Don't know what her mix is to be honest. Possibly a bit of Jack Russell, or so they thought at Bothwell Bridge when I got her. Sheds hair all the time and has awful plaque if her teeth are not brushed regularly.
Possibly some collie as she does the lying flat and then running up to dogs thing! But only that occasionally, as she is very selective who she approaches and can be a bit of a loner.
She does like male collies, so perhaps in her past a collie figured somewhere. Who knows! What I do know is that she is just the best dog since sliced bread.