Black coat color is produced by a pigment called melanin. Melanin is the same pigment in human skin that turns our skin brown(er) when we are exposed to sunshine. Melanin is found in higher concentration in black coated animals than other color coats.
Melanin is made from amino acids obtained from the diet. Amino acids are smaller chemical structures that make up the larger structure called protein. Phenylalanine and tyrosine are two important amino acids involved in melanin synthesis.
Most mammals can produce tyrosine from phenylalanine. However, cats are not as able to make the conversion as other mammals.
Therefore, if a black cat is eating a diet low in animal sourced proteins (beef, lamb, pork, fish, chicken, eggs, dairy), that cat’s coat may turn reddish. The red color almost looks like the coat is bleached from the sun. However, healthy coats do not bleach from the sun.
To treat the red coat – increase meat in the cat’s diet. This can’t be as simple as switching from a grain-based food to a meat-based food. Even better would be to start your cat on a real meat diet – either raw or very lightly cooked.
Dr. Cathy Alinovi DVM
As a practicing veterinarian, Dr. Cathy treated 80% of what walked in the door — not with expensive prescriptions — but with adequate nutrition. Now retired from private practice, her commitment to pets hasn’t waned and she looks forward to impacting many more pet parents through her books, research, speaking and consulting work. Learn more at drcathyvet.com
Holly
July 5, 2016 at 12:58 pm
Very interesting. Years ago, before I knew what should, and shouldn’t be in my pet’s food, I had a lab/golden mix whose black coat would always turn a reddish color in the summer. I thought it was normal.
Jean M. Casey
July 5, 2016 at 1:35 pm
Black coats can turn reddish with too much sunlight. Owners of pure bred show cats NEVER let their cats lie in the sun because the color of the coat can change.
Lisa P.
July 5, 2016 at 3:12 pm
It is unusual for this to be for a kitty, to have low thyroid because they tend to go hyperthyroid, but when we treated our kitty for hypothyroid, her black fur that had turned brownish, turned back to shiny black. You will have difficulty finding a Vet who understands this, however. She has Adrenal issues, as well as thyroid issues. But she is feeling much better now that we have her on the right hormone balance! And she is 16 years old.
Maxine Schmidt
July 5, 2016 at 7:24 pm
I am under the impression that this goes for dogs as well. Please correct me if I’m mistaken. I have a black Standard Poodle this was happening to a few years ago, I changed brands from from Natural Balance to Champion’s Acana and seemed to resolve the problem. Initially I thought she might be a “blue” in color, but her coat went back to black after the change. This may have been coincidence, but I thought it worthy of an opinion..
Christine
July 6, 2016 at 6:16 pm
My vet told me that my black cat’s coat turning reddish can also be attributed to his kidney disease. He eats a high protein diet but also spends a lot of time lounging in the sun in his outdoor catio.
Marie
July 7, 2016 at 1:03 pm
I’d go with what Dr. Cathy says over your vet’s take on coat color change. Dr. Cathy told me, when two of my meat-eating cats showed elevation in kidney values (specifically creatinine) that these normal kidney parameters are set for kibble eaters. In other words, if you take, say, 1000 cats eating just kibble, those cats create the range for “normal” kidney ranges. Meat eaters will almost always be above these so-called normal ranges. At least that’s my understanding of it, and my cats with some kidney elevation are definitely not in any sort of kidney distress. In fact, they’re nicely plump and active – no signs of any kidney dysfunction whatsoever.
Linda Chiolero
July 18, 2016 at 11:35 am
RI am very sorry to learn that Dr. Cathy has retired from private practice. I have some friends in central Indiana who drove 1-1.5 hours to see her for her expertise. I have followed her via Facebook and other online sites for the past couple of years. I wish her much continued success in her future endeavors.
Jim
September 5, 2018 at 1:31 pm
I had a rescued black kitten who was clearly dying of malnutrition: not growing, pretty much no body fat and severe muscle wasting, whiskers broken off, and his coat was dull, dry, and orangey-red. Other kittens raised on the exact same kitten diet had thrived. Fecal tests were negative. But one vet still thought there could be a parasite involved, and suggested trying a dose of Droncit before resorting to an expensive PCR test. Result: The kitten promptly began to thrive and today is a magnificent adult cat with a glorious shiny black coat and long luxuriant whiskers. Apparently this kind of malnutrition can be caused by a heavy parasite load, not just by diet (at least in young kittens).
Alyssa M
November 7, 2019 at 11:11 pm
My cat had bladder stones and a bladder infection we fed him a high protein diet with no grains and his fur was turning reddish (he’s medium grey) and the issue was the food, (blue buffalo) and she said there were way too many minerals that he just didn’t need! I would say it isn’t always up to one thing, we switched to a veterinarian brand and he’s happy healthy and has a wonderful coat that is back to the normal color! He’s a Russian blue we think but have not gotten tests done
ThePawzLab
May 5, 2021 at 11:32 pm
I enjoyed this piece. Want to add few more points:
1. If your black cat just loves soaking in sun then there is nothing to wonder in the fact that why a black cat’s coat turns brown.
2. The only possible reason behind a cat having a black coat is that both of its parents contain black coat genes called Allele. There are various hues in the black gene which reveal cinnamon, brown, and solid black colors. If you see some brown stripes on your cat in sunlight then it means one of its parents isn’t fully black.
3. If over time your cat’s hair is looking a lot brownish than black then it means your cat is a tabby in disguise and not fully black. It happens because the tabby gene is dominant.
Tara B
July 29, 2021 at 6:56 am
Thanks- this comment was extremely informative!!
Tom
March 15, 2022 at 3:08 pm
So is it bad for the cat if this is happening ? Her wet food is grain free. Dry food is kept out all the time. The dry food is replenished once a week if that…