Great Danes and Mastiffs are not difficult to shoot, as they tend to be pretty laid back. The small dogs are either super easy(like the chihuahua and the shi tzu pictured) or so difficult you pray for a couple of good shots.

With the big dogs, you just need longer backdrops or a different place to sit. My table was made for St Bernards, but, not all large dogs are comfortable on a table. I did have full sized collies(100+lbs) on my table, but, they were trained to a grooming table.