I've always rather enjoyed drawing dogs. They're aesthetic creatures; strong, bold, and always alert. Cats, however, usually make bad drawings/paintings. They tend to be cute, fluffy, and usually asleep (I know our Freddie won't mind me saying this).
This particular dog (above) was called 'Hardy', and he was a big lad. He was possibly a Great Dane or a Great Dane cross. His wealthy lady owner had to struggle to hold him still whilst I rushed at this drawing. For the finished job I used the outline of the drawing, plus the positioning of his eye, nose, ear, etc, then looked at photos in a dog book for some of the finer details (yes, I cheated).
I also had to paint his name on the picture; his owner's house was filled with such paintings, all with their names in the same sized gold typeface (the things we do for money!).
If only digital photography had been around in those days, it would have been so much easier to get the details spot-on. Nowadays, thankfully, there's little call for such work; I would refuse it anyway.