This Nice Blog for your Question that I read on Internet. I want to share this to you which may be helpful to you...
Here is the blog...
Old Dog Meets New Dog – A Lesson in Breath Holding
Posted January 30th, 2009 by dogdude
You love your dog. He is your friend, your burglar alarm, your playmate, and your comfort when you’re blue. He is a member of your family. But families tend to grow, and often they grow because a new dog is going to be moving in. Whatever reasons that you may have for bringing the new dog in, you want the old dog to be okay with it. Actually, you want the old dog to be ecstatic about it. You want him to jump and bark and run around in circles and look happier than he does when you say the word “walk”.
Let’s be realistic here. Be satisfied at first with grudging acceptance.
We like to talk to our dogs. However, sitting the old dog down for a heart to heart about how much you love him and how nobody can take his place in your heart is heartwarming (especially if you cue some emotional music), but probably not too helpful. What your dog will hear is “blah blah…blah blah blah.” Unless the word “walk” is in there somewhere, he is neither going to know nor care about what you’re saying.
You need to realize that there really is no way to prepare your old dog for the new dog, so you have to concentrate on helping the introduction go as smoothly as possible. One of the best ways to do this is to introduce them on neutral ground. You may think that it’s your house, but to your dog it is his territory. Introducing the dogs there may cause some friction. It would be like some stranger coming into your house and exclaiming, “Yes, this looks nice! I’ll start moving my stuff in!”
Fortunately dogs tend to make friends faster than people do. If you introduce the two dogs at a park, another person’s house, or anywhere away from where you and your dog live, they might hit it off fairly quickly. Older dogs tend to accept puppies easier than they do other older dogs, although older male dogs accept older female dogs fairly easily too.
No matter what, if you introduce the dogs in a casual, calm atmosphere and simply let them work things out (intervening if there’s any real fighting, of course), then things could work out well. When it’s time to bring the new dog into the home, bring them in together—after they have established some type of initial relationship.
At this point you need to curb the urge to interfere as your dogs get to know each other. Let them establish the pecking order, as long as you don’t let them forget that you are top dog around there. The older dog, of course, may never have believed that, but it’s good for your ego to think that he has all along.
Feed them far apart from each other at first. Food fights may conjure up amusing memories for you, but it doesn’t mean the same in the dog world. If your older dog has any toys, don’t give them to the new dog to play with. Give the new dog his own toys. Eventually, if all goes well, they’ll start sharing.
The one thing that you need to remember is that dogs tend to be much more reasonable than people. This works in your favor. Let them work out the specifics while you oversee, and things really should work out fine. Most likely the worst that will happen is you’ll be bossed around by two dogs instead of one; but hey, you asked for it!
Courtesy: https://www.breederretriever.c om/blog/