yes, if he had been hurting i wold expect to see his ears drop, a flinch away from my hand, his head snapping around to point at my hand when i hit the sore-spot, and such reactions; sitting abruptly, tucking tail or butt, spinning the sore-side away, etc.
if he did not react + i found no knots or warm-lumps radiating heat, then i would just watch his urine stream carefully for any sign of pink; bruised kidneys, etc, color the urine.
i would make a statement only so that they have a description + an area; then when he repeats his rotten abuse, they have prior complaints. WRITE down as much detail as U can recall, + take it along with U; if U think of other things, U can add them as they pop into Ur mind - any odd details, height, skin color, beard, glasses, tattoo, clothes, hat?, anything.
i hope they grab the rotter.

and i hope Ur pup is fine, no behavioral-impact + healthy!
cheers,
--- terry