Introducing a new dog to your pack at home has to be prepared for - to avoid tension & aggression between the canines.
Always remember that some dogs may get along with a new family and existing pets in the household better than others. You may want to put some thought on the breed, age, and temperament of the new dog to add to your pack.
It is best to assess the new dog if he or she would fit into your pack at home or get along well with your resident dog (if you only have one at the moment).
You can get some advice from the nearest person in contact... from where you are getting your new dog - it could be a staff from the rescue centre or your trusted professional breeder.
You can use a common thing that your pack or resident dogs use in a regular basis - it could be a doggie blanket, toys, or something similar.
Get in touch with the rescue centre or professional breeder you are getting your new dog from and ask them to help you get the scent.
Bring the doggie blanket back to your house and let your resident dogs smell it or play with it - this will help them slowly associate the new dog’s scent to something pleasant and familiar.
This is the best way to conduct the first introduction between the dogs. Being in a neutral territory such as a dog park solves common yet underlying territorial and dominance problems.
In this way, your resident dog will not feel challenged in his territory since you are not bringing a stranger dog into his den. On the other hand, the new dog will then feel safer and more comfortable around your existing dog.
Allow the two dogs to meet each other in a relaxed manner - this may start with some sniffing, nose-to-nose contact, and eventually play. Make sure that the dogs are well supervised during this phase.
Assuming that the meet-up at the dog park or in any neutral territory went really well, the next best thing to do is to “invite” the new dog for a playover with your pack or resident dog.
This may take an entire day or a few hours in a day. Allow the new dog and your resident dogs to play in your yard and even inside the house - remember to hide anything that the dogs may compete for such as food, toys, and treats.
A playover will give both dogs such a great time to adjust and know each other really well and get along even in the established territory of your pack or resident dog.
This will also help you decide if you will really get a new dog (in case you’re having second thoughts) - if things go well, go for it!
If not, you may need to talk to the rescue centre, or the professional breeder, or even a dog behaviourist to help you with your options.
Finally, if things went well with the playover stage, it’s time to welcome the new dog to the pack! The adjustment between your resident dogs and the new dog will continue. So, it is best to supervise them as much as possible.
Alot a specific place or bed for the new dog to stay at, get a new bowl for food and water for the new addition to your pack - if possible, feed the dogs in separate rooms.
Make sure to spend one-on-one time with each dog without having to compromise your attention towards the other - you can do this by walking just one dog at a time.
When spending time with your dogs, get some treats ready and reward them for good behaviours - especially the resident dogs if they behave well when they’re around the new dog.
If things don’t go too well within this stage, do not punish the aggressor. Just try to separate the dogs for some time.
Then, continue to reinforce pleasant association between the dogs such as a playtime together, or by giving them equal pats on the head, treats, and toys when they’re together.
Please remember that getting a pet is a lifetime commitment. Thus, getting a second dog or an addition to your pack requires more effort, patience, and love.