Safety verdict
Consulted references classify the plant as toxic or irritating for that pet type.
Pet ingestion lookup
My dog ate Cow Parsnip - what should I do?
Heracleum maximum
Potentially toxic
Contact your veterinarian or an animal poison-control resource now, especially if any amount was chewed or swallowed.
Verified against ASPCA/provenance audit 2026-05-06 on May 6, 2026.
Signs to watch for
Skin inflammation, blistering, oral irritation, and potential gastrointestinal upset.
Escalation note
Contact with the sap can lead to phytophotodermatitis, where skin becomes hypersensitive to UV light. Seek veterinary care if your pet shows signs of distress or skin lesions.
First aid at home
Bring the dog inside, away from sunlight. With gloves on, wash the contact areas thoroughly with soap and cool water and rinse the mouth if the dog has chewed leaves. Do not induce vomiting. Call your vet or ASPCA Animal Poison Control at (888) 426-4435.
What to watch for
Drooling and oral irritation if the dog chewed or ate the plant; red, blistered, or peeling skin on the muzzle, lips, belly, paws, or anywhere else the sap touched; itchiness or pawing at the burn site. Reactions intensify markedly with sun exposure.
Time window
Skin reactions develop over 24–48 hours after the contact area is exposed to sunlight, and lesions can take 1–2 weeks to heal. Oral irritation usually subsides within 24 hours once the dog stops contacting the plant.
When to call the vet
Call promptly if you see blistering or open skin lesions, swelling around the mouth, persistent drooling, or refusal to eat. Severe phytophotodermatitis can ulcerate and become infected, so don't wait it out.
What this means for your dog
Dogs — toxic. ASPCA classifies cow parsnip as toxic to dogs; the furanocoumarins in the leaves and sap cause phytophotodermatitis, a sun-activated chemical burn on skin that contacted the plant. Dogs are most often exposed by brushing through stands of cow parsnip on walks or by chewing the stems.
Sources: ASPCA.
Source references
Poison-control resources
This page summarizes source-bound plant-safety information and is not veterinary advice.