Freak Cat: 'Genetically Impossible' Male Calico Barred From Cat Fanciers' Association Show

Wearing a stationmaster's cap, a 9-year-old female tortoiseshell cat named Tama sits on a ticket gate at a train station in Japan on May 22, 2008. Dawntreader Texas Calboy, a calico cat from Waxahachie, Texas, has made the Cat Fanciers’ Association rewrite its rulebook. TORU YAMANAKA/AFP/Getty Images

A beautiful male cat, so genetically rare that he has been barred from competing in cat shows under certain classifications, has made the Cat Fanciers' Association (CFA) rewrite its rulebook after appearing in a show in Houston in January.

Dawntreader Texas Calboy, a male calico cat from Waxahachie, Texas, is what is known as a chimera among geneticists—his orange-and-white fur makes him look like a female. As such, judges at the Texas show said Calboy was beautiful and might even make best in show...if he were a girl cat.

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NBC reported that a male with the cat's colorings is deemed genetically deficient by the Cat Fanciers' Association (CFA). As far as the 100-year-old pet-judging body is concerned, chimerism, a genetic defect, could be detrimental to the breed. Because of this, cats like Calboy should not be competing in the best of breed category, the association says.

"It's technically almost genetically impossible to get that type of combination," Dr. Brittney Barton, at HEAL Veterinary Hospital in Dallas said, referring to Calboy's rare genetic mix.

"We don't gene test everybody, and we don't gene test all the cats, but certainly a calico male is a very rare incident," Barton added. "Especially a fertile calico male."

Calboy's owner Mistelle Stevenson explained how the cat's appearance in Houston had led to a rule change for all male cats with female fur patterns.

"[The CFA] had added him onto their board meeting in February as an emergency addendum, specifically for addressing him being shown in the ring," Stevenson said.

"They adjusted their rules to be all encompassing for all boys dressed in girls colors, not to be shown," she added.

It isn't all bad news for Calboy, however. He can still compete in the household pet and agility categories at Cat Fanciers' Association shows. He has also been accepted by the International Cat Association, winning the triple grand championship at one of its events in Denver.

"In a perfect world, I would just like for them to just look at him as the cat, and does he meet our standard or doesn't he meet it, and this is the coat color, and it happened naturally on him, it's not his fault he was born a boy and not a girl," Stevenson said.