Bully cats: the worrying trend bred to resemble American XL bully dogs

Pedigree cat breeding has always attracted controversy, but an emerging fashion for cats bred to resemble American XL bully dogs may be among the most troubling trends so far.

Known as ‘bully cats’, these animals first appeared in the US and are produced through mutant breeding.

Where pedigree breeding aims to maintain purebred animals, mutant breeding deliberately combines genetic mutations to give cats a chosen appearance. In this instance, breeders combine the gene behind sphynx cats’ hairlessness with that responsible for munchkin cats’ short legs. Bully cats are therefore a munchkin-sphynx cross.

Their appearance closely mirrors that of bully dogs, a collection of breeds known for their muscular build, broad bodies and short coats. American XL bully dogs were banned in the UK in 2023.

Bully cats have recently arrived in the UK, with social-media accounts now appearing to promote the new mutant breed.

Health and welfare concerns for bully cats

Marjan van Hagen and Jeffrey de Gier, specialists in animal welfare and reproduction at Utrecht University in the Netherlands, say these mutations may have major health effects and restrict cats’ ability to move freely. Kittens already struggle to regulate their body temperature, and hairlessness makes this harder still, leaving them more vulnerable to respiratory infections.

Hairless cats may also experience sunburn and skin cancer because they lack fur. As with sphynx cats, bully cats are also without whiskers, which cats use to communicate, find their way around their surroundings and judge distances and spaces.

Cats with short legs face further difficulties. Reduced leg length restricts jumping ability, may leave cats at a disadvantage during fights and can result in painful medical conditions. Breeders maintain that bully cats are healthy and live long lives, but it remains too soon to judge their long-term health and welfare.

Some breeders also state that they screen breeding cats for conditions including heart disease. While such checks may reduce certain health risks, they cannot resolve every health and welfare concern created by mutant breeding.

A May 2024 study led by veterinary epidemiologist Kendy Tzu-Yun Teng examined annual life expectancy among UK cats. It found that the typical cat lives for nearly 12 years, whereas sphynx cats have the briefest lifespan - just 6.7 years. As bully cats are both hairless and short-legged, they could encounter twice as many challenges as sphynx and munchkin breeds.

Why bully cats look like bully dogs

In nature, unrelated species exposed to similar environmental pressures can develop comparable characteristics through a process called “convergent evolution”. Although their evolutionary histories differ, such species come to look and behave alike.

Australia’s sugar glider is one example. It resembles and behaves similarly to the US flying squirrel, despite one being a marsupial and the other a mammal. Each faced the challenge of moving effectively through a forest canopy and developed the same answer.

Likewise, numerous domesticated animals have shared features collectively described as “domestication syndrome”, including greater tameness, juvenile behaviour, floppy ears and smaller teeth. These were traits that enabled them to adapt to living alongside people.

The similarity between bully cats and dogs, however, did not emerge through this slow natural process. It is instead the product of selective breeding driven by appearance.

Veterinarian and animal welfare scientist Wenche Farstad described this in their 2018 paper on ethical breeding as breeding for “curiosity or cuteness”. Although people generally regard features such as large round eyes and short noses as especially cute, selecting for hairlessness and shorter legs fits more closely with breeding for curiosity.

Here, the likeness between bully cats and dogs is chiefly a matter of human-led design that puts looks first. Bully cats appear to have been purposely bred to resemble bully dogs, possibly because young men may view the dogs as a type of status symbol.

Could bully cats survive without humans?

Mutations that reduce an animal’s chances of surviving and reproducing generally become uncommon in the natural world. People can circumvent natural selection, however, by deciding which animals reproduce, allowing characteristics that would be harmful in the wild to continue.

There are examples throughout domesticated species. Belgian Blue cattle, for instance, need caesarean sections in more than 90% of births because their calves are so muscular.

The modern broiler chicken is another farmed animal that has been selected to grow far more quickly than its wild relatives. Many would fail to survive if they lived beyond their normal slaughter age. Without humans to look after them, bully cats would probably find survival in the wild equally difficult.

Crossbreeding schemes can raise genetic diversity and lessen damaging traits in many breeds. Yet this is not a practical answer for mutant breeds such as the bully cat, for which hairlessness and short legs are defining characteristics.

People considering a pet should understand the risks involved in owning mutant and experimental breeds. Buyers have purchasing power: declining to buy breeds with extreme traits can discourage breeders from placing appearance above animals’ health and welfare.

A shift towards ethical breeding could mean that future cats are healthier, happier and able to enjoy natural feline behaviours such as climbing, jumping and basking in the sun. We should let cats be cats.

Grace Carroll, Lecturer in Animal Behaviour and Welfare, School of Psychology, Queen’s University Belfast

This article is republished from The Conversation under a Creative Commons licence. Read the original article.