I have been looking for a companion for Miss Dottie since her terrier buddy died last November. Recently, I was offered a really nice tri-colored male who had to leave the show ring as his once black back and other markings are turning brunette.
Now Miss Dottie is very definitely black across the majority of her body and so was Piper when he was younger. According to the breeder, he had already won some classes when his coat started turning definitely brunette. Nothing that they have tried has stopped the color change and the vet is at a loss as to why this happened.
Piper is definitely much smaller than Miss Dottie who is around 24 pounds now and very long-backed. Piper almost looks like a mini next to her. I just met Piper this weekend and don't have any photos to show you. He is going in for all his shots and a little snip-snipping before he comes home with us. Since I don't have any plans to show him, the coat color doesn't bother me. I am just curious as to whether anyone else had heard of this before.
This is different. His entire back coat is now a warm brown, a color that some brunettes would pay to get. And his head is a lighter tan.
Color change is common in most, if not all, breeds of dog. The degree of color change varies; some noticeably so, some barely. Think of it like human hair -- most people's hair changes color throughout their life; most people get white/grey hair when they get older, but some "unlucky" few get them when they're considerably young. The same can be said for dogs, their fur can change color at any given time. Sometimes fur color changes with diet, but in that case I would think the health/texture of the fur would noticeably change whether it be for the better or for the worse.
The individual strands of fur or hair is not really grown as a color, but rather a pigment within what is really a transparent fiber. For example, white hair isn't really white, it's actually transparent -- and when it's among darker color hair it stands out as being white. I should also mention that black hair (or in this case, fur) is rarely TRUE black, in most cases it's a really dark brown that appears to be black. If the strands of hair/fur were to thin out, diet were to change, or simply genetics change causing the hair/fur to "lighten", then black hair/fur would now appear to be brown or brunette.
FYI -- a lot of dogs who normally have black whiskers change to white when they age. In addition, a dog's snout often turns white/grey as they get older too.
I had a tri, edward, he lived to be 16! He was born black and white and when he died, he was more of a tan and white and had lost a lot of his saddle. He came from a great line of show corgi's. Who knows! Just a natural course.