We once culled a newborn puppy because he had no opening . When we told the vet about it some time later he said we should have brought him in. Sometimes there is no opening in the outer layer of skin but they could be perfectly normal just inside. The vet could have created an opening. Too late for the pup tho, I was very sad that I didn't take to the vet first and show him. I would think this could happen to any animal.