] Called Neutersol, it's a shot administered directly into ] the testicles of puppies at the right age for neutering. ] The ingredients -- the amino acid l-arginine and a zinc ] salt -- cause the testicles and prostate to atrophy. ] ] The alternative, surgically removing the testicles, ] guarantees sterility. In a study of 224 dogs, Neutersol ] did almost as well: Semen analysis showed only one ] sterilization failure, said Dr. Melanie Burson of the ] Food and Drug Administration. |