This is a question that we often get from sitter and owners who work with Rover. Help the community out by answering them in our forum!
Your pup could have run into a stray or neighborhood cat while playing in the backyard and maybe the cat peed on him/her...which I've never personally seen, but definitely possible. Your pup also could have just rolled in fresh cat pee. Regardless of the cause, the answer is a bath!
Can you provide more details of the timeline of your concern? Is this a sudden change? One time issue? Ongoing?
And, laughably, I must also ask if you own cats. Haha.
Free-range cats can be quite adept at entering your yard and leaving trails, so that is also a possibility that comes to mind.