John, i have an old red cattle dog nearing 13 years old, like Blitzen she's certainly going grey now, but gets hidden well - more like they just fade in colour.
She still gets out & about well thanks to fish oil tablets that we put in her food now.
It's been cold ( well for us NQ folks) for a while & getting them off the ground on a good raised bed has certainly helped her!
Always a sad thing to put a good dog down!