Question regarding the possibility of adding a new puppy to the family.

Hello everyone, this is my first post here, basically I'll jump right in with my question, I have a 12 year old staffordshire bull terrier named Tags, he is a lovely dog who just wants to play and eat all day. I've had him since he was a pup and he is basically great at everything! But he doesn't have a lot of experience being around other dogs, he's never mated, and has rarely been around other dogs for a long period of time. When he is passing other dogs in the street he doesn't act alarmed at all, just tries to walk over to sniff them, and doesn't bark or growl at other dogs. He does moan when the dog that my neighbour has is out, as he can see it through the fence. The other week I took him for a walk with my friend and her dog (who was also male) and I did notice the hairs on Tags' back standing up at first, but other than trying to sniff the other dog nothing much happened until we got down the road and something triggered one of the dogs to growl which resulted in a little scuffle between the two, but we soon calmed them both down and they were well behaved for the rest of the walk, my dog did continue to try and sniff my friends dog though.

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I'm trying to not drag this on, but I feel its best to provide as much information as possible. I've been browsing puppies for a while and I have completely fell in love with miniature dachshund puppies, but we feel a bit anxious about looking into bringing one home because we feel like Tags wouldn't like it, and think he may try and harm the puppy, so my question is, what is the best way to introduce a new puppy to an adult dog who has been the only dog in the house for 12 years and has little experience of being with other dogs, any help would be appreciated! Thankyou.


BTW, if we did bring a new puppy home, it would be a male dog.