The testicle on the left has cancer. The one on the right is unusually small because the cancerous one was producing so much testosterone that the other one shut down and shrank. Neutering prevents this, as well as perianal and prostate tumors and behavior problems. Unless
you are using a pet to responsibly breed purebred offspring tested free of genetic diseases, your pets should be spayed or neutered. This is especially important because of the high number of pets euthanized every year in the U.S. for lack of homes for them. Don’t be part of the problem, and be an advocate for responsible pet ownership.
To learn more about the benefits & risks of spaying and neutering Dogs