I am working on a couple of pieces for a juried B&W photography competition and the deadline is this Friday! After checking out the previous years winners it was apparent that they seem to like contrasty images. To achieve this you need to have a true black in your image and almost 100% white. This is tricky because you don't want to have your highlights blown out and losing the details. That means they want to see all the little hairs in the white mane and also the subtle detail in the shadows.
The upper picture is close to finished. The lower picture was also worked up in B&W but sepia toned to get the brown color. I left the pink in his muzzle while accentuating the blue gray. I think I like this workup better but unfortunately the contest is traditional B&W!