Yes, Poison Parsnip is toxic to dogs!
Dogs accidentally consuming the Poison Parsnip plants can show the following clinical symptoms: Vomiting, Prolonged Depression, Incoordination, Hypersalivaton, Sleepiness Or Excitation, Dilated Pupils, Low Body Temperature, Low Blood Pressure, Coma, Seizure And Death (In Rare Cases).
Poison Parsnip consumption is also toxic to Cats and Horses.
Toxic Principles Of Poison Parsnip: Cicutoxin.
More Info About The Poison Parsnip Plant
Scientific Name: Cicuta maculata
Family: Apiaceae.
Also known as: water hemlock, cowbane.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.