with animals that have long faces, like dogs, depth of field is going to be an issue in any shot like this, because of the distance from the eyes to the nose. The solution is to tilt the camera so as to align the lens with an imaginary line joining the nose to the centre of the forehead ... or stop the aperture right down, which would mean the background wasnt as blurred, and would probably be too slow for something living that wants to move about.