I've seen it with sheep, too: photos of each individual lamb. Especially with rare breeds that come in many colors and with many kinds of markings.
And I definitely see it with horses.
And with some kinds of pigs.
So I would say that photographing each individual animal is fairly common, for quite a few kinds of animals.
Of course I would not want anyone to get a puppy that does not have the right temperament for them, but I can easily understand wanting a dog that has attractive color/markings AND the right temperament. And what color & markings are attractive varies depending on the person, so photos are helpful.