum seeds are cyanide producers and hence may threaten a pet's health.

Plan your garden and your pet's access to the garden carefully. This will allow full enjoyment of both plants and animals in your home and yards.