if you go by the hindu philosophy every living thing has or is part of a soul!
i have always had dogs with me and just like anyone else i love them. they behave more or less like us.
all i can tell you is they are truly soulful companions. a day in our lives is not complete if we dont get to stroke a dog's head or play with it. It understands our moods and can feel our pain. it can lift us up from the depths of despair to the apex of happiness.
i am sure they do.
I am sure also. I have told more of my personal feelings and secrets to my dogs as we sit and talk than I ever have told to humans. I feel that they listen with their hearts and listen without judgment until I am through. Their presence is reassuring and I have often told my smaller ones, as I put them on my lap, "I need the lap time, even if you don't."
As for every living thing having or being part of a soul, I find it immensely satisfying that we should all be part of Mother Earth's - Gaia's - consciousness. Someday, perhaps if we ever become more enlightened, humanity will look back with shame that we had so much evidence of that and continued to ignore it.