Toxic — keep away from pets
Yes — dieffenbachia (dumb cane) is toxic to dogs and cats. Its calcium oxalate crystals cause intense mouth burning and swelling, and its nickname comes from the temporary speech-blocking effect in people.
Dieffenbachia, aptly nicknamed “dumb cane”, contains insoluble calcium oxalate crystals plus proteolytic enzymes that make its sting particularly fierce. A pet that chews it gets immediate, intense burning of the mouth, lips and tongue, heavy drooling and swelling. In rare cases the swelling can be severe enough to interfere with swallowing or breathing. It is a very common, easy-care houseplant, so accidental exposures are not unusual.
Both dogs and cats react the same way. Curious chewers, kittens and puppies are most at risk.
Rinse the mouth and offer water or milk to flush the crystals, and monitor for swelling. Most pets recover, but seek veterinary care urgently if there is significant swelling, trouble breathing or swallowing, or persistent vomiting — call a poison helpline if unsure. Keep dieffenbachia well out of reach of pets.
Related: Is philodendron toxic? · Is pothos toxic? · Is peace lily toxic?
General information, not veterinary advice. If your pet has eaten a toxic plant or shows symptoms, contact your vet or a pet poison helpline immediately. Full disclaimer.