Yes, Sowbread is toxic to dogs!
Dogs accidentally consuming the Sowbread 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).
Sowbread consumption is also toxic to Cats.
Toxic Principles Of Sowbread: Terpenoid saponins.
More Info About The Sowbread Plant
Scientific Name: Cyclamen spp
Family: Primulaceae.
Also known as: Cyclamen.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.