Manx Genetics and FAQ's
Please note here that anything that refers to "Manx" also applies equally to "Cymric" as Cymric are longhaired Manx. It will help to read the genetics overview first.
Overview of Genetic Inheritance
What do you expect from Manx to Manx matings?
What do you expect from Manx to Tailed matings?
What are the risks?
How does the Breeder manage risk?
You may be interested in reading the following article, which is a summary outlining the background of scientific research (with references) that provides us with our understanding of the Manx gene, how it is inherited, and what it does. You can return to this page anytime using the menu at the left:
"Research History of Manx Cats"
An Overview of Genetic Inheritance (Glossary)
Geneticists are learning more about inheritance every day. However, we do have a pretty good idea about many of the factors in cats that breeders work with. To understand what happens with Manx at a genetic level we do need to get a basic understanding of some of the terms used.
For every gene, the kitten-to-be inherits one allele from each parent. The combination of the two alleles is called a gene.
Where the alleles inherited are different, the embryo is described as being heterozygous for that gene. Where the inherited alleles are the same, the embryo is said to be homozygous for that gene.
In the heterozygote, the alleles are usually a dominant allele (represented by an uppercase letter), and a recessive allele (represented by a lowercase letter). For example, with many coat-colour genes, the dominant allele determines what the cat looks like. But it is not always this simple.
A gene may exhibit variable expressivity. This means you see a greater or lesser effect depending on how much it express itself.
Finally, a gene can be pleiotropic. This means it has multiple effects, not just one as we often assume.
That should be enough to go on with.
"Can you mate Manx cats to Manx cats?"
Yes. There are two types of matings that can be made in a Manx breeding program:
Tailless to tailed where "tailed" means a normal-tailed offspring from Manx parents, called a Tailed Manx
A tailless cat – Cymric or Manx – has the genetic combination (Mm) and a normal-tailed cat has the geetic combination (mm). Whichever of the two types of matings is carried out, the resulting litter may include tailless kittens (Mm) or normal-tailed kittens (mm). The diagrams in the next sections illustrate how the alleles are mixed-and-matched to determine the expected average result.
What do you expect from Manx to Manx Matings?
In this diagram it can be seen how two tailless Manx parents are expected to produce TWO tailless Manx kittens (Mm) for every ONE tailed kitten (mm), on average. To work this out, the alleles of the parents are set out at the top and side of the grid (grey squares); usually the male parent is at the top. The main grid then contains the recombined alleles from the corresponding tops and sides, which represents all the possible combinations that might be concieved (yellow squares).
|
| |||
|
tailless Manx X tailless Manx |
Tailless Male |
||
|
M |
m |
||
|
Tailless Female |
M |
|
Mm Tailless |
|
m |
Mm Tailless |
mm Tailed |
|
|
|
|||
The (MM) configuration is crossed out because it is believed to produce a non-viable embryo that fails to develop and is reabsorbed by the Mother during pregnancy. This is the reason we see a 2:1 ratio of tailless kittens from these matings (on average, of course). This effect is homozygous lethal, due to the failure of the homozygote (MM) embryo to develop.
Of course, in the case of the Manx, there is no way to know if any particular mating has actually produced a MM embryo, as it may happen that none of the embryos concieved inherit the tailless allele (M) from either parent in any given mating. Likewise, it is possible that all embryos inherit the (M) from both parents, and, being then homozygotes (MM) all are absorbed. The only way we can "see" this occurring is to look at the numbers over many matings. Over many matings the numbers will indicate that on average there will be tailless to tailed kittens born in a ratio approximating 2:1.
This also suggests that, given that the domestic cat has an average of 4 kittens in a litter, litters from a tailless Manx to tailless Manx mating should average 3 kittens, another statistic that is borne out over many matings.
As demonstrated in my own breeding program, over the course of several breeding seasons, tailless Manx to tailless Manx matings produced anything from 1 to 7 kittens (averaging 3.5 kittens). It was observed that two thirds of these were tailless or partially tailed all of the genotype (Mm) and one third were born with normal tails, genotype (mm). This is precisely what the research suggests should be expected from these matings.
