Yes the Cyclamen Plant is a very poisonous plant to both cats and dogs and can cause death if the dog or cat eats the cyclamen plant.
If your cat or dog ingests or eats any part of the cyclamen plant it can lead to Salivation, vomiting, diarrhea, heart rhythm abnormalities, seizures and like I mentioned above death.'
So you should keep your cat and dogs away from any cyclamen plant and if the dog or cat eats any part of the cyclamen plant the cat or dog needs to see a vet.
Otherwise the dog or cat will die within 24 hours or less so make sure the dog or cat gets treatment after eating or ingesting any part of the cyclamen plants.