|I've been told that it's dangerous for Border Collies to swim because they will sink if they get into a semi-vertical position. It has something to do with their narrow chests. If they get too upright, they can flounder and sink like a rock. Have you ever heard of this before?|
As far as Border Collies not being able to swim if caught in a vertical position and sinking like a rock, in my opinion, this is pure whimsy. I have never heard of a Border Collie drowning (though I am sure there have been some but I bet they were not normal circumstances) and I know countless that can swim for twenty minutes at a time around and around a lake after ducks. They can swim circles around most people. There are Border Collies that are trained as water rescue dogs - some dive to the depths of lakes in search of corpses and drowning victims - and some leap from helicopters into water in search and rescue missions. I can't think of any reason why a narrow chested dog would sink in the vertical position. Yes, they may sink faster than in a horizontal position, but like a person, can easily shift position and swim to the surface.
In fact, what bothers me about this is the idea that some people would be so cautious as to not allow their dogs to swim in deeper waters. There is no better exercise for a Border Collie (other than chasing sheep) - it is great cardiovascular work, nonstressful on joints and growing bones, and burns tons of calories. Even to dissuade a Border Collie from swimming would be doing it a disservice. Besides, they generally love it (yeah, I know.. some don't). But those that want to swim, let 'em at it. (The idea of a life preserver in fast-moving waters or out to sea is a good idea but probably overprotective and unnecessary when it comes to most swimming activites).