Everyone at my office has these basic navy polos with the company logo on them. Thor is at the office almost as much as everyone else, so we feel he should have a "mascot" shirt of his own. I can provide a human-sized polo shirt with our (small) logo, and I imagine the neck buttons could go up his back, rather than his front... also, the logo could probably be cut out and sewn along the back of the shirt as necessary.
Anyone interested in making a custom polo for my boy? I'm very flexible on price. Let me know!