Well?
I’ve known many dozens of dogs and can’t say I’ve ever observed one spin around before defecating.
You know “defecate” means “take a shit” and not “go to sleep,” right? 
Yes, I know what defecate means. My dog spins before shitting all the time. I see many dogs do this at the dog park.
Both of my dogs do this, the rarely spin before sleeping, and this is the first thread I ever subscribed to before I posted.
Spin sounds a bit fast to me, but my dog definitely makes tight little circles in the grass before pooping.
From some website:
I do the Wonder Woman spin before taking a dump.
Makes me feel pretty.
You’ve been deprived!
I’ve owned a zillion dogs (Australian herding dogs, black and golden labs, English bulldogs, American bulldogs, Pugs, and mutts) and every single one of them did the spin waltz before taking a dump. It’s adorable and mysterious.
“This is my spot! Admire my graceful dance of possession!” <poop>
They’re utilizing centrifugal force so the poop comes out more easily.
I thought of this the other day when my dog defecated after it snowed. His spinning patted down the snow. The snow pat down was just so perfect. The snow would have hit his ass if he had not done the spinning. Made me wonder if there was a connection, but he does it in the summer, too.
I hurt a rib reading this thread, laughing and all. Who do I sue?
This is my feeling. My dogs have vulnerable body language when they do this, looking to me as the pack leader for a signal that they are OK. They tend to move off the spot quickly too when done so as to not be a sitting target so to speak.
That seems more like marking with peeing, which my dogs will do with what must be urine measured in molecules.
Did the Australian dogs spin around in the opposite direction?
It may be a little dog thing. I’ve had big dogs for decades, probably 50 dogs in that time, and the only dogs I’ve seen spin before pooping are toys. I’ve seen dogs of all sizes spin before piddling, but only seen toys spin before pooping.
I remember reading some article some time ago saying basically the same thing, they do it also in the summer to flatten down any long grass that may be around them.
Of course, today there’s often not much long grass around but they still have the instinct to spin around.
We covered this in one of our physics classes…
Centripetal (centrifigugal?) forces? Or was it the Coriolis force? Do dogs down under spin the other way before dropping a load?
I forget.
I always figured this was the case, and the same thing for grass. Would you want grass tickling your tuckus while you’re doing your business?
Neither of our dogs spin before pooping, but they both pace back and forth over a space of about 20 feet several times. Now that I think about it, the younger dog didn’t do this originally and seems to have picked it up from the older one.
Because one good turn deserves another.