The current post however contains the gem:
"I honestly cannot think of a single time I've seen navicular in a horse with a
great shoulder and a long, sweeping stride."
It would be nice if conformation were that easy, and you could just blame straight shoulders, end of story, but in reality horses with HUGE strides and great movement (I am thinking especially of Ghost and Dexter who both have classic laid back shoulders and enormous overtracking strides) can get "navicular" - actually DDFT if we are being accurate - just as badly as any other horse.
By contrast, you can have a horse like Felix with a fairly upright shoulder who is as sound as a pound and very light on his feet. He has a bouncier stride, and will never have the over-track of Ghost or Dex, but he is more compact and agile as well.
Its more to do with hoof health than straight shoulders, I am pretty confident about that :-)