Mike J said:
The smartest dog I have had was an Australian Shepard mix. I don't own stock so I did not use him to work but he was very intelligent. He just didn't necessarily want to do what you wanted unless it involved food. He was the most food obsessed animal I have ever seen. Sadly we had him put down Monday but 16 years is a pretty good run for a dog.
You have no idea what a food obsessed dog is until you have a Labrador Retriever...
My yellow Lab will try to eat most anything...including carrots, tomatoes, celery, peaches, etc.
My black Lab(litter mates) is a very finicky eater...he has to lick everything before he takes it, then drops it on the floor before he decides if it is suitable. Most times when he drops something, the yellow Lab swoops in and steals it.