Holly Berries Dogs. Holly is toxic to dogs, reports the u.s. Certain types of yuletide plants (e.g., mistletoe, rosemary, holly berries, etc.) can be toxic to pets.
Shrubs that are poisonous to dogs eating even a few leaves can cause serious issues, including vomiting, diarrhea, drooling, paralysis, shock, coma, and death. What happens if a dog eats a holly berry? Holly berries have substances like cyanogens, saponins, and methylxanthines that can cause vomiting and diarrhea.