What Is Cat “Rust”? Causes & What to Look Out For (Vet-Verified Info)

Black cats have long been associated with bad luck, but their luck has changed significantly in the last few decades. With the rise of social media cat groups, more and more people come together to discuss their love of “voids”, so named for their dark coloration and tendency to look like a cat-shaped void in pictures.

No matter how dark your black cat is, you have likely seen your cat napping in a nice sunbeam and noticed a reddish brown coloration on your cat. Is your cat becoming bleached or changing colors with age? If you’ve noticed this color shift in your black cat, then you’ve seen cat “rust”. It’s relatively common for black cats to develop “rusting”, but you may only be able to spot it when your cat is in direct sunlight. Come with us as we discuss this interesting phenomenon!

What Is Cat Rust?

Cat rust is given this name because of its tendency to appear as a rust brown color, making it look like your seemingly black cat has rusted.

In some instances, you may not be seeing rust. If your cat’s coat is a lighter shade of black or more of a dark grey, then it’s possible that your cat has a pattern to their coat that is not immediately evident but that becomes visible in certain lighting.

What Causes Cat Rust?

There are two main causes of cat rust.

Sun Exposure

The pigment that is required to produce black fur is known as eumelanin. This pigment is considered somewhat fragile, and this fragility means that the loss of the pigment often results in the coat turning to a rust color. This risk is much higher in cats that frequently spend time in the sun. Excessive exposure to the sunlight isn’t going to result in your cat’s coat rusting. It’s also associated with certain cancers in cats, such as squamous cell carcinoma.

Tyrosine Deficiency

A less common cause of rusting in cats is a tyrosine deficiency. Tyrosine is crucial for the production of eumelanin, the pigment responsible for black fur. Cats can produce tyrosine by converting phenylalanine, an essential amino acid obtained through their diet. However, if their diet is deficient in both tyrosine and phenylalanine, eumelanin production may decrease, causing black fur to take on a reddish-brown hue. Tyrosine and phenylalanine requirements can vary among individual cats, therefore, if you notice this change, it is important to consult a veterinarian to evaluate your cat’s diet and make any necessary adjustments. It is not recommended to give your cat any tyrosine supplements without your vet’s supervision.

Though a change in fur color might be perceived as non-threatening, it’s fairly obvious that the other signs of a tyrosine or phenylalanine deficiency are considerably serious. Therefore, your cat should be looked over by a veterinarian if you see any of the signs mentioned above.

Conclusion

It’s somewhat common for black cats to develop rusting of their black coat. Cats tend to spend a lot of time in the sun, often napping in sunbeams throughout the day. If your cat is turning rusty, it's usually attributed to excessive sun exposure or a nutritional deficiency.

If your cat is developing noticeable rusting of their coat in conjunction with notable signs of a medical condition, like an abnormal gait, hyperactivity, and weight loss, then your cat needs to be seen by a vet to get them diagnosed and treated quickly.

• See Also: What Is a Primordial Pouch? Surprising Facts About Your Cat's Saggy Belly

Featured Image Credit: Gavin Allanwood, Unsplash