Yes, Geranium is toxic to dogs!
Dogs accidentally consuming the Geranium 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).
Geranium consumption is also toxic to Cats and Horses.
Toxic Principles Of Geranium: Geraniol, linalool.
More Info About The Geranium Plant
Scientific Name: Pelargonium species
Family: Geraniaceae.
Also known as: Many cultivars.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.