The Manx cat is said to have originated on the Isle of Man, a part of the British Isles. It is traditionally tailless, although many of the breed do possess short tails or even full tails. The manx characteristic is due to a gene that causes deformities of the spine, and as such the mortality rate of manx kittens is relatively high.

Origins of the Manx:

There are many myths extant relating to the origin of the manx cat. Myths range from the story of the cat losing her tail when it caught in the door of Noah’s ark, to that of Phoenician ships bringing the breed from Japan, or that the cats were the offspring of hares and cats – the stories are many and varied.

Since the manx appears in many sizes, shapes, colours and fur lengths, it seems probable that various cats brought by ships to the island bred, and that a mutation or deformity present in the population gradually became more common, due in part to the isolated nature of the population.

The manx cat ranks as one of the oldest cat breeds. Tailless cats can be found in Scandinavia, and it has been suggested that one population was fed from the other, however, the question of “which came first” has not been answered.

Characteristics of the breed:

There are several categories of tail: the tailless (rumpy), a slight rise such as the tail of a bobcat (riser), a short tail (stumpy), a tail slightly off the full length (longy) or a full tail.

The manx cat has peculiarly long back legs, giving it an unusual posture with a raised rump. It has fairly rounded cheeks, giving it an appearance similar to the British shorthair. They have a double coat of fur, outward turned ears, and a fairly stocky build – the neck is short and thick, and the flanks fairly chunky. The long haired manx is known as a Cymric (pronounced Koomric), and retains the double coat of fur.

This breed is fairly active, and enjoys heights. They are intelligent, and tend to be territorial, “one-family” cats. They can be aggressive, and while they are good with children, the kittens do need to grow up with children. The older manx cat who is suddenly introduced to children may not adapt very well. The manx is often called “the man’s cat” due to its dog like characteristics – they can be trained to walk on a leash, fetch, and play other games more often associated with dogs.

Manx genetics:

The tailless characteristic of the manx breed is due to an incompletely dominant allele, which causes spinal deformities. The dominant nature of the allele provides the other reason for the spread of the characteristic through the cats on the isle. A cat that possesses the allele will have some measure of taillessness, from complete tail absence to a longish stump. A kitten of manx parents that does not possess the allele will have a full tail, and may still be called a manx, though it does not possess the essential “manx gene”.

The gene that determines the tail length is, like all genes, made up of two alleles, one from each parent. A parent can either be tailless (or stumpy) with a dominant manx allele (M) and a recessive normal allele (m), or tailed, with two recessive normal alleles. Any embryo that had inherited two tailless genes (MM) would die in vivo. “Punnet squares” showing probability distributions of manx breeding are shown below.

“Tailless” refers to any of the stumpy, rumpy, riser, longy – any of the cats that lacks the full tail. Parents are shown in bold, offspring in italics.

Tailless (Mm) to tailless (Mm) breeding:

*    M    m 

M MM Mm

m Mm mm

Offspring = Mm (tailless variety), or mm (tailed variety), in a probable ratio 2:1. Probable incidence of homozygous tailless (MM) 1 in 4. These are reabsorbed and do not reach birth.

Tailless (Mm) to tailed (mm) breeding:

*     M     m

m Mm mm

m Mm mm

Offspring = Mm (tailless variety), or mm (tailed variety) in a probable 1:1 ratio. No homozygous MM abortions will occur.

Manx cats in general will have smaller litters than normal cats, due to the absorption or stillbirth of any kittens that are homozygous for the tailless gene (MM). Tailless to tailed breeding will on average produce slightly larger litters than tailless to tailless, as all offspring in the former should be carried to term.

Deformities in manx cats:

The diagrams above would seem to indicate that breeding a tailless manx with a tailed cat will prevent deformities. Unfortunately, this is not so. The variable dominance of the manx allele means that a certain portion of the live born kittens will possess spinal deformities, and, in severe cases, other skeletal abnormalities. Deformities and health problems can include fused or missing vertebrae, spina bifida, spina bifida occulta, bowel problems, bladder problems, difficulty walking, or a hopping gait.

The stumpy, rumpy, riser and longy cats all share the manx gene – the Mm combination. The length of tail depends on the level of dominance of the manx allele. The rumpy will have a more dominant allele than the others. Hence – breeding rumpy to rumpy is likely to cause more deformities in the kittens, especially after a few generations. Breeders must carefully monitor breeding, and usually ensure that a tailed or longy is bred in at intervals, to add some less dominant alleles back into the equation. Some breeders hold that two rumpies must never be bred together, because of the risk of deformity.

It is difficult to find data on the likelihood of deformity in manx cats – as those who carry out studies are often breeders, and do want to put a positive spin on the subject. An Australian breeder’s website stated that the risk of congenital problems occurring “may be as low as 5%” in all the kittens born at a well managed breeder. I hate to think how high it could be.

Deformities and problems in the manx generally show up by about four months of age, and many breeders will not sell kittens until then. Kittens with health problems are in general either euthanased or sent to cat shelters. The nature of the problems (complete lack of bowel control is common) mean that these kittens will probably never be placed in homes.

Objections to the manx as a registered breed:

There is some controversy over whether in fact the manx is a true breed. Opponents claim that as the manx cannot invariably breed true (a manx to manx breeding will not produce all manx offspring) that it should not be registered as a breed. Breeders (conveniently) define a manx as any cat with a manx parent – thus even tailed manx, which do not possess the tailless gene, are considered “manx”. I find this argument slightly specious, but then, I’m not a breeder.

Another objection to the manx as a registered breed is the high number of deformities present in the species. Many people feel that it is cruelty to deliberately breed for a deformity, especially given the risks of kittens being deformed to such a level that their quality of life is drastically reduced, or such that they have to be euthanased.

It is very possible that only the Manx’ long standing as a breed is what keeps it in its position as a registered breed. It would certainly be very difficult to register a deformity as a true breed today.

Personal opinion:

Well, it doesn’t matter much what my opinion is – I doubt that the manx will ever be de-registered. The breed is too old and too well established. However, I do feel it is cruel to perpetuate the breed, given the high number of deformities that result. If you want an unusual cat, do the cat world a favour and get a Bengal instead.


The show requirements and characteristics for the Manx and Cymric cats can be found at
http://www.acfacat.com/breeds/standards/manxstd.html
http://www.acfacat.com/breeds/standards/cymricstd.html

Acknowlegements:
http://www.moggies.co.uk/breeds/manx.html
http://www.cat-paradise.com/cat-breeds/manx.htm
http://www4.tpgi.com.au/bywater/genetics.htm
http://www.fanciers.com/breed-faqs/manx-faq.html

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