The best way to prepare your dog for a new arrival is to socialize early with other dogs. Knowing your dog’s personality – aggressive, anxious, fearful? – will help determine how to handle the arrival of a new dog.
If you have a multi-dog household, introduce the new dog one at a time so as not to overwhelm the newcomer. I introduced my new dog on leash, but it is also advised to allow them to meet in a fenced-in, open area off leash. In this way neither dog feels threatened without an escape route.
The first meeting should be a short one, leaving the dogs with positive feelings. You can increase the amount of time together if you see no problems. If you must leave the dogs alone at first, it’s best to separate them. Either put them in their individual crates or separate rooms.
Allow the new dog to explore your home without other dogs, so that the new one becomes familiar with its surroundings.
When feeding your dogs, allow each one to have its own special feeding area to avoid food fights.
Don’t let them stare at each other as this is a sign of aggression.
Take the dogs for walk together. This can be a good bonding time.
Give your other dog(s) lots of attention so they don’t feel left out.
There are times when dogs will never get along despite all your attempts. Then you must decide whether you want to live with being constantly on guard against a fight breaking out or finding another home for the new dog.