I found out that there is a much less expensive, human generic for Metacam, called Meloxicam (thank you to a member of this forum!! :W). It comes in a tiny tablet. I got a prescription from my vet that I had filled at my pharmacist. 30 tablets cost just under $10, and Jackson (63 lb.) only gets 1/2 tablet a day! I just hide it in a bit of canned dog food, which he happily gulps down.
For a Shih-tsu, it's probably not doable, because the tablet can't be cut small enough for a safe dosage, but it works great for larger dogs, for a LOT less money.