I honestly have not looked this up to see if its okay for dogs, because I'm lazy, but I know that papaya is good for heartburn/acid reflux in humans. In fact, we recommend it to the pregnant mommies at the birth center I worked at instead of Roland's or tums. It definitely tastes better.
Maybe you could research and then ask your vet???
Edited to add: I looked it up and this is what I found..
http://canigivemydog.com/papaya
It says papaya is safe and can cure digestive issues as well as help in other areas.