Yes, Dieffenbachia is toxic to dogs!
Dogs accidentally consuming the Dieffenbachia 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).
Dieffenbachia consumption is also toxic to Cats.
Toxic Principles Of Dieffenbachia: Insoluble calcium oxalates, proteolytic enzyme.
More Info About The Dieffenbachia Plant
Scientific Name: Dieffenbachia
Family: Araceae.
Also known as: Charming Dieffenbachia, Giant Dumb Cane, Tropic Snow, Dumbcane, Exotica, Spotted Dumb Cane, Exotica Perfection.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.