It's widely believed that cats and dogs cannot live together peacefully. While that may be true in some situations, most of the time, they can and do learn to tolerate each other and even develop friendships. Whether or not there's harmony in a "mixed" home depends on the personalities of the individual cat and dog. How well things start also depends on the pet parent's preparation for the first meeting of the two.
According to PetMD, cited below, the introduction of the cat and dog require careful steps. Still, safety comes first: "Fully quarantine any new pet for a minimum of three to four days, and have a health assessment done by your veterinarian before the introduction process begins."
The quarantine also gives the cat and dog time to "sense" each other. That means they'll sniff each other under the door that keeps them separated and maybe even "talk" to each other. PetMD says it's best to put the new pet behind the door first, then switch places after a few days and let the cat get his bearings in the other rooms.
According to PetMD, "The goal is for them to have plenty of opportunities to acclimate to each other's smells and noises before ever seeing each other."
Once the sniffs and meows have been offered, it's time to let the two animals see each other. At first, use a barrier, such as a glass door or pet gate. Try to make these "peek-a-boo" sessions positive. Offer treats to each pet while they are separate from, but still mindful, of each other. Be watchful for "resource guarding" since food is a primary resource for the animal and could cause the two to fight. If this step isn't going well, keep the two separated and contact your vet or a trainer for advice. Remember: first contact will control the future relationship between the two.
According to the Animal Humane Society, cited below, the next step is the meet and greet. The experts say that for best results: "Once your pets can eat their food calmly right next to the door, conduct a physical meet and greet in a common area of the house. Don't use either animal's sanctuary area. Keep the first few sessions short and calm. Keep the dog on a leash and let the cat come and go as he wishes."
Monitor the meetup, and if things get dicey, separate the animals again behind the pet gate or door. Animal Humane Society suggests repeating these meetings daily until the two seem more comfortable in one another's presence. "Save your pets' favorite treats for when they are together. If the cat attempts to leave the room, allow him to do so, and do not let the dog chase him. Try to end each session before either pet shows stress or aggression."
Bringing a cat into a home already furnished with a dog can be challenging. The pet parent must pay close attention to both the dog and cat and be ready to break up any fights. Animal Humane Society says once the two seem to be getting along, let them loose in the same room, but "Keep the dog's leash attached and dragging on the floor so that you can step on it and prevent him from chasing the cat if he gets excited. If tension erupts, go back to the earlier introduction steps and repeat the process. Make sure the cat has access to a dog-proof sanctuary room at all times."
No matter how well the dog and cat seem to get along, do not leave them in the same room when no one is home. That will be necessary for some cats and dogs for a short time. Or, it may take months to safely leave them together when no one's around. But in most cases, it will happen and one day, you may catch your dog and cat laying together, best buddies.
Quote to remember: "No matter what you've done wrong, always try to make it look like the dog did it." - The Cat
"How to introduce a cat to a dog"
Animal Humane Society
"How to introduce a dog and cat"