Dwight Howard is mourning the loss of his beloved dog, Sunday ... saying his companion was tragically killed in an alleged hit-and-run over the weekend.
The NBA center shared the sad news with his Instagram followers on Wednesday, posting several photos and videos of the good times with his Belgian Malinois.
Howard -- now playing in the BIG3 league after 18 NBA seasons -- said Sunday lost her life on June 18th in Suwanee, Georgia, after she was allegedly struck by a car that didn't stop.