Yes, Sweetheart Ivy is toxic to dogs!
Dogs accidentally consuming the Sweetheart Ivy 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).
Sweetheart Ivy consumption is also toxic to Cats and Horses.
Toxic Principles Of Sweetheart Ivy: Triterpenoid saponins (hederagenin).
More Info About The Sweetheart Ivy Plant
Scientific Name: Hedera helix
Family: Araliaceae.
Also known as: English Ivy, Glacier Ivy, Needlepoint Ivy, Branching Ivy, California Ivy.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.