My sable collie is 12 months old and weighs between 25-30lbs. He looks very skinny, but seems to eat well,is active, and has a beautiful coat. He lives outside on our six acre fenced in residence. We recently gave him a 3 day treatment of over the counter worm medicine, because I thought maybe he had worms and that was the reason he was skinny plus it had been probably 7 months since he had taken any worm medicine. We had a female collie that passed away last year (was hit by a car) that was 12 years old and weighed about 60lbs. so I guess maybe I'm trying to compare what I think he should look like.

My sable collie is 12 months old and weighs between 25-30lbs. He looks very skinny, but seems to eat well,is active, and has a beautiful coat. He lives outside on our six acre fenced in residence. We recently gave him a 3 day treatment of over the counter worm medicine, because I thought maybe he had worms and that was the reason he was skinny plus it had been probably 7 months since he had taken any worm medicine. We had a female collie that passed away last year (was hit by a car) that was 12 years old and weighed about 60lbs., so I guess maybe I'm trying to compare what I think he should look like.
Ask a vet. Sounds simple, maybe even patronizing, but the vet can tell you more then most bloggers can. Call a vet's office by finding a number online if you live to far away from one to go yourself.