the same is happening here regards size but i think here its because of the influnce of coarsing sirse put to track bitches to add size and stamina
now and again you get a small dog"never give up" 66lbs but was a machine on the track i breed to him pups 12 months this week gone the dog is 74lbs and the bitch 68lbs the dam was 60lbs you do get some lines here that throw small off spring but very few now and anybody with that type of brood usually looks for a bigger sire
as here the first bend is the making or breaking of your race chances so early pace and power are important