Yes, Onion is toxic to dogs!
Dogs accidentally consuming the Onion 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).
Onion consumption is also toxic to Cats and Horses.
Toxic Principles Of Onion: N-propyl disulfide.
More Info About The Onion Plant
Scientific Name: Allium cepa
Family: Liliaceae.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.
