Yes, Black Nightshade is toxic to dogs!
Dogs accidentally consuming the Black Nightshade 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).
Black Nightshade consumption is also toxic to Cats and Horses.
Toxic Principles Of Black Nightshade: Solanine, saponins, atropine like substances.
More Info About The Black Nightshade Plant
Scientific Name: Solanum nigrum
Family: Solanaceae.
Also known as: Nightshade, Deadly Nightshade.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.