Poisonous Plants

Laurie Anne Walden, DVM

Do you know which common plants are toxic to dogs and cats? Spring is just around the corner and Poison Prevention Week is the third week of March, so this is a good time to discuss plant hazards in the house and yard.
 
This article covers only a few of the plants that are dangerous to dogs and cats. For more complete lists, see these websites:

• Toxic and non-toxic plant database, ASPCA Animal Poison Control
• Poisons list, Pet Poison Helpline

 
If you think your pet may have licked or swallowed a plant or other toxic substance, contact your veterinarian or call one of the 24-hour animal poison control hotlines (a fee may apply):

• ASPCA Animal Poison Control, (888) 426-4435
• Pet Poison Helpline, (855) 764-7661

 
Azalea, rhododendron
All parts of these plants are toxic to pets. Ingestion can cause vomiting, diarrhea, muscle weakness, convulsions, coma, and death.
 
Crocus
Autumn crocus (Colchicum autumnale) and spring crocus (Crocus species) are 2 different types of plant. Autumn crocus is in the Liliaceae family. All parts of the autumn crocus are highly toxic to pets, even in small amounts. Ingestion can cause vomiting, bloody diarrhea, organ damage, shock, and death. Symptoms may not appear until a few days after ingestion.
 
Spring crocus is in the Iridaceae family. These plants are not particularly toxic, although dogs and cats that eat them can develop drooling, vomiting, and diarrhea.
 
Cyclamen
Cyclamen is a common flowering houseplant. The tubers (roots) are the most toxic part. Dogs and cats that eat any part of the plant can develop vomiting and diarrhea. Ingestion of large amounts can cause heart rhythm abnormalities, seizures, and death.
 
Daffodil, jonquil, paperwhite, amaryllis
Dogs and cats that eat bulbs of Narcissus species can develop vomiting, diarrhea, and belly pain. Ingestion of large quantities can lead to problems with breathing and heart rhythm.
 
Dieffenbachia
Dieffenbachia (dumbcane) contains substances that cause severe mouth and throat pain. Ingestion can also cause nausea and trouble swallowing.
 
Hyacinth, tulip
Ingestion of hyacinth (Hyacinthus species) or tulip bulbs can cause mouth irritation, vomiting, and diarrhea. Dogs that dig up the bulbs or find a bag of stored bulbs may eat large quantities and have more severe symptoms. Grape hyacinths are a different genus (Muscari) and are not toxic.
 
Iris
Ingestion of iris rhizomes (bulbs) can cause vomiting, diarrhea, drooling, and lethargy.
 
Kalanchoe
These flowering houseplants contain substances that cause stomach upset and, in higher doses, heart rhythm abnormalities and tremors.
 
Lily
Don’t bring lilies into your house if you have cats! Some are extremely dangerous for cats, even in small amounts. “True” lilies (Lilium and Hemerocallis species) contain a toxin that can cause fatal kidney failure in cats. Some examples are Easter lilies, Asiatic lilies, daylilies, stargazer lilies, and tiger lilies. All parts of these plants are poisonous to cats, and even pollen licked from a paw or water licked from a vase can be toxic. These lilies do not cause kidney failure in dogs.
 
If your cat ingests any part of a lily, seek veterinary care immediately (bring the plant with you for identification). For more information, see No Lilies for Kitties on the Pet Poison Helpline website.
 
Calla lilies, peace lilies, and Peruvian lilies (Alstroemeria) are not true lilies and do not contain the agent that causes kidney failure. However, ingestion can cause mouth irritation and stomach upset in both dogs and cats.
 
Lily of the valley
Lily of the valley (Convallaria majalis) contains toxins called cardiac glycosides, which cause serious heart rhythm abnormalities. Ingestion of lily of the valley may be fatal. Other symptoms are vomiting, painful abdomen, and diarrhea. Cardiac glycosides are also present in foxglove (Digitalis species), kalanchoe, milkweed, and oleander.
 
Marijuana
The Pet Poison Helpline reports a 448% increase in marijuana cases in pets in the past 6 years. Pets can be poisoned by eating food that contains marijuana, being exposed to smoke, or ingesting the plant itself. Marijuana poisoning can cause drooling, vomiting, diarrhea, stumbling, lethargy, incontinence, changes in heart rate, seizures, coma, and death in pets.
 
Oleander
All parts of the oleander plant contain cardiac glycosides. Oleander ingestion can cause heart rhythm problems, rapid heart rate, vomiting, diarrhea, and death.
 
Sago palm
Sago palm is extremely toxic to dogs and cats. It is also called fern palm or cycad (Cycas and Zamia species). This plant grows outdoors in warm regions and is also used as an ornamental houseplant. The seeds are the most poisonous part of the plant, but all parts contain the toxic agent. Ingestion causes liver failure, vomiting, diarrhea, abdominal pain, seizures, and death. According to the Pet Poison Helpline, only about half of animals that ingest sago palm survive. ASPCA Poison Control reports that ingestion of 1 or 2 seeds can be fatal.

Sources:
Brownie CF. Houseplants and ornamentals. Merck Veterinary Manual website. Accessed March 9, 2018.
Brownie CF. Range plants of temperate North America. Merck Veterinary Manual website. Accessed March 9, 2018.
Poisonous plants. ASPCA Animal Poison Control website. Accessed March 9, 2018.
Top 10 plants poisonous to pets. Pet Poison Helpline website. Accessed March 9, 2018.

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