[Anonymous]

I had a dog like that (herding breed), had soft stools till the age of 9 months. Then it just stopped and she went about twice a day, an hour or two after eating.
A 3 to 5 mile brisk walk (1-2 hours) every day helped too.

I would take a look at the diet, as your vet suggested, also, you may find some helpful tips here http://www.homeovet.net/dynamic/php/downloads/dog-c8470f2c75dbe4b683205c3919ee2310/dog_diet_complete.pdf