Why is My Black Cat’s Coat Turning Brown?

If you have a black cat, there’s a chance you may have noticed your cat’s coat change from black to a brown or reddish color. It may happen all over or just in certain spots. There are a few different things that can cause a black cat’s coat discoloration, and thankfully the most common ones aren’t cause for too much concern.

Why is My Black Cat's Coat Turning Brown?

1. Sun Exposure

You know how human hair can lighten in color if we spend to much time in the sun? The same holds true for cats. If a cat spends a lot of time outdoors or laying in sun-puddles, the color of their fur can lighten too. No big deal.

Why is My Black Cat's Coat Turning Brown? - Sunbathing Cat

2. Diet


Cats require 22 amino acids. 11 of these are essential, meaning they MUST be consumed in their diet. The other 11 are non-essential, meaning they can be synthesized and are not needed in their diet. Tyrosine is a non-essential amino acid synthesized from the essential amino acid phenylalanine. Tyrosine is also required to produce melanin, which is responsible for the pigment of your cat’s skin and coat color.

If your cat is not getting enough tyrosine, then they aren’t going to produce as much melanin. This results in a brown/reddish coat color instead of pure black. On the flip side, adding more tyrosine to a cat’s diet can reverse the discoloration, and can even turn a naturally brown cat’s coat more black.

However, according to a study done at the University of California Davis, the current amount of phenylalanine and tyrosine recommended for normal growth and health is not enough to maintain maximal melanin production for a fully black coat color. Therefore, your black cat having a brown or reddish tint to their coat does not necessarily mean that anything is out of balance in their diet. Though, this begs the question – are the current dietary recommendations for these two amino acids high enough?

Sources of tyrosine: Since tyrosine is synthesized from phenylalanine (found in proteins), feeding a diet higher in protein can help to increase production of tyrosine. Tyrosine can also be supplemented into the diet directly. Please consult with your vet before adding any supplements to your cat’s diet.


Copper is an important mineral required in a cat’s diet, involved in bone and connective tissue development, hair pigmentation, and iron absorption. Copper deficiency is extremely rare, but it can cause a discoloration in a cat’s coat color. It is also usually accompanied by other symptoms, such as anemia, ataxia, and coat texture change.

Sources of copper: Copper is found in liver and fish, though most quality cat food is adequately supplemented with copper.


Zinc is another essential mineral, important for healthy skin and coat, as well as for immunological and inflammatory processes. Consuming too much zinc, known as zinc toxicity, can cause a copper deficiency (see above). Other symptoms of zinc toxicity include lack of appetite, vomiting, diarrhea, lethargy, and more. Zinc toxicity can be fatal, so if you suspect your cat has ingested too much zinc, please see a vet right away.

Kylo Ren, black cat - Why is My Black Cat's Coat Turning Brown?

3. Illness

Another cause for a black cat’s fur to change colors is due to thyroid, kidney, or liver issues. These organs all have some type of relationship with the amino acid tyrosine (discussed above). Tyrosine is metabolized in the liver and is also necessary for the production of thyroxin, a hormone produced by the thyroid gland. If either of these organs are not functioning properly, the required amount of tyrosine is most likely not being produced, resulting in a discolored coat.

Organ issues are much more serious that the other issues discussed above, though like the copper deficiency and zinc toxicity, they are usually accompanied by several other symptoms. Please see a vet if you suspect your cat’s organs are not functioning properly.

4. Age

Age can also play a role in your black cat’s coat color. As animals age, their coats may begin to fade, or they may start turning gray. This is a normal phase of life and isn’t anything to worry about.

Why is My Black Cat's Coat Turning Brown?In most cases, a black cat having a slight brown/red discoloration or having brown/red splotches isn’t cause for concern. Chances are your kitty has just been doing a little too much sunbathing or is simply not synthesizing quite enough tyrosine to keep their coat looking purely black. However, it is important to check with your vet to be sure that there isn’t a more serious underlying issue.

Sources and Further Reading:
The Journal of Nutrition – Red Hair in Black Cats is Reversed by Addition of Tyrosine to the Diet
The ASPCA – Cat Nutrition Tips
Spot the Difference – Using the Domestic Cat as a Model for the Nutritional Management of Captive Cheetahs
PetEducation.com – Copper Requirements in Cats
PetMD – Zinc Poisoning in Cats

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By Emily