I got these raincoats for Lion and Penny when I was in Washington, at a pet store called Mud Bay. They have a strap around the front and a strap around the belly.. They also come in a little pouch that you can attach to the leash. I couldn't get very good photos because they did not want to move around in them, so here is what it looks like from the side:
RC pets poncho
You is really gonna make me wear dis? It isn't even waining.
Mama, I tink dis is a wittle big.
I is gonna stand here until you take this off. I is serious.