Can't change dog size in CAP?

I'm not sure if this it how it would work in game, but what if you had your dog breed with another big dog from the breed mixer? you should be able to eventually get the right markings and stuff, if the CAP livestream still holds today.
Also, does the paint go away when you select a different breed? Because if it doesn't, you can select the new breed and find his old coat in the patterns section, I think.