Here photo of this dog.

For convenience we will draw a circle, we will halve the vertical line, the horizontal average line is the middle and it will be the beginnings of a nose, slightly above it there is a line of eyes, divide each half into 5 equal parts.

Now we will draw eyes and a nose of a dog.

Let's trace a muzzle and wrinkles.

We draw a shape of the head of a bullmastiff, fish soup, about eyes border of a dark color.

It is possible to finish part of a body still.

I did not begin to paint it if you wish are able to do it. There is a lesson on realistic drawing of short-haired wool.