The white, long-haired Chihuahua puppy is recovering at an animal foster home with a cast on its left hind leg after suffering a fracture and torn ligaments.
Surveillance video at the Nuevo Water Company in Riverside caught 67-year-old David Hendershot with his grandson and the puppy.
Employees say he hit the boy and then threw the puppy to the floor. The district attorney's office is reviewing the case and could file charges.