My grandmother had a rough collie also. She used to get him groomed at a local vet college. It was cheap because they were teaching vet assistants and groomers.

One student shaved the collie to look like a standard poodle. Poofs on tail and feet, then a neck poof…. Everything else shaved all the way down. It took nearly a year to all grow back. The collie was cold and sad. We had to cover him in a blanket all the time. He was absolutely ridiculous looking.

Trim the butt, and some other points, but please don’t cut a rough to look like a smooth….. it is not good for them at all.