Dogs in oil paintings, work very well. Oil paint has a substance to it, which is very suited to dogs, especially their eyes, open jaws and noses.
One can convey a real wetness of such parts not equaled by watercolour. As these are portraits, life is paramount in the eyes and that is where we look most at our pets.

I have painted many breeds, such as Labradors, Retrievers, Yorkshire Terriers, German Shepherds, Beagles, Dachshunds, Boxers, Shih Tzu, Schauzers, Bulldogs, Pugs, Cocker Spaniels, Rottweilers, Doberman Pinschers, Gorgis, Great Danes, Huskies, Springer Spaniels, Collies, Whippets, Greyhounds, Bull Terriers, Chow Chows, Old English Sheepdogs, Russell Terriers, Setters and more.