Is Poison Hemlock safe for cats and dogs?
| Species | Verdict |
|---|---|
| Cats | Toxic |
| Dogs | Toxic |
Severity: Severe
Read the full first-aid guide: what to do if your pet ate something toxic
Poison hemlock is one of the most dangerous plants a pet owner in California is likely to walk past without noticing. UC's Statewide Integrated Pest Management Program (UC IPM) documents it growing throughout the state - everywhere except the deserts and the Modoc Plateau, up to about 3,300 feet elevation - along roadsides, ditch banks, and pastures, and occasionally spreading into vineyards and orchards planted in low-lying riparian ground. It looks enough like wild carrot, parsley, or fennel that both people and animals have mistaken it for something edible; that resemblance, not deliberate landscaping, is the real exposure pathway here.
ASPCA lists poison hemlock (Conium maculatum) as toxic to both dogs and cats, with various alkaloids as the toxic principle and clinical signs of agitation, tremors, drooling, diarrhea, paralysis, and death. Pet Poison Helpline independently describes it as a highly toxic plant that rapidly causes neurologic signs in dogs and cats as well as grazing animals like cattle, horses, and small ruminants, and advises that immediate veterinary examination is warranted for any ingestion, regardless of how the pet looks in the moment - onset can be fast. If a dog or cat has been anywhere near a stand of feathery, carrot-like weed with purple-spotted stems and starts showing tremors, drooling, or weakness, treat it as an emergency: call ASPCA Animal Poison Control (888-426-4435) or Pet Poison Helpline (855-764-7661) on the way to the vet.
Facts and examples
- Poison hemlock is found throughout California except the deserts and the Modoc Plateau, up to about 3,300 feet elevation, and infests roadsides, ditch banks, and pastures, sometimes invading vineyards and orchards planted in low-lying riparian areas. (source, verified 2026-07-29)
- ASPCA lists poison hemlock (Conium maculatum) as toxic to both dogs and cats, toxic principle 'various alkaloids', with clinical signs of agitation, tremors, drooling, diarrhea, paralysis, and death. (source, verified 2026-07-29)
- Pet Poison Helpline describes poison hemlock as a highly toxic plant that rapidly causes neurologic signs in dogs and cats as well as grazing animals, and advises immediate veterinary examination for any ingestion. (source, verified 2026-07-29)
Verdict re-verified against aspca.org, 2026-07-29 — confirmed unchanged. Source
This page is for general information only and is not veterinary advice, diagnosis, or treatment. If your pet is showing symptoms, or you think they ate or touched something dangerous, contact your veterinarian or a pet poison-control hotline immediately.
Last verified 2026-07-29