What do you expect from Manx to Tailed Matings?
In this diagram it can be seen how a tailless Manx cat mated to a tailed cat are expected to produce TWO tailless Manx kittens (Mm) for every TWO tailed kittens (mm); that is, a 1:1 ratio of tailless Manx to Tailed, on average, over time. In this type of mating (recall that "tailed" may be a British or European Shorthair, or a tailed offspring from a Manx mating), the MM configuration does not occur.
|
| |||
|
tailless Manx to Tailed |
Tailed |
||
|
m |
m |
||
|
Tailless |
M |
Mm Tailless |
Mm Tailless |
|
m |
mm Tailed |
mm Tailed |
|
|
|
|||
From this it can be seen that all possible conceptions are viable. This suggests that, given that the domestic cat has an average of 4 kittens in a litter, litters from tailless Manx to Tailed matings should average 4 kittens over time.
Demonstrated in my own breeding program, over the course of several breeding seasons, tailless Manx to Tailed matings produced anything from 1 to 7 kittens (averaging 4.2 kittens). It was observed that half of these were tailless (Mm) and half were born with normal tails (mm). This is precisely what the research suggests should be expected from these matings.
Regardless of the type of mating, however, it must be said that any single litter may be comprised of entirely tailless Manx or entirely tailed or a mixture of both. Mostly a mix is born, but I have seen a tailless to tailless mating produce 7 normal-tailed kittens, and I have seen a tailless -tailed mating produce 6 tailless kittens.
This should not be a surprise at all. Probability dictates that every embryo concieved has an equal chance to inherit any of the combinations listed for that mating. So whether you get all of one thing or one of everything, so to speak, it really the result of the genetic lottery.
What are Rumpies and Stumpies?
The Manx allele, as stated in the genetics overview above, exhibits what is called variable expression. This is the best explanation for the variable tail lengths we see in tailless Manx cats. This means that all kittens inheriting the Manx allele are tailless but the degree of taillessness can vary due to the variable expressivity of the Manx allele.
So, depending on how much the Manx allele expresses itself, tail lengths vary from no tail at all (Rumpy) to a little bit of tail (Stumpy) or a rather long stump tail (Longy).
Kittens that are born with perfectly normal tails in Manx litters do occur and have the genetic configuration (mm) like any other cat. They do not have the Manx allele and so their tails are not affected. They are called "Tailed Manx".
Why are normal-tailed kittens from Manx litters called "Tailed Manx"?
Kittens that are born with perfectly normal tails in Manx litters do occur and have the genetic configuration (mm) like any other cat. They do not have the Manx allele and so their tails are not affected. So, genetically speaking they are not "Manx" cats.
Most people associate the term Manx Cat as being a cat with no tail. Some people think that stumpies are not Manx either because they have some tail. So, how should the term Manx Cat be defined for the purposes of breeding?
Breeders define the term "Manx" as being any kitten born that has a Manx parent, regardless of the tail length of the kitten. That means that any kitten will fall under the categories of Rumpy Manx, Stumpy Manx, Longy Manx or Tailed Manx.
That is as it should be and allows for breed integrity - breeding partners can be chosen from entirely within the breed. So, mating Tailed Manx (mm) to Tailed Manx (mm) will produce a litter of Tailed Manx (mm). Mating a Rumpy, Stumpy or Longy Manx (Mm) to a Tailed Manx will produce kittens that are either Rumpy, Stumpy, Longy or Tailed Manx.
Do Manx cats "Breed True"? Are they a true "breed"?
Genetically speaking, Manx cats do not "breed-true".
This is a genetic term for a genotype that reproduces itself every time, so if Manx could "breed-true" then they should be able to produce viable Manx cats homozygous for the Manx allele (MM), and all their offspring would be (MM) Manx. But as we have shown above, this doesn't happen.
