Above is a photograph of an illustrated page from Ptolemy’s Almagest, first written in 150CE, although this copy was clearly produced much later!
It depicts the constellations of canis major and canis minor and apparently served as an astronomer’s and astrologist’s guide book.
It was first translated in Latin in the 12th century (according the The Encyclopedia Britannica: https://www.britannica.com/topic/Almagest) but this particular manuscript appears to date from 1490CE, in Britain.
The dog on the left seems to be a form of sighthound, perhaps a greyhound or “vertragus”, the possible Celtic ancestor of modern grehounds, whippets, etc, owing to is short haired appearance (especially in contrast to the dog below), its short, folded ears, long back, and deep chest rising up to its narrowest point at the groin. (If you disagree please let me know in the comments!)
The dog on the right appears, to me at least, to be spaniel breed, with long floppy ears, a shorter body and a feathered, hairy tail.
Note the apparent lack of castration in dogs, as both have very prominent plums!!!
Hünemörder, Christian (Hamburg), “Vertragus”, in: Brill’s New Pauly, Antiquity volumes edited by: Hubert Cancik and , Helmuth Schneider. Consulted online on 13 June 2017 <http://dx.doi.org/10.1163/1574-9347_bnp_e12201960>