Make the introduction in a highly controlled environment. It is best to have two people, one holding the new dog while the other praises each animal. Keep the dog on leash. Firmly correct your dog at the first hint of undesired behavior, and don’t unleash her around your cat until they are interacting calmly. A chase may ensue if the cat runs.
During the introduction period, make sure you are supervising when they are in the same room in case trouble breaks out. Warning signs in cats include a direct stare, elevated hindquarters, and fur standing on end. If the pets seem to be accepting each other, praise each animal and reward them with treats and petting.
Be careful not to praise undesired behaviors. For example, petting and soothing an agitated or growling animal will reinforce the wrong response. Reward only calm, desirable or at least neutral behavior.
A dog with a high prey-drive can be taught to coexist with cats; however, this requires concentrated practice. It is best to seek the help of a professional for dog training.
Litter box accidents can occur during this introduction period because cats may be disturbed by the newcomer. Your cat may hide or seek higher ground for days or weeks until she is ready to accept the dog. Make sure she has places to retreat that the dog cannot access. You can attach a bell to the new dog’s collar to keep track of his whereabouts. Also be sure to block the dog’s access to the cat’s food and litter box.
Training a dog to leave small animals alone requires patience, and can take weeks. For the animals’ safety, don’t leave them alone together until you are confident that your new dog is on friendly terms with your cat.