Yes, Heartleaf Philodendron is toxic to dogs!
Dogs accidentally consuming the Heartleaf Philodendron 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).
Heartleaf Philodendron consumption is also toxic to Cats and Horses.
Toxic Principles Of Heartleaf Philodendron: Insoluble calcium oxalates.
More Info About The Heartleaf Philodendron Plant
Scientific Name: Philodendron bipennifolium
Family: Araceae.
Also known as: Horsehead Philodendron, Cordatum, Fiddle-Leaf, Panda Plant, Split Leaf Philodendron, Fruit Salad Plant, Red Emerald, Red Princess, Saddle Leaf.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.