spinning dog.

[Ember]

 This is a bit of a frivolous question, but it has genuinely puzzled me for some time, why do dogs turn round and round and round before settling down, and also the same when they are out spending a penny of a more serious nature

[Cetti]

I read this years ago, but whether it's true or not....makes sense though...

It  stems  from the time before dogs were domesticated and made their beds in grass or reeds, so to make it all cosy and  flat they twirled round and round just to flatten it down. One of those built in instincts that has remained from long ago.

[trudileach]

'Cos one good turn deserves another!

[barbro]

Dogs turn round and round ,as they would have done in antcient times,in the wild,to flattend the grass in order to make a comfortable place to rest on.

Same for the "penny" spending in order to leave scent.