Toxic Plants Checklist: The 12 Most Poisonous Plants to Dogs

An important step in dog ownership involves learning if you own toxic plants. Many pet owners are surprised to learn that the medicinal aloe vera plant can harm their dog. Thirteen commonly owned toxic indoor and outdoor house plants are listed below.

Aloe Vera Are Toxic Plants

Aloe vera are succulents that benefit humans in many ways including acting as a soothing salve for burns. While the gel inside the leaves is okay for dogs, the outer leaves contain saponins that cause diarrhea, nausea, tremors and vomiting.

Apple and Cherry Trees

If you own land, you may well own an apple or cherry tree. All parts of an apple tree or cherry tree are toxic to dogs. The stems, leaves and seeds of the apple contain cyanide. Symptoms of a poisoning by these toxic plants include:

  • Breathing difficulties
  • Dilated pupils
  • Panting
  • Shock

Asparagus Ferns

Asparagus ferns are commonly found inside homes in hanging baskets. The toxic plants contain sapogenins that cause allergic dermatitis. If the plant forms berries, the berries cause abdominal pain, diarrhea, nausea and vomiting.

Azaleas and Rhododendrons

Considered the prettiest flowering shrubs in the spring months, azaleas and rhododendrons are found in gardens throughout the country. They contain grayantoxin in all areas of the plant. Grayantoxins affect muscle and nerve function causing a number of symptoms:

  • Colic
  • Depression
  • Diarrhea
  • Dizziness
  • Excessive drooling
  • Loss of appetite
  • Paralysis of the legs
  • Slowed heart function
  • Weakness

Christmas Cactus

Many homes have the colorful house plants sitting dormant until the holiday season. Christmas cactus is toxic to dogs. Ingesting the leaves, flowers or branches causes bloody diarrhea, depression and vomiting.

Clematis Vines

Experienced gardeners often have clematis vines trailing up trellises in their gardens. The large, showy flowers are prized blooms, but they contain protoanemonin. This irritant causes diarrhea, excessive drool and vomiting in dogs.

Common Privet Hedge

It seems every garden has privet hedge. The dense hedges create natural fencing. The needles and branches of privet hedge contain terpenoid glycosides, a toxin that causes:

  • Intestinal upset
  • Loss of balance and coordination
  • Racing heart


Homeowners enjoy filling their home with the scent of eucalyptus branches, however it is also toxic to dogs. The eucalyptus oil causes depression, diarrhea, excessive drooling, lethargy and vomiting.


If you have garlic in your vegetable garden, keep dogs out of it. Garlic contains N-propyl disulfide, a toxin that causes:

  • Blood in urine
  • Deterioration of red blood cells
  • Lethargy
  • Panting
  • Rapid heartbeat


Because it thrives in a shade garden, hosta is found in many yards. However, the toxic plants contain saponins that cause depression, diarrhea and vomiting in dogs.

Red Maple Trees

Throughout the eastern portion of North America, red maple trees create vivid color in many yards and forests. If a dog eats the leaves, they impair red blood cell function. Symptoms of red maple poisoning include:

  • Abdominal pain
  • Change in urine color
  • Darkened eye and mouth membranes
  • Dog founder (inflamed paw)
  • Lack of appetite
  • Lethargy


Rhubarb thrives in many gardens. While it's a great treat when cooked into a dessert, the leaves and uncooked roots contain soluable calcium oxalates. This toxic acid causes excessive drool, kidney failure and tremors.