What Is Poison Hemlock? Could It Kill Your Pets?

The war against weeds in your yard can be a constant, but necessary, battle if you want to maintain a lawn and garden that look their best. 

There are well-known harmful weeds that can invade your yard, and are on most people’s radar, like poison oak and poison ivy, but poison hemlock is one infamous weed whose presence seems to be exploding in parks and gardens across the country this season.

Poison hemlock is biennial, which means it’s a flowering plant that takes two years to complete its biological life cycle. It reaches full bloom in summer and has beautiful umbrella-shaped clusters of tiny white flowers at the end of each stem. It very much resembles Queen Anne's lace.

Don’t be fooled, though. This deceptively beautiful plant is highly toxic to humans, livestock—and your dog or cat.

Toxicity

All parts of poison hemlock are dangerous, from stems to blooms. The weed contains a neurotoxin that can cause major problems if your pet consumes it in large amounts. 

Signs your pet has been poisoned 

You should keep a vigilant eye on your dog if it’s the type that likes to chew on flowers, leaves, and other wild foliage during walks and while in your yard. If you think your pet has ingested this poisonous plant you should look for symptoms like gastrointestinal upset and vomiting. Initial overexcitement in your pet, followed by weakness and a depressed disposition, are also signs, say veterinarian toxicologists at the Pet Poison Hotline. Symptoms like these may warrant a call to the hotline, or a trip to the vet.

In the most severe cases your dog may experience coma-like signs and significant respiratory distress, like shallow or difficult breathing, and even paralysis of the respiratory muscles.

These types of symptoms would indicate more than a small, one-time exposure to poison hemlock, say veterinarian toxicologists.

In such cases, depending on the symptoms and severity of your dog’s condition, veterinarians can safely induce vomiting or defecation, and provide breathing assistance for your pet.