The Manx Cat - The Genetics of the Tailless Cat Breed

The Manx cat originated, as you might expect, on the Isle of Man, and at first glance may appear to be a cat like any other. But this native island breed has one particular distinction that sets them apart from the vast majority of other cat breeds and types in the world: they have no tails, or only a very short, stubby tail a couple of inches long. They are also distinctive due to their rather long hind legs, rounded heads, and the superior hunting skills that made them popular and in demand for many years as farm cats and ship’s cats. Manx cats have been known of in the wider world since at least the early 1800’s, and are now bred all over the world as well as on the Isle of Man.

So, how come Manx cats don’t have tails, and are there any health concerns associated with this unusual breed trait? Read on to find out more!

The genetics behind the signature tailless-ness

The cause of the Max cat’s lack of tail is a spontaneous genetic mutation that occurred at some stage in the distant past of the history of the breed. The gene for the tailless appearance of the breed is considered to be a dominant gene, meaning that it will often override the gene for normal tail development if a cat carrying the gene for tailless-ness mates, resulting in many of the resulting kittens also being born without a tail. The fact that the gene for tailless-ness spread so widely and is present in all of the cats of the breed and most of the cats that originated on the island is also partially due to the limited gene pool of cats that are available within a closed environment such as an island. So in time, the tailless-ness became a standard trait of the breed itself.

Different types of Manx cat tails

While a total lack of a tail is the most commonly recognisable signature trait of the breed, various other varieties of partial tails are also present within the Manx cat demographic as a whole. These different tail versions and their names are described below:

• “Rumpy” is the term used for a Manx cat with no tail at all, although there may be a tuft of fur present where the tail would usually be.
• “Riser” is the term used for a Manx cat that has a small bunch of cartilage where the tail would usually be, which is usually most clearly visible when the cat is arching their back and lifting their “tail.”
• “Stumpy” Manx cats have around an inch of tail.
• “Stubby” Manx cats have a definite but stunted tail, usually around half of the length of that of a normal cat.
• “Taily” or “Longy” Manx cats have a tail present that is greater than half the length of a normal cat’s tail, sometimes even being approximately full length.

Breeding Manx cats

The gene that causes Manx cats to be born without a tail (or with an unusual tail variant as described above) is a dominant gene, which means that if two tailless Manx cats reproduce, the resulting kittens would also be born without a tail. Cats can only carry one copy of the gene; carrying two copies of the gene is unviable for life, and results in spontaneous miscarriage of the kittens in question. For this reason, breeders will very rarely attempt to breed two tailless Manx cats, and will instead usually breed a Manx cat with some form of tail with a tailless cat in order to pass on the tailless variation safely and in a way that is viable for life. Litters produced from a mating of this type will produce a litter with all varieties of Manx tail possible; not all of the kittens that result from mating will be totally tailless.

Issues with stunted tail development

Sometimes, partial tail development in the Manx cat can lead to a painful form of arthritis of the tail and back, and Manx cats that are born with tails in the “stumpy” to “taily” length are sometimes docked (their tails are removed). This is to prevent the kinked and sometimes painful tails that come about due to abnormal tail growth at the developmental stage.

A condition known as “Manx syndrome” can occur if the gene that leads to tailless-ness also affects the spine by over-shortening it, and can lead to damage to the nerves of the spinal cord, and a form of feline spina bifida. This condition can also cause problems with the digestive system and bowels, and cause bladder problems including the bladder’s development to be stunted and smaller than normal. This condition usually leads to a dramatically shortened lifespan within affected cats, usually proving fatal at just three to four years old. The condition most commonly affects “rumpy” Manx cats, with around 30% of cats of the Manx breed estimated to suffer from this condition, the vast majority of them being “rumpy.”

Recent breeding programmes among Manx cat enthusiasts have gone a long way towards breeding this problem out of the gene pool, by ensuring that “rumpy” Manx cats are bred with “stumpy” ones, which has led towards decline in the number of cats with Manx syndrome being born year on year.