The agency has teamed up with Mountain View police to investigate the shooting, which is believed to have occurred near College Avenue during the first week of May.
A resident found the cat on May 7 suffering from gunshot wounds to its stomach and leg. Police said the female cat had been shot three times with a small-caliber handgun.
The animal, which is likely 2 or 3 years old, had to have one leg amputated, but is recovering and learning to walk on three legs. The suspect could face fines and time in prison on felony animal abuse charges, according to police.
The humane society is seeking donations to help pay for the cat's life-saving surgery as well as a home for the cat. Anyone who would like to donate money or adopt the cat is asked to call (650) 424-1901.
Anyone with information about the shooting can call police at (650) 903-6344.