ajshep the hip score you should be looking for is low and even i.e 3:3 unless of course a dog has sustained an injury which could give a reading of for example 3:15 which seems way off the mark but can be accounted for and therefore doesnt signify HD.
I have a friend with a Rott who got him from good hip scored parents and he has a combined score of over 50!!!! So the system isnt fool proof
