Yes, Pie Plant is toxic to dogs!
Dogs accidentally consuming the Pie Plant 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).
Pie Plant consumption is also toxic to Cats and Horses.
Toxic Principles Of Pie Plant: Soluble calcium oxalates.
More Info About The Pie Plant Plant
Scientific Name: Rheum rhabarbarium
Family: Polygonaceae.
Also known as: Rhubarb.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.