You could be on to something there about Collies putting up with much more from their own breed there is a rather grumpy female Collie who goes in the park, even the owner says she won't mix she doesn't like other dogs, but Betty was fascinated with her and kept going up trying to make friends, and she won her over in the end and now the other Collie is really pleased to see Betty and is also fine with Brinley.But although Betty likes other dogs she is mainly friendly with the little dogs in the park, and has never befriended a bigger dog before, so I think there is something about Collies liking each other!