Instead of putting boots on her back feet, how about putting a little t-shirt on her to cover the incision site?

We had a cat with a skin condition and we had to stop him scratching his chest. I bought a babygro-type thing and cut the legs off. Then I simply put it on him, using the arms for his forelegs and the body part of the babygro covered his back and stomach. He looked rather mad, but it worked!

Hope your lass is better soon.