Because any embryo that inherits the (MM) configuration is not viable, the living Manx kittens are heterozygous for the Manx allele (Mm). Genetically speaking, this is a hybrid and means that regardless of the type of mating, any Manx mating will produce normal-tailed kittens, as described above, that do not inherit the Manx allele at all (mm).
Anti-Manx advocates use this argument to influence registering bodies against the breed. Because of this "evidence of hybridisation", there are a few Australian registrars that will not accept Manx as a breed in its own right, only according it sub-register or experimental-register status, and Tailed Manx kittens get no registration at all under such a system as they are not deemed to be "Manx".
However, I would argue that this is an unfair attitude toward a breed that can only produce heterozygotes, or hybrids, for a specific gene without even crossing them outside of the breed! Poor form indeed!
Instead, a registrar should look whether Manx are a "true breed". They should examine whether breed integrity can be maintained when assessing Manx as a breed in its own right . That is, can one breed Manx without outcrossing to other breeds? The answer to this is a utter and resounding YES!
A "Manx" is much more than just the sum of its tailbones! Being Manx also means a particular head and body type, coat quality and eye colour, and most importantly, "Manx" ancestry. Tailed cats from Manx litters (Tailed Manx) exhibit all the important body type characteristics, except for taillessness. This makes them the perfect tailed "outcross" to use in a Manx breeding programme.
Some registrars allow for outcrossing to British Shorthair to maintain type, introduce new colours, or introduce a normal-tailed cat to break up generations of tailless-tailess matings. But, to maintain breed integrity, breeding partners must be chosen from entirely within the breed. In the case of Manx, a Tailed Manx should be preferred over British, as long as all other points of type conform to the standard.
Therefore, a Tailless Manx to Tailed Manx Mating can (and should) be defined as a"Manx to Manx" mating. Under these conditions, Manx breed integrity can be maintained, and all the tail types have the natural right to the name "Manx", whether they be no-tailed, partially-tailed or normal-tailed, by virtue of having Manx ancestry.
From this point of view, Manx can be considered a "True Breed" and there is absolutely no good reason for any registrar not to fully recognise the Manx as a breed of integrity in its own right. All tail types should be registered in their own categories up to and including full register with championship status (take note, CFA of NSW, and all other anti-Manx rotters!)
Does mating Manx to Manx cause deformities?
No. This question usually assumes the mating of tailless to tailless, like rumpy to rumpy. But It is not the tailless to tailless mating that causes deformities. Though that should not be taken to mean that there is no risk of congenital deformity.
Given that the Manx allele can be passed on in either a tailless/tailless or a tailless/tailed mating it is not so much the type of mating that is the problem. The risk is more a function of the relative expression of the Manx allele - the greater the expression, the greater the risk.
That puts rumpies at a greater risk than stumpies, for example, regardless of whether one or both parents were tailless. So, given that rumpies are at a higher risk, it is wise not to do rumpy to rumpy matings over successive generations as that appears to compound the risk in subsequent generations. This is why a good Manx breeding programme controls this risk by including all tail types, periodically introducing a Tailed Manx to break up generations of tailless-tailless matings.
This is also why breeders (both registered and backyarders) should know what they are doing. So be careful when buying kittens, because many do not understand what the hell they are working with and how best to control the risk factors.
Is there such a thing as "Manx Syndrome"?
No. In Veterinary medicine there is NO condition that is officially given the name of "Manx Syndrome". There can be NO Manx 'syndrome' for the following very good reasons:
This term seems to have been adopted by a few people to try to categorise, under a single heading, a number of conditions that may occur in Manx cats. Please be aware that this is a recently coined layman's term that seems to arise out of people's desire to give names to things they don't understand. It really has no place in the vocabulary of the Manx breeder, owner OR Veterinarian, and if your vet uses this term, I'd consider changing vets if I were you.
