by Michelle
(Pennsylvania)
My dog Toby started off very dark. His dad was a blue brindle according to the breeder. At 1, he is now grayer in color.
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Hi Janice here from Miracle Shih Tzu
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Thank you, Michelle, for sharing your sweet Shih Tzu with us. He does, indeed appear to be grayer as he gets older.
You didn't mention what color his mother is, but I don't see the blue in Toby. That is not unusual because blue is a very rare color and the mother would need to carry the gene for blue. I do see the brindling in his coat, but it doesn't show up well in the photographs.
I won't bore you with coat genetics, but the other possibility as to why the coat is graying is due to a specific graying gene, that is found on the G locus. My understanding is that it only takes the G gene from either parent to cause the coat to gray over time.