I have a litter of 7 pups that are 5 months old. At 4 months 6 out of the seven had blister appear on their shoulders about 1 in. From top of shoulder. Some on both sides , some on one side. The blisters scabbed over pealed off and now have no hair growing back. The scars about the size of nickel to quarter. Never seen this , any ideas?

Thanks, It healed up on its on. I was just wondering what it was.