Male calico cats aren’t just rare - Dr. Marty Becker


Male calico cats aren’t just rare

Monday, Jan 20th, 2020 | By Dr. Marty Becker

Calico Cat

Male calico cats are rare, but that’s not their whole story. Here’s what I told a reader.

Q: I’ve just adopted a rare male calico cat, and I’m thinking of breeding him. Is that a good idea?

A: I hate to burst your bubble, but although male calicos are rare, trying to breed one will be a bust.

Approximately 1 out of every 3,000 calico cats is male, according to a study at the University of Missouri’s College of Veterinary Medicine, but they are generally sterile. According to feline genetics expert Leslie A. Lyons, Ph.D., that’s because calico or tortoiseshell males may have abnormalities in the X and Y (sex) chromosomes that lead to fertility problems.

Calico is a color pattern, not a breed. The orange, black and white coloration is governed by genetics. Any cat, male or female, can be orange, but in males the color is nearly always expressed in the tabby, or striped, pattern.

The gene that determines how the color orange displays in cats is found on the X chromosome. Female cats have two X chromosomes, while males have one X and one Y chromosome. For a cat to be a calico, the animal must have two X chromosomes, which means a calico kitty is going to be female the vast majority of the time.

When the calico pattern exists in a male, it’s because the cat has the unusual circumstance of three sex chromosomes: two X, one Y (male). If both X chromosomes carry the calico blueprint, you’re looking at one rare cat: a male calico. These unusual XXY animals, typically the result of faulty cell division, are called Klinefelter males, after the doctor who first described the condition.

If you have a male calico and think you can make money breeding him, you’re probably going to be disappointed because of his likely sterility. Enjoy him for the rarity that he is.

There’s more in Pet Connection, the weekly nationally syndicated pet feature I co-write with Kim Campbell Thornton and my daughter, trainer Mikkel Becker.