"Sight hounds" refers to a specific type of hunting dog that relies primarily on their excellent eyesight to track and chase their prey. Full definition
They are an old European breed of sight hound used for chasing game in open areas, but intelligent, quiet and loyal enough for the castle. (fidouniverse.com)
They were originally bred as sight hounds to hunt the large prey that inhabited the harsh regions of Central and South Asia. (urbandognyc.com)
What would be a normal PCV in most dogs is abnormally low in greyhounds (and possibly other sight hounds as well?). (2ndchance.info)