Food allergy?

I've been looking at this picture a lot because I love the size difference between my massive old cat, Joey, and his new best girl, the petite Connie. Upon closer review, I noticed something I didn't like -- Joey's fur is a new color by the base of his of his tale. For more than 14 years, his coat has always been a uniform hue across his entire back.

I never noticed this when I pet him because he's very "one sided." He curls up on the same side whenever he sidles up against me for a cuddle or in the sun for a nap. But sure enough, when I checked him out, I can see that his coat is indeed thinning back there.

It might be a food allergy. Since Connie joined us, I have been giving her and allowing Joey to snack on Purina One instead of the prescription food Reynaldo must have. I thought it was an easy way to economize, since neither Joe nor Connie has Rey's dietary restrictions.

That ends today. Hopefully by the end of the month, Joey's lustrous coat will be back. If not, it's another trip to the vet. He'll hate it, of course, but it's for his own good.