A lot of times I get people who say, "I want my dog to like everyone he meets!" And, people tend to look at me like I have three heads when I reply, "Why? Do you like everyone?"
All dogs are individuals. They each have a unique personality and just like humans, sometimes those personalities clash. We have to step back and not look at breed standards or what we expect out of a dog, and instead; look at what the dog is capable of. If you had a dog who was shy would you pair him with a dog who was over the top and always in your shy dog's face? Probably not! But, what if your shy dog started to come out of his shell more because of the other dog being so over the top? It is up to your dog and what he/she will accept.
You can also make the transition of a new dog coming into your home a lot smoother by using a shutdown protocol. Imagine, you come from one home, to a rescue and into another new home. That would be pretty confusing. I know I would feel shuffled and unsure if it was me. Sometimes, people complain that the shutdown is unfair to the dog. A dog in the first two weeks needs time to shake off the stress and start to adapt. By using the kennel and not just tossing two dogs together, it's a much easier process.
Now, what do you do if your dog truly just freaks out around other dogs? I like to ask questions about the environment the dogs were introduced in. Was it a tight confined, place? Was the dog on a tight leash? Was there somewhere open that they can meet? Was it a nose-on-nose meeting? My number one question is: If the dog had to choose between flight or fight, did he/she have enough space for flight?
Now if your dog is just dog aggressive, there are still options. I live with a dog aggressive dog, and he has playmates. They are carefully selected playmates whom he gets along with. They all play well with him and surprisingly enough, their personalities range all over the place. We took a lot of time selecting his playmates and it was a very slow process.
There is also BAT (created by Grisha Stewart) and I use it not just with Grey, but also with a few clients. I use this is conjunction with a focus program and have seen first hand how a dog can self soothe as well as focus on me as I remove them from the potential of a dangerous situation.
So, in short, there are options and I never like to deprive a dog from playing with another dog, but if my dog doesn't like your dog, I'm perfectly fine with that!
The picture is Spudz. He has taught me that having only a handful of playmates is A-okay!