Dogs
Potentially toxicConsulted references classify the plant as toxic or irritating for that pet type.
Verified against ASPCA/provenance audit 2026-05-06 on May 6, 2026.
Sources
dog safety reference
Is Cow Parsnip safe for dogs?
Heracleum maximum
Cow parsnip is a large, herbaceous perennial member of the carrot family known for its tall stature and umbrella-like flower clusters. It contains furanocoumarins that can cause significant skin and mucosal irritation upon contact.
American cow parsnipCow parsnipHeracleum lanatumHeracleum maximum
- Light
- Partial shade to full sun
- Habit
- Herbaceous perennial
- Care
- Low
Safety status
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.
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.
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.
Sources: ASPCA.
If a pet has chewed or swallowed plant material and is showing symptoms, contact a veterinarian or poison resource immediately. This product is for structured reference, not diagnosis.
Dogs — concern notes
Common signs
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.
Safer alternatives
No hand-picked alternatives for this plant yet. You can still pick your own using the Compare button on any other plant.
Source evidence
ASPCA Toxic Plant List
toxicology · 99% reliability
Cow parsnip is listed as toxic to both cats and dogs due to its potential for causing dermatitis and irritation.
Questions about Cow Parsnip
Is cow parsnip toxic to dogs?
Yes, cow parsnip (Heracleum maximum) is potentially toxic to dogs. Its sap contains furanocoumarins that cause skin inflammation, blistering, and oral irritation, and can lead to gastrointestinal upset if ingested.
What does cow parsnip poisoning look like on a dog's skin?
Skin reactions appear as redness, blistering, or peeling on areas the sap contacted — commonly the muzzle, lips, belly, and paws. The reaction is driven by phytophotodermatitis: the sap makes skin hypersensitive to UV light, so symptoms develop over 24–48 hours after sun exposure and can take 1–2 weeks to fully heal. Reactions are significantly worse if the dog goes outside in sunlight after contact.
What should I do if my dog touched or chewed cow parsnip?
Bring your dog inside immediately and keep them away from sunlight. Wearing gloves, wash all contact areas thoroughly with soap and cool water, and rinse the mouth if the dog chewed any leaves. Do not induce vomiting. Call your vet or the ASPCA Animal Poison Control Center at (888) 426-4435.
When is cow parsnip exposure in dogs an emergency?
Call your vet promptly — don't wait it out — 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; early treatment reduces the risk of serious skin damage.
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