Is Poison Hemlock Toxic to Cats?
Also known as: Deadly Hemlock, Poison Parsley, Conium maculatum · Conium maculatum
What makes it toxic
Piperidine alkaloids, chiefly coniine and gamma-coniceine, in all parts of the plant. They block nerve signals to muscles, progressing to respiratory paralysis; roots are the most concentrated.
Warning signs to watch for
Drooling, vomiting, weakness, trembling, dilated pupils, a slowing heartbeat, cold limbs, then paralysis and difficulty breathing within hours.
What to do if your cat eats it
This is a life-threatening emergency. Go to a vet or animal ER immediately, bringing the plant for identification. Do not wait for symptoms — breathing support must start before paralysis sets in.
Common questions
How do I recognize poison hemlock?
Look for ferny lacy leaves, small white umbrella-shaped flowers and distinctive purple blotches on the smooth hollow stems. It grows along ditches and roadsides and resembles wild carrot.
Is dried hemlock in hay still toxic?
Yes — the alkaloids persist in dried material, so dried plants in hay, mulch or grass cuttings remain dangerous.
Is it related to water hemlock?
Different genus, equally deadly. Cicuta (water hemlock) causes seizures; Conium causes paralysis. Treat both as lethal.
More plants checked for cats
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.