It really depends on what it does to the outline of the dog. It isn't technically a fault but some markings can create optical illusions that can be a detriment to the dog. That is the reason for wanting to see a stacked pic. It would show what the overall impression of the dog is with the marking.
This really isn't any big deal.
Seen much more white over the shoulders and up the legs.
If the dog is conformationally a good dog, this marking isn't going to make a difference.
But, you would have to take into account it is black, and if you haven't shown before, then having a novice handler, black dog, and lots of white are some big strikes against the dog.
I have shown a few dogs with more white.
Personally, I have no issues with it… but the dog would have to be so nice conformationally, that I would even put my money into showing it.
My bloodlines have more white than I personally like to have on a dog, but color/markings are not something I look at when grading a litter.
Do you mind mentioning where you got your puppy and the names of the parents [sire/dam]?
Best of luck with your pup.
This is actually one of our puppies from this year. We aren't going to be showing this one but one of our other puppies. I was only asking the question because I had not seen any marked like this one. Oscar is going to a home as a pet. The sire is "Black Devil of the Congo CLG" and the dam is "Miss Sweetpea of the Congo CLG". The names were not chosen by us so we did not give them "of the Congo"! This puppy has a great disposition, just like his sire.