Neuticles

Neuticles are prosthetic testicular implants for neutered dogs and other domestic animals. The implants may be made of polypropylene or silicone.
History.
Gregg Miller developed the idea for Neuticles after his bloodhound, Buck, was castrated to stop his wandering. Miller, along with a veterinarian, patented the procedure for implanting Neuticles. To sell his idea, Miller established CTI (Canine Testicular Implant) Corporation, and the first commercial Neuticles were implanted in 1995. Miller won the 2005 Ig Nobel Prize in Medicine, a parody of the real Nobel Prize, for the invention of Neuticles.
Humans cannot legally get Neuticles. While the material is FDA approved, a second approval is required for each area of the body into which an implant is placed.
Opposition.
In the UK, the regulatory body for veterinarians, the Royal College of Veterinary Surgeons, states that the use of any form of cosmetic surgery is unethical.
The Veterinary Council of New Zealand says "the insertion of neuticles (prosthetic testicles) cannot be justified. This procedure has no benefit to the animal and can be used to conceal genetic defects."