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