Yes, Mayapple is toxic to dogs!
Dogs accidentally consuming the Mayapple 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).
Mayapple consumption is also toxic to Cats and Horses.
Toxic Principles Of Mayapple: Podophyllin.
More Info About The Mayapple Plant
Scientific Name: Podophyllum peltatum
Family: Berberidaceae.
Also known as: Indian Apple Root, Umbrella Leaf, Wild Lemon, Hog Apple, Duck’s Foot, Raccoonberry, American Mandrake.
The answer is based on information found on The American Society for the Prevention of Cruelty to Animals (ASPCA) website.