@Roberta,
A few years ago, maybe on this thread, I started to go on and on about a great photo of Secretariat as an older horse, you know me and photography madness, but I couldn't find the photo online to prove it was Secretariat. I wrote the secretariat website and got a nicely worded letter back that I was quite wrong, with a true photo of him. He didn't grey as he aged, remained red.
The horse I was thinking about turned out to be Carry Back (however you spell that) as an all or near all white horse. Snort, wrong again.
Ahhhhhh,
http://www.secretariat.com/