Below is a documentary video (in five parts) about Monsanto making a request to patent pigs with a certain genetic makeup they claim is created by a proprietary breeding method only they own the rights to. If any of the pigs with a genetic marker from Monsanto were to breed with other pigs, then their marker would get into the general population and result in a similar phenomenon as their genetically modified corn germinating and spreading.
The pig patent story became so controversial, that Monsanto sold their pig patent to Newsham and got out of the pig business completely. [source: Monsanto]