There are a lot of fallacies floating around the ether about Manx Cats. I will even go so far as to say that there are vets who, when confronted with a Manx, are quick to blame anything irregular on the maligned Manx 'gene', and perhaps even call it "Manx Syndrome", whether or not the condition could be traced back to the Manx gene as a probable cause. This only serves to spread paranoia about this breed and Manx breeders would like to see the use of the term stopped.
What are the risks?
Before we get into this topic we need to establish that risks are not certainties. A risk is a statisical inference (usually expressed as a percentage) that gives some idea of what might happen in a given circumstance. Saying something is at risk of disaster does not mean that disaster is a certainty to occur unless the risk is very, very high.
The Manx allele is pleiotropic. This means it has multiple effects. The principal effects are:
All spinal vertebrae are on average 1mm shorter than normal - this gives the Manx it's characteristic slightly-shorter-than-usual back
Fewer spinal vertebrae, which usually means fewer caudal vertebrae (tailbones) but can also mean fewer lumbar or sacral vertebrae if the cat's back is too short
Fusion of caudal vertebrae (tailbones), including kinks and twists in stumpies and longies
A gradual curvature from front to back, enhancing the Manx's rounded look
Because we are dealing with a gene that has a deleterious affect on the spine (of which the tail is an extension), there are attendant risks and it would be foolish to deny it. How greatly the Manx allele expresses itself is something the breeder has limited control over.
So, what is the risk that we are talking about here? The risk is that the Manx allele may have a detrimental effect on the health of a kitten that inherits it. It may, perhaps, affect the important sacral or lumbar regions of the spine (the lower back region) or the nerves associated with it. This can give rise to problems toileting, walking or, if the formation of the bones is incomplete, spina bifida.
Over all the kittens born in a season under a well-managed Manx breeding program, the risk of congenital problems occurring (that may be attributed to the Manx allele) may be as small as 5%. That is to say, 95% of Manx kittens would have no problems.
It may be said that the more the Manx allele expresses itself, the more the spine may be affected and the higher the risks could be. This puts Rumpies at the highest risk, Stumpies and Longies are at low risk. Tailed Manx, not having the Manx allele at all are at no risk and this is why these are included in a good breeding programme.
Even the incidence of spina bifida can be controlled to a large degree. It works on a genetic threshold, so matings between two cats with a high genetic threshold for spina bifida, even though they don't have it themselves, increases the risk of the kittens being born with it. Breeders can control this risk by not repeating any matings that produce spina bifida kittens.
How does the Breeder manage risk?
The best plan for managing the Manx cattery is to have a mixture of Rumpy, Stumpy and Tailed Manx types in the breeding program (perhaps also to employ the occasional breed-outcross to British- or European-Shorthair in countries where this is permitted). That is, to mate higher-risk cats to low-risk or no-risk cats.
Rumpies can be mated to Rumpies quite successfully. But there is some concern for possible accumulation of risk by mating high-risk cats together over successive generations. Therefore, it is common practise for the offspring of such a mating to be mated to a Stumpy or Tailed cat, reducing the risks to the offspring of the following generation.
Even the incidence of spina bifida can be controlled to a large degree. It works on a genetic threshold, so matings between two cats with a high genetic threshold for spina bifida, even though they don't have it themselves, increases the risk of the kittens being born with it. Breeders can control this risk by not repeating any matings that produce spina bifida kittens.
In these ways the likelihood of congenital deformity is minimised. This seems to work quite effectively at reducing the overall risk in the program, in so far as the breeder has control.
How can I tell if My cat is a 'real' Manx or just a moggy?
How can you tell if a Manx is a pedigree or a moggy?
These questions are linked, I believe. Generally the person who asks these questions has a tailless cat or kitten at home and wants to know if their cat is the real thing. Some might say it is a matter of opinion. There are several points which have a bearing on the question:
Firstly, a registered Manx must have a recorded family tree, called a pedigree.
Secondly, a Manx cat must have at least one Manx parent.
Thirdly, a cat can be equally Manx whether it has a pedigree or not.
