This sounds like it might be interesting:

On The National Geographic Channel tonight at 7:00 CT

Science of Dogs [TV-G]
Wednesday, August 15, 2007, at 08P
The dog is one of mankinds prolific creatures. With 400 breeds and counting, the dog is more varied in size and behavior than any other species on the planet. NGC looks at mans evolutionary manipulation of dogs appearance, talents and temperament and the accelerating efforts to create breeds to suit our needs (more than 80 percent of todays breeds did not exist 150 years ago).