Jose Luis Garcia Perez gained over 26 pounds for his role, mainly by eating cheesecake.
Bernardo's emotional final scene with his grandmother was caught in the first take. Director Miguel Albaledejo asked his young actor David Castillo to do a second take because a fly was buzzing around in the background but Castille refused as he was so emotionally drained by the scene. The fly was removed digitally.
The scenes shot at the fairground were actually filmed by Jose Luis Garcia Perez.
The Spanish title "Cachorro" literally translates as "puppy", "pup" or "cub".
This is an extension of a short film that Miguel Albaledejo made in 1996.