As of 2013, only one method of chemical castration had FDA approval for use on dogs. Known as zinc neutering or "zeutering," this one-time process injects a chemical compound into the dog's testicles, where it kills sperm and collapses tubes inside the testicles. Chemical castration allows your dog to keep his testicles but is every bit as permanent as conventional neutering.
Once your dog has been injected with a zinc-based chemical castration solution, the effects are permanent. It takes about 30 days to take effect, but has a success rate of approximately 99 percent and renders your dog permanently sterile. While the benefits of a chemical castration do not include reversibility, it may spare your dog the physical discomfort of having his testicles surgically removed; it can cost less than conventional neutering; and it virtually eliminates the post-neuter recovery period.