Honeysuckle contains cyanogenic glycosides and saponic glycosides, making all parts of the plant toxic to dogs, according to Garden Guides. Honeysuckle berries have carotenoids, which dogs are not able to process in large quantities.
Saponic glycosides make a dog's blood froth, leading to blood cell rupture. Cyanide is made when cyanogenic glycosides meet with stomach acids. Some of the symptoms of honeysuckle poisoning include vomiting, diarrhea, confusion, unconsciousness, coma, depression, loss of appetite and seizure. Honeysuckle poisoning can be fatal. If there is a suspicion of honeysuckle poisoning, take the dog to the veterinarian for treatment as quickly as possible.