A better question might be; "What differentiates a show-quality Manx from an ordinary one?" because having a pedigree is not the way to tell. In all breeds of animal there are very ordinary specimens that are not good enough for a show bench because they don't meet their standard. I have also seen unregistered Manx that fit the standard perfectly, but aren't showable because they aren't registered and don't have a pedigree. So a show-quality Manx must have two things... A registration paper, and the correct head/body/tail type that fits the required standard. After that, it is a judge's decision.
Is your pet a 'real' Manx? if it was born with no tail or a stump-tail, and at least one of its parents also had no tail or a stump tail, then very likely it is. Lack of registration papers doesn't make it any 'less' Manx than one which does.
What should I feed my Manx Kitten?
A cat is a carnivore. I should note at this point that those cats of mine which have hunted and eaten mice, rats & rabbits regularly have been the healthiest cats I have ever had (I will confess to the some birds, too, and I don't want any greenies e-mailing me about my cats hunting, thanks. You can take your cat-skin hats and go get a real life).
What does this tell me about cat diet? Everybody wants their cat to have a 'normal' diet. For the cat, the ideal is to be allowed to hunt. But that is not always the most practical thing to do. So what then?
For the regular diet, I have to recommend a good prepared food. In a dry food, bypass the supermarket and go straight for the good stuff sold by vets and some pet shops that is designed to be a complete diet and reduce the incidence of FUS (Feline Urological Syndrome). A 'complete' diet is one which the cat can do well on with only that and water and no supplements. Generally they have varieties tailored to meet your cat's age and activity level. In a tinned food look for a brand that sources all the protein from meat. Be careful about vegetable content. No soy or wheat protein in tinned foods, please, if it can be avoided, as I have experienced a cat allergic to foods containing vegetable proteins in tinned (wet) foods.
For Australian owners, try to get hold of some "Whiskas Advance", the single best prepared food I have ever come across to-date. No, they aren't paying me. I kept my breeding cats on this for years and they thrived on it, adults and kittens alike.
Other good prepared foods are IAMS, Eukanuba and Hills Science Diet dry varieties.
If you must have a supermarket available food, Whiskas (in the purple box) is the dry food of choice, and after that, Friskies Go-Cat dry food varieties. Both of these are complete foods, no supplements required and only the provision of fresh water besides. But FUS may still be a risk with these.
Chicken is good. Wings are the best. Give your cat chicken wings (must be raw) a couple of times a week. The bones in wings are soft and fine enough for the cat to grind away at them, eating them entirely and thereby keep the teeth and gums healthy and providing valuable calcium in its natural form. If you can get rabbit, that's great too. A cat can eat all the bones in a rabbit except the spine and rear legbones. If you know someone who goes hunting and can get you the odd whole rabbit (skin, insides and all), that is even better.
What about milk? This is not as silly a question as it sounds. I have always been particular to tell people that milk is a no-no. Many cats, not just Manx, will develop diarrhoea as a result of ingesting milk. Even the low-lactose stuff. Once a kitten is weaned, there is no longer a requirement for milk in the diet. So please; just plain, fresh water daily.
If you are in a hard water area where there is a high iron content, there may be a risk of constipation... it might pay to filter the water if this appears to be a problem.
My cats also like a piece of sliced cheese as a treat from time to time. The milk content of cheese doesn't pose a problem, I think because the rennet enzyme completely converts the lactose.
There will always be somebody who will argue with me: "I have fed my cat such and such for years and he is fine and healthy". That's OK with me. Please bear in mind that my recommendations are based on experience with more than 100 pet and breeding cats and kittens over that time, and what I found kept them healthiest. This does not detract in any way from what you find works for your cat.
Your pictures show cats with no tails! Do they have a normal spine?
These cats are meant to have no tails. They are born this way. As the tail is part of the spine, they therefore do not have a normal spine. The gene that causes the taillessness (the Manx factor) affects the whole spine to some degree, which gives the cat its characteristic "shortness of back". That the tail is all or partly missing is just the obvious effect. This does not affect the quality of life of an otherwise healthy Manx cat in any way.