–Since Shih Tzu do not eat all that much, every bite counts. You’ll want to avoid kibble that has high grain content or any sort of fillers.
Just some of the 1 (very bad) through 3 (just ‘okay’) starred brands as graded by Dog Food Advisor
Alpo, Back to Basics (grain free dry), Ben's Best, Beneful, Blue Buffalo Basics, Caliber, Country Acres, Defender, Everpet, Evolution Diet, Good Sense, Heartland Reserve, Gravy Train, Hi-Point, Hill's (some of the Ideal Balance and some of the Science Diet formulas),... yes, the list is still going...and, this is just a partial list...
Iams, Jake's Choice, Kal Kan, Kibbles 'n Bits, Natural Balance (original), Ol' Roy, Old Glory, Old Yeller, Pedigree, Purina, Racheal Ray (Nutrish dry and some others), Royal Canin (Lifestyle Health and some others), Simply Right, Sonny's Pride, and Trader Joe's (dry).