@Rebel - Full blood workup including full Thyroid panel (full panel no just what the normal vet workup that is not a full thyroid panel)... as they say make sure that he is in good health. Also what are you feeding him? How much total are you feeding a day? Also with reducing food, add veggies to his food to fill his belly... green beans are good to use... I use Cauliflower and Broccoli... Note also that low normal is typically too low for Basenjis.
To give you an idea of the contrast between Basenjis and Border Collies, my BC once spit out a pill, I said "Blackie" in a disapproving tone, and he picked it up from the floor and swallowed it!