He is a mulitple mix, I know there are a few borzoi's around but not enough that I would pick saluki or borzoi,and an actual wolfhound is even rarer, as the sighthound possible mix I would say greyhound some breeders will adopt them out privately without having them fixed first so that may be where the arched back comes from. I do believe he has some border collie and without knowing the height or weight and no reference in the picture , it is hard to say what else he may be mix with though Dane is a good possibility or some hound mix