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Is Water Hemlock Toxic to Dogs?

☠️ ToxicSeverity: Severe
✅ Cross-checked against veterinary poison-control guidance · Oct 2026 audit
⚠️ Educational info only. If your pet just chewed something and looks unwell, skip the reading and call your vet or Pet Poison Helpline (US): (855) 764-7661.
Yes — water hemlock is severely and often fatally toxic to dogs. It is considered the most violently poisonous plant in North America, killing by seizures within hours.

Also known as: Cowbane, Beaver Poison, Musquash Root, Cicuta maculata · Cicuta maculata

What makes it toxic

Cicutoxin, an unsaturated alcohol neurotoxin densest in the roots and their sap. It disrupts GABA-like inhibition in the brain, producing seizures that exhaust the heart and breathing muscles.

Warning signs to watch for

Within minutes to an hour: frothing, vomiting, dilated pupils, anxiety, then sudden violent seizures with jaw clamping, rigid muscles and rapid heartbeat. Repeated convulsions lead to respiratory failure and death.

What to do if your dog eats it

Drive straight to the nearest emergency vet with a piece of the plant. Tell staff water hemlock specifically — teams prepare seizure control and ventilation in advance. There is no antidote; speed is the treatment.

Common questions

Can a dog die from chewing one water hemlock root?

Yes — this is documented repeatedly in livestock and pets. The root is the most toxic part, and a mouthful has been lethal. Treat any root contact as immediately fatal-risk.

How do I tell water hemlock from safe look-alikes?

Look for the combination: wet habitat, hollow stems with purple streaks, ferny divided leaves, white umbel flowers and roots that smell like parsnip. When unsure near pets, treat it as water hemlock and keep them away.

More plants checked for dogs

Pothos☠️ ToxicYes, pothos is toxic to dogs. Chewing any part of the vine releases calcium oxalate crystals thaAloe Vera⚠️ Mildly ToxicAloe vera is mildly to moderately toxic to dogs. The skin and latex layer of the leaf contain coSpider Plant✅ Non-ToxicNo, spider plants are non-toxic to dogs. A dog that nibbles the arching leaves is not at risk ofEaster Lily⚠️ Mildly ToxicEaster lilies are only mildly toxic to dogs — they usually cause stomach upset, not the fatal kiSago Palm☠️ ToxicYes — sago palm is severely toxic to dogs, with a documented fatality rate around 50% when untreBoston Fern✅ Non-ToxicNo, Boston ferns are non-toxic to dogs. Chewing a frond will not poison your dog.

This page is general educational information, not a substitute for professional veterinary advice. Every pet is different — if your animal ate something concerning, contact your veterinarian or a pet poison hotline right away. Checking what your pet can eat? Visit our sister site SafeOrToxic.