I wholeheartedly echo the comments about TYPES rather than BREEDS ... I said a very similar thing on the Equestrian side of thing a while ago.

I wholeheartedly echo the comments about being unable to prove true pedigrees past c.200 years ago. (The Kennel Club is only just over 100 years old ... 1873)

For example ... the often stated case for the Wolfhounds ancestry ... about 150 years ago the breed died out. It was bred back by a Captain Graham (if I recall) using a mixture of breeds ... Deerhound (which he'd previously restored but more by pooling surviving dogs than cross-breeding), Great Dane, Tibetan Mastiff!! etc.

Geographical location is also important for most breeds ... but there was an international trade in the best ... the greyhounds for example from Britain.

If you're getting a dog for a medieval purpose ... think how they were used ... and by whom. If you want a sighthound ... you need two (today 2 hounds are properly called a "couple" (one is hald a couple) ... brace is a more recent term I think picked up from the gundog fraternity) and they are not a commoners dog ... but could be being looked after by a commoner in the sense that a Fewterer handled the greyhounds ...

Just like the horses and everything else ... social ranking ... your degree ... permeates society ... so a Deerhound couple (as the breed standard still says ... a large rough coated greyhound) bred to hunt Red Deer would be a possibility in the hands of a Fewterer of relatively low station, or someone of high station ... but not (for example) a merchant.