Are Short-Tailed Cats' Tails Natural or Altered?

The Connection Between Short Tails and Genetics

A research team from Peking University in China embarked on a study to explore the similarities in tail shapes between Japanese Bobtail cats, known for their short tails, and domestic cats in southern China. Assuming that there should be a shared genetic factor variation between the two, they conducted a largescale genetic survey focusing on cats with varying tail lengths.

Starting with 20 shorttailed cats and 20 cats with normal tails found in southern China, the researchers investigated the "Tbox" gene variation in Manx cats, which are naturally tailless. However, they did not find any of the four mutations associated with tail deformities.

The team then bred a shorttailed female cat from southern China with a male cat of normal tail length, resulting in two litters of 11 kittens. Observations of the kittens' tails revealed three with normal tails, three with mild short tails, and five with moderate short tails. This pattern confirmed that short tails are autosomal dominant in inheritance, but with variation in tail length, indicating incomplete dominance—a phenomenon where dominant traits do not always express 100% of the time.

Following this, the researchers conducted a massive comparative survey of hundreds of cats, both with normal and short tails, and uncovered the following facts:

The Relationship Between Cat Short Tails and Genetics

The "HES7" gene on chromosome E1 is the causative gene for short tails.

When the T in "HES7" is replaced by a C, it leads to tail deformities.

A heterozygous genotype of "C/T" results in mild to moderate short tails.

A homozygous genotype of "C/C" leads to severe short tails.

Short tails are formed by three variations: reduced vertebrae, hemivertebrae, and fused vertebrae.

The "HES7" gene is not associated with body deformities beyond the tail and ribs.

"HES7" does not affect reproductive ability or survival rates.

Even without the "HES7" variation, some cats can exhibit short tails.

Cats with normal tails do not have the "HES7" variation.

Genetic mutations in "HES7" are the reason for the common occurrence of short tails in Southeast Asia and southern China.