Dogs are one of the community animals, meaning they live together with other dogs and stay close among the pack. This is imprinted in their evolutionary program and is evident with the wolves. Given this fact, dogs can easily 'socialise' their way through the pack; however, when you put them in another pack where the hierarchy and the environment is totally different than the previous one, they tend to familiarise themselves first. And we are just talking about wild dogs getting in another pack. With all these domesticated dogs we have, it will be a little different for them being with other pets. However, there are some tricks that we could do in order to 'introduce' them to other pets.