When the puppy gets his adult teeth, the mouth should be checked for structure of the jaw and dentition, a puppy which has an incorrect bite (undershot, overshot, wry) should be excluded from any breeding plans you may have had. Faults such as these are contrary to the breed standard and once bred in are very difficult to breed out again.
Overshot and undershot bites (however small) is a disqualification in the show world, just like any noise in a field trial with prove instant dismissal, so in the show world no dog would even get past the first showing with this fault, so no champions would carry it. Which in my opinion is maybe one of the only good things about show cockers.
At present many of our Working dogs seem to be obtaining and carrying this trait. Here are a few problems besides many. 1) Not only if the condition is bad enough, the dog cannot do the job it was meant to do properly, 2) It could have problems with eating, 3) It is most undesirable to look at. 4) Uncomfortable for the dog. Full dentition is important to strong jaw structure that is necessary in a working and hunting breed that must retrieve both waterfowl and upland game.
Stud dogs or breeding bitches which carry this trait is a no no. These dogs should not be bred from and even spayed or neutered. A good breeder would never breed, as further down the lines it will come out in puppies, unfortunately this seems to be happening at an alarming rate.
When I use any stud dog, one of my main priorities is to carefully examine the mouth, this also goes for checking the breeding bitch if buying puppies. Before you even decide on your stud dog, call the owner and ask the owner if the stud has an overshot or undershot mouth, this may save you a long journey or missing your bitches due date if you decide not to use the stud once this fault becomes apparent.
Nine week old puppy, Shows
a correct scissors bite on an adult