As much as i'd like to believe it I have to say no. Although they do have a purpose, after all God made them. Idk they are great companions, they know us, they love us unconditionally, they're there when we need them & even when we don't, they're our best friend, I think it's safe to say we need them more than they need us. Therefore, we might say they are "like" angels always looking after us.
I'd like to believe they have souls though & are here on a mission kind of like if they do well here on earth they will make it to a higher level of existence. But not angels. Angels are not made up of flesh just spirits & they do occasionally disguise themselves as people, but only for a brief encounter. Not a lifetime.
I would have to say that dogs are always there for us, and that they love you unconditionally. While they may not be angels here on earth, I do believe that after they pass on, they do go to heaven and be with god. As for dogs that attack, it is not their fault, they have been trained to be that way. I know a dog who is a pitbull/boxer mix who belongs to a good family and she is the sweetest dog alive!!
Not an Angel, but they match the definition of Guardian Angel:
1. an angel believed to protect a particular person, as from danger or error. 2.a person who looks after or is concerned with the welfare of another.
The bible was something re-written by the hand and words of men many times over, how can the bible constantly be negative towards dogs, when in fact dogs were the one creature on this earth that helped humans the most, dogs and men in theory have been partners for 14000 years.
How many dogs have saved lives, they have been used in law enforcement, military, hunting, service dogs, help the blind etc etc etc. Name another creature that does that (I don't see cats leading the blind).
I believe dogs are the forgotten true Guardian Angels of man, because of everything on earth that I know; only they come close to anything that I view as a guardian angel.
Dogs has murdered humans yes, but humans have murdered humans, you cant label all dogs evil unless you label all humans evil.