
Buy either rice flower or potato flour. Mush a can of pilchards in tomato sauce in a bowl add a few tablespoons of water. Add enough flour so you have a dough you can roll into balls. Make golf ball size (or slightly smaller) balls, press down lightly and back on a baking sheet for 15-20 minutes at 180.
If you have a food processor you can whir anything edible by dogs into a moist paste and rreplace the pilchards with it. And actually, anything that mixes well with the flour is fine.