cats fir changing color

Question
I have a 4 year old medium long, all black domestic cat that was rescued as a kitten.  I work with a rescue group and I have been fostering her for about 2 1/2 years.  We recently bought a house.  She did pretty good with the move and adjusting to the new house.  But within less than a month her fir around her neck, face and part of the chest is turning completely silver gray.  She seems healthy but the fir continues to get lighter every day.  The vet has no clue why this is happening.  Have you ever heard of this and do you have any idea why this is happening?

Answer
Hi, Suzette.  I have a 7-year-old cat just like this.  Actually, his name is "Crazy Color" because he can't seem to decide which color he wants to be!  What I notice with him is that the fur gets black in the winter, but when he sheds his winter coat and grows in his summer coat, his mane and chest turn silver.  The rest of the fur stays black.

The reason it happens with my cat is he's half Himalayan.  If you've never seen a Himalayan, they have dark faces, tails and legs, called colorpoints.  The body is slightly lighter, but they have a very light (often almost white) ruff around their necks.  This ruff is temperature sensitive.  The warmer the skin is, the lighter the ruff.  So in the warm summer, it's common to see a very light ruff, and during the cold winter, it darkens.  Of course, being a mix, my cat's coat doesn't have colorpoints to the extent that a purebred's does, but he definitely is lighter on the chest and around the face in the summertime.  I'm thinking this is a possibility with your kitty.

Lack of protein can cause black fur to change color, but it generally turns a rust color, not silver.