The animal loving Love Story star has written a letter to family friend, Senator Tom Udall, on behalf of People for the Ethical Treatment of Animals (PETA), asking him to support her on her mission.
Senator Udall recently pushed for U.S. horse racing reforms, and now MacGraw wants him to go further and safeguard America's horses when they come off the track.
In the letter, obtained by WENN, MacGraw urges him to throw his weight behind the American Horse Slaughter Prevention Act of 2011, which is currently before Congress.
She writes, ""It would effectively end the use of U.S. horses for food. Please, Tom, will you sign on to this bill right away, vigorously support it, and persuade others in positions of power to do the same? Time is of the essence. This extremely important bill cannot be allowed to fall through the cracks.
""The previous ban on domestic horse slaughter, which is no longer in effect, was inadequate. It simply forced sensitive American horses, including thousands of casually discarded racehorses, to endure being trucked thousands of miles in all kinds of weather, fearful and thirsty, to the Mexican and Canadian borders, only to be slaughtered in those countries.""