Yes, Bittersweet can be toxic to dogs.
Scientific Name: Colchicum autumnale
Bittersweet is a common house/yard plant.
Additional Common Names: Bittersweet, Meadow Saffron or Naked Lady.
Toxic Principle: Colchicine and other alkaloids. The symptoms of colchicine poisoning resemble those of arsenic, and no antidote is known.
Poisoning Symptoms include Oral irritation, bloody vomiting, diarrhea, shock, multi-organ damage, bone marrow suppression.