I only shave from armpits to sanitary if the dog get matted there easily from wearing clothes or a harness. Usually when grooming a dog I'll trim the chest and belly above the sanitary area with the same blade I used on the body except in the refer direction of the hair growth so that its a little shorter then the rest. Easiest way to do this is pick up their front legs so they are standing on their rear and clip from sanitary straight up the belly to the chest (usually you go with the direction of growth so that would be from chest to sanitary, but to make it shorter you want to go in reverse).
__________________ Kellie  and  Morgan |