The health problem has little or nothing to do with the show. It is the breeders or the ones that call themselves breeders. The pedigree on my dogs has a long pedigree that goes back many generations. Also, many of those dogs have been health checked for genetic defects. So yes you can have 13th and more generations of dogs that are not unhealthy and still maintain the function. health problem are due to a lack of selective breeding and too much inbreeding. There is no perfect dog. All dogs have some type of fault. The closer the inbreeding the more you double up on those faults. It has been mentioned that of a dog didn't work or of a dog wasn't of standard those dogs were eliminated from the gen pool. A responsible breeder should do the same. But the puppy peddlers and backyard breeders will put any 2 dogs together. Many do not even know or care what the standards are. They don't know anything about health issues. They will breed a blind dog, cow hocked dog, etc. They breed dogs with rare or exotic colors. They will breed dogs of different breed and claim that they are the same breed. I recently saw on world pedigree dog canario site a dog and some of its offspring since they put picture of the dogs if you have them with the pedigree. This one dog was almost all white. That is a disqualifying fault for a presa. That is an indication that that dog was not a presa. It has been mixed with something. Then in the offspring that were pictured they all have too much white in them. The pedigree on the first dog is not even a 3 generation pedigree. Unfortunately the many people that will purchase one of these dogs will not know that these dogs are not of standard. They will think they have something rare or more special. These dogs might in themselves be great dogs. But they should not be registered to breed as a pedigree dog. It is doubtful that anyone will know what health issues might be passed through the line that are in other dogs in their pedigree. If the breed registry would have required a picture to be registered or DNA testing those dogs would not have been able to be registered. The only time that I have had to submit a picture of my dogs to register them was when I took an FCI dog or other registry dog and registered the with a different registry. I have not registered my current dogs with AKC. But I have considered doing it even though they can only be registered AKC FSS.
In regard to the "Show" changing a dog. I understand what is being said. I agree and I disagree. Yes it changes the dog. But it is not the show so to speak. Any training changes the dog. This is true no matter what type of training is done with the dogs. That can be basic obedience, Conformation, Rally, herding, Boar Catching, Protection, Weight Pulling, Agility, Fly Ball, etc. That is the environmental stimuli. Dogs know how to sit, down and walk without human interaction. We teach them to perform those task at our discretion. Without this they would be wild and do whatever it wants. We teach them to live under our rule set. We teach them to allow stranger to examine them (touch their bodies, testicles and look at their teeth). This is just like the elephant that when it was a calf it is tied to a stake with a huge chain to prevent it from going any further than the chain. Then when it becomes an adult is tied to a pole with a rope. The elephant is still powerful enough to walk away regardless of the rope. But it has been trained or conditioned to stop at the end of the rope. The training does not change its genetic make up. It has been taught to follow human rules. My dogs would pull me all over the place if I didn't teach them to walk at my side when I want them too. In fact most would reject the leash and or collar. They had to be conditioned to accept them and to comply with my rules. So yes the "Show"changes them. They must be conditioned for it. I do notice a difference in the "Show" in the USA than in the "Show" in Europe. A dog can still be a dog in Europe. If a dog or a person gets too close in Europe they will bark and growl. Basically the dogs is being protective. The dog will not be disqualified. In fact the judges appear to like this as they know the dog is a guardian. In the USA in AKC or UKC they can and some judges will disqualify the dog for doing this. The dog can even be banned and you can't register any of your litters from that dog. I read that they can send a notice to those that have a pup from that dog that those dogs are no longer registered dogs. It is at the judges discretion. Some judges don't like to do it. I was told it is a lot of paperwork when they do that. Some judge are quick to do it. But when we have the FCI judges it is much different. I saw several dogs that attempted to bite the judge. Some were out of control. One that tried to bite the judge then refused to walk around the ring to show its gait. The judge award that dog 1st place and the out of control dogs got first place. In the written critique it mentions the dogs drive. On dogs that have been trained to walk at heel the judge comment was a lack of drive.