Yes, Peace Begonia is toxic to dogs!
Dogs accidentally consuming the Peace Begonia 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).
Peace Begonia consumption is also toxic to Cats and Horses.
Toxic Principles Of Peace Begonia: Soluble calcium oxalates.
More Info About The Peace Begonia Plant
Scientific Name: Begonia rex ‘peace’
Family: Begoniaceae.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.