A class I malocclusion is just when the front teeth (between the canines) don't quite meet the way they're supposed to. It is presumed to be some combination of factors including environment, congenital, genetic, and dumb luck.
A class III malocclusion is when the mandible is just a little bit too long, and rather than the top teeth fitting nicely and prettily over the bottom, instead they either meet straight on (try it, you can see how it would hurt after a while) or have the "bulldog look". Class III's are considered to be a genetic skeletal deformity, where the pre-molars and molars are involved to some degree as well as the more obvious incisors.
(For reference, a class II is when the maxilla is waaay to long, and a class IV is severe skeletal deformities like where the teeth don't even meet in the front, or one side of the mandible is longer than the other.)
Dogs that are shown are typically in the highest demand for breeding and continuing the lines of the breed. As a result, they need to be the best genetics available, and breeding dogs with cranial skeletal deformities is not in anyone's best interest.
S's owner came to the dentistry clinic when she was about 6 months old. In hand, he had an article written by the AKC for judges about how to spot (and disqualify) dogs who have had orthodontic work to correct malocclusions. The article had a picture of a dog with an expansion device, which many people I know had as children in conjunction with their braces. The expansion devices angle the teeth outward appropriately so that the skeletal abnormalities are disguised and the dog has a normal bite.
He pointed to the device in the picture and said "I want that for my dog."
After many hours of ethical discussions amongst themselves and with the owners, my clinicians ultimately decided to use the expansion device to correct S's malocclusion and crossbite. The owner desires to show this dog, and insists that "no other dogs in the line have any teeth problems".
I have several major ethical issues with treating this dog and working with this owner, which I will briefly highlight, along with some pertinent facts.
1) The dog is in no pain and has no quality of life issues with her current bite.
2) The dog is an intact female that may be bred in the future, potentially to relatives.
3) The dog is intended as a show dog, and judges are clearly *taught* to look for these changes.
4) There is no real way for us to "report" this owner to the AKC.
5) In order to become board certified in veterinary dentistry, a resident must perform and document two orthodontic device fitting and placements.
Personally, I have decided to not treat an animal when placed in this situation. While I would be happy to place the device, I would do it on contingency of spaying the dog. As a student, I abide by the choices of my attending clinicians.