Feature Archive 4 - Last quarter 2000
Manx rats have been available overseas in the US,UK & Europe for some time now.(Although in England the NFRS forbids their breeding, and in Sweden the authorities forbid it.)
In the last year or so Australians have bred their first Manx rats, arising from spontaneous mutations in a number of different breeding lines. Even more recently, Manx have appeared in New Zealand, having come through the lines exported there from Australia.
While this is a very exciting time for the fanciers who've found these little surprises in their litters, the general knowledge of Manx and the issues involved with breeding them, is largely misunderstood or unknown by most people here. This would undoubtedly be the result of us not having had this breed in the past.
Manx rats come in a range of 'types'. Rumpy, Rumpy riser, Stumpy, shorties & tailed. Here in Australia ANRA recognise the Manx as a standardised breed, Rumpy's are the only ones able to be exhibited While it's the norm, to breed with the other types.
Rumpy Manx have complete absence of all tail vertebrae, some even have an indentation where the tail would normally start. Rumpies have a slightly shorter body than normal tailed rats and a rounder body shape(Pic A4.1). This is natures way of compensating for the lack of tail. Most rumpy Manx rats exhibit a different gait to normal, almost a bunny hop fashion. All the rumpy Manx I know personally have no problems with balance. In fact they're more active than regular rats, climbing around like little monkeys.
Rumpy Riser Manx also have complete absence of all tail vertebrae, but these have the normal body shape. This makes the back half of their body, end in a pointed shape and sometimes an upturned look. Because of having a normal body shape, they are generally considered to be safe to breed from.
Stumpy Manx have between 1 & 6 tail vertebrae. This is usually straight, but can sometimes be kinked or even curled in a bobtail like fashion. Stumpy's are usually the Manx type of choice for breeding.
Shorties are like Stumpy's only they have more than 6 tail vertebrae, but not as many as a normal tailed rat. These are not as popular among fanciers, and don't occur as often as the other types. It would seem that these could be harder to re-home due to the fact that some of them do look like they've had an accident to acquire their shorter than normal tail(Pic A4.4). This type can be the result of stumpy to tailed Manx matings and are not used in breeding as much as the former two types.
Tailed manx are normal tailed rats that are carrying the manx gene. They usually look normal(Pic A4.5). Though on some occasions they can appear to have a slightly shorter tail than normal in relation to their body length.
Some rats can be Manx's through accidents(non-genetic manx). Mum may have been overzealous in cleaning her newborn and eaten some or all of the tail. Or another rat may have grabbed and bitten some of it off. It's tail may have gotten caught somewhere and broken off, or there could even be the issue of disease to cause it, in the example of ring-tail. There is also a nutritional condition that causes siblings to mutilate themselves and each other, and the tail appears to be one of the first places they start.
NOTE:- there is one other way a rat can become a manx. 'Docking'. While this practice is largely frowned upon by most fanciers,(including myself), it is practiced by some breeders. Said to improve the salability of the babies, tails are docked when the pups are under a week old. There can be problems associated with this practice, one of which is the mothers not accepting their 'mutilated' babies back into the nest, and in turn harming or killing them.
There is also the issue of the animal itself, having either balance, walking or movement problems due to it