[anonymously]

I no longer use a lot of supplements. I do add a fish oil capsule once a day to meals, I add water to the food, especially a senior male small breed, as they are vulnerable to developing bladder stones, UTIs, take out frequently to urinate….at least every 4 hours.
Exercise/long walks as tolerated.
If you are feeding a decent diet, they don’t need multi-vits….unless your vet has recommended such. The liver has to detoxify all this stuff.
I’m just sharing what I have learned over the years.
BTW: shih-tzu’s have lousy teeth, if the vet that examines your dog recommends a cleaning and extractions, I would get it done. Then daily brushings (see YouTube for how to videos) may help to prevent any more professional cleanings being needed.
My dogs do well on Nutrisca salmon and chickpea (canned and dry) as a base. I often add a tablespoon of cooked chicken or lean meat or scrambled egg…you get the idea.
http://skeptvet.com/Blog/?s=supplements