Yes, Bitter Root is toxic to dogs!
Dogs accidentally consuming the Bitter Root 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).
Bitter Root consumption is also toxic to Cats and Horses.
Toxic Principles Of Bitter Root: Cardenolides.
More Info About The Bitter Root Plant
Scientific Name: Apocynum androsaemifolium
Family: Apocynaceae.
Also known as: Dogbane Hemp, Indian Hemp.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.