I'm sure you don't need to be told: you'll need to be careful when introducing a dog and a cat to one another. A dog can seriously injure and even kill a cat very easily, even if they're only playing—all it takes is one quick shake to break the cat's neck. Some dogs have such a high prey drive they should never be left alone with a cat. Dogs usually want to chase and play with cats, and cats usually become afraid and defensive. Here are some techniques to use to begin introducing your new cat to your resident dog:

Obedience

If your dog doesn't already know the commands "sit," "down," "come," and "stay," begin working on them right away. Small pieces of food will increase your dog's motivation to perform, which will be necessary in the presence of a strong distraction such as a new cat. Even if your dog already knows these commands, work to reinforce these commands in return for a tidbit.

Controlled First Time Meeting

After your new cat and resident dog have become comfortable eating on opposite sides of the door and have been exposed to each other's scents, you can attempt a face-to-face introduction in a controlled fashion. Put your dog's leash on and have him either sit or lie down and stay for treats. Ask another family member or friend to enter the room and quietly sit down next to your new cat, but don't ask them to physically restrain her. Have this person offer your cat some special pieces of food. At first, the cat and the dog should be on opposite sides of the room. Lots of short visits are better than a few long visits. Don't drag out the visit so long that the dog becomes uncontrollable. Repeat this step several times until both the cat and dog are tolerating each other's presence without fear, or aggression.

Let Your Cat Go

Allow your cat some freedom to explore your dog at her own pace, with the dog still on-leash and in a "down-stay." Keep giving your dog treats and praise for his calm behavior. If your dog gets up from his "stay" position, repositioned with a treat lure, and praised and rewarded for obeying the "stay" command. If your cat runs away or becomes aggressive, you're progressing too fast. Go back to the previous introduction steps.

Positive Reinforcement

Although your dog must be taught that chasing or being rough with your cat is unacceptable behavior, he must also be taught just what is appropriate, and be rewarded for those behaviors, such as sitting, coming when called, or lying down in return for a treat. If your dog is always punished when your cat is around, and never has "good things" happen in the cat's presence, your dog may redirect aggression toward the cat.

Directly Supervise All Interactions between Your Dog and Cat

You may want to keep your dog at your side and on-leash whenever your cat is free in the house during the introduction process. Be sure that your cat has an escape route and a place to hide. And until you're certain your cat will be safe, be sure to keep the two separated when you aren't home.

Precautions

It's no surprise that dogs like to eat cat food, so you'll need to keep the cat's food out of your dog's reach. It's not uncommon for dogs to eat cat feces as well, and though there are no real health hazards involved, it's probably distasteful to you and it maybe just as upsetting to your cat. Punishment after the fact will not change your dog's behavior. The best solution is to place the litter box where your dog can't access it, for example: in a closet with the door propped open just wide enough for your cat; or inside a tall, topless cardboard box with easy access for your cat.

Kittens and Puppies

Because they're so much smaller, kittens are in more danger of being injured or killed by a young energetic dog, or by a predatory dog. A kitten will need to be kept separate from an especially energetic dog until she is fully grown, except for periods of supervised interaction to enable the animals to get to know each other.

Even after the cat is fully grown, she may not be able to be safely left alone with the dog. Usually, a well-socialized cat will be able to keep a puppy in his place, but some cats don't have enough confidence to do this. If you have an especially shy cat, you might need to keep her separated from your puppy until he matures enough to have more self-control.

When to Get Help

If introductions don't go smoothly, seek professional advice immediately from a veterinarian or animal behaviorist. Animals can be severely injured in fights, and the longer the problem continues, the harder it can be to resolve. Punishment won't work, though, and could make things worse. Luckily, most conflicts between pets in the same family can often be resolved with professional guidance.