Advantix Makes Dogs “Ticklish”?

I’d like to interrupt the ongoing discussion of how we’re in the early chapters of The Stand for a quick question about what really matters: the cute behaviors of my dog.

There’s probably a technical term for that thing dogs do where their back legs twitch when you scratch them in just the right spot. I’m not sure what it would be, though– Kate and I tend to use “reflex arc” as a shorthand, but when I was a kid it was described to me as the equivalent of tickling a dog, so I tend to think of it that way.

Anyway, we give Emmy Advantix as a flea and tick preventative, which works really well. We’ve noticed something odd, though: after we apply the Advantix every month (it goes on the skin along her back– we usually bribe her to hold still for the procedure with the chewy beef-flavored heartworm preventative, which she loves), she’s much more sensitive to the “tickling” effect. To the point that if I scratch her back in the right spot, she’ll do the leg twitch thing even when she’s standing up.

So, what’s the deal, here? Why does the Advantix make her so much more “ticklish”? It doesn’t seem to distress her at all (God knows, it would freak me out), and the effect usually goes away after a week or so. It’s very definitely correlated with the Advantix, too.