Check with your vet. There's a canine version (ascriptin?) that may be better than the baby asprin.
The vet wanted me to cut back on Jake's two adult 325mg aspirins a day - due to concerns about stomach troubles - but said there was no point in baby aspirin. The vet insisted on buffered aspirin.
I tested and observed per the vet and Jake shows some slowness and stiffness in his caboose if I stop the aspirin. He'll get one each night.
I had prescription Metacam for Pancho but it's expensive and I don't think it works any better than aspirin. Sorta like prescription Celebrex vs. Naproxen (where the last story says over the counter Naproxen is safer.)