Chimpanzee Toni celebrated his 50th birthday at the Hellabrunn Zoo in Munich on Nov. 22, 2011. Sven Hoppe/DPA/Landov hide caption

itoggle caption Sven Hoppe/DPA/Landov

Michael Sharry visits with Bill, front, and Lou (now deceased) on Nov. 8, 2012, at Green Mountain College in Poultney, Vermont. Toby Talbot/AP hide caption

itoggle caption Toby Talbot/AP

After a leg injury didn't heal well earlier this year, Lou has difficulty walking. He and his partner, Bill, will be slaughtered at the end of the month, and their meat will be used to feed students at Green Mountain College in Vermont. Nina Keck/Vermont Public Radio hide caption

itoggle caption Nina Keck/Vermont Public Radio

A man holds a sign during a "Dogs Against Romney" demonstration outside the 136th Westminster Kennel Club Dog Show at New York's Madison Square Garden, on Tuesday. Shannon Stapleton /Reuters/Landov hide caption

itoggle caption Shannon Stapleton /Reuters/Landov

Breeding sows in crates at a subsidiary of Smithfield Foods in 2010. The photo was shot by the Humane Society as part of an undercover investigation. Humane Society/Associated Press hide caption

itoggle caption Humane Society/Associated Press

A chimpanzee eats a coconut at the Alamogordo Primate Facility at Holloman Air Force Base, N.M., in an undated photo from the National Institutes of Health. A plan to move chimps that had retired to the facility after being subjects of medical experiments sparked controversy and a review of research policies. AP hide caption

itoggle caption AP