Q. My 2-year-old corgi, Neo, loves a tummy scratch. Why is it that his leg shakes like crazy when I give him a tummy scratch? When I was a kid, my mom used to say that it was not a good thing. So instead, I give my dog a gentle tummy rub and his leg remains still. What is your recommendation? —Andy Quittmeyer

A. Andy, let's just get this straight right off the bat:

I LOVE dogs.

I have a 6-year-old chow-corgi mix named Corky, and he is the best person I know: Smartest, most decent and most laid-back (except when he sees a squirrel).

If it were up to me, we could just sniff around dog topics all day long. In fact, I like how dogs smell. Gimme the smell of a good, healthy dog over too much perfume any day. Ya know another thing I like about dogs? You can drop food, and they'll just take care of it right away. If I didn't have Corky, I'd have to eat a whole lot more carefully. But I do have him, so we can both just snack away on a big sub sandwich while watching the ballgame.

(That's just a real happy image right there.) What you're talking about is called a "scratch reflex." Dianne Dunning, director of the Animal Welfare, Ethics and Public Policy Program at North Carolina State University, explains that it's somewhat similar to our reflex to pull our hand back from a hot stove.

Here's how it works: You scratch your dog's belly, and sensory fibers on his skin alert the dorsal nerve root, which sends signals up the spinal cord to the brain. The brain then says, "Bug on the belly! Git scratchin'!" And your dog's leg starts kickin'. The reflex is there to help keep him free from fleas and ticks and other irritants.

Now, my recommendation on your mom. I would not scratch her tummy, even if it's fun to watch her leg kick like crazy. Sure it's good for a laugh. But it's disrespectful. Be a good son. Call your mom and buy her a nice card now and then.

It doesn't hurt your dog to scratch his belly and get his knee kicking. It might bug him a little. It'd be a little like having someone tap your knee repeatedly, triggering the reflex that makes your leg jump. In fact, vets who suspect spinal or neck damage in dogs sometimes use the scratch reflex as a diagnostic tool.