is christmas cactus poisonous to dogs

Yes, it can be toxic to dogs. The Christmas cactus, or schlumbergera, contains a compound called oxalate, which can cause irritation to the mouth and stomach lining, leading to drooling, vomiting, diarrhea, and difficulty breathing. It's important to keep the plant out of reach of pets and to seek veterinary care if your dog has ingested any part of the plant.