do all dogs have that itchy spot?
 

Every dog I've scratched.. it seems like they have a so-called "itchy spot", where their legs start flailing about wildly as I scratch them there. What is it about that particular spot?

My dog doesn't.

Out of the three dogs I've had, none of them have ever had the itchy spot.

Weeeeeeeeeeeird.

http://www.askmehelpdesk.com/dogs/it...ck-269081.html
Most dogs have certain spots on their body where if you scratch, their leg(s) will move involuntarily. This is most like because you are stimulating a nerve which then somehow transmits an impulse to the leg(s), which respond by moving involuntarily. It has nothing to do with the dog actually being itchy or needing to scratch itself.