I give this activity a B+. Older kids will have better luck getting clean prints. It's very important that you have the kind of dogs who allow children to grab, pat, and play with their limbs as long as the child is gentle, and you are observant. Our dogs are great. They have been with us since before Caden was born. If you're dogs are aggressive to any degree, DO NOT try this with your children. Make this an adult craft in order to remember your precious fur babies long after they've passed. I wish I had thought of this before my cat of 15 years passed last year.
Note: I wrote on the prints with "Sharpie" while the clay was dry. We used Crayola brand modeling clay.