This is a picture I did for my aunt (the same one I did the house drawings for) of her dog George. He was put down a few summers ago at a very old age. I took the picture for which this drawing is based on the last time I saw him. He was a golden retriever, and at the time of the photo, his muzzle was quite white, being so old. I've gotten pretty good at drawing dogs and cats in charcoal. I used several different kinds of it: compressed (my teachers would be scolding me), vine, and charcoal pencil. The compressed is great for those really dark areas, like the mouth and places with hard shadows. The vine charcoal is good to lay down as a base when you are first starting the drawing. It can be erased easily and provides nice light values. And the charcoal pencil is good for bringing out details in the fur and around the eyes and mouth. The best thing for highlights is your eraser. I used a kneaded eraser and a white rubber eraser. You can just lift off the charcoal to help give the illusion of shine on the fur. For this kind of drawing, your eraser is your best friend. I sole reason I enjoy doing these types of drawings is because of the reaction and appreciation you get from pet owners. They love seeing their animals immortalized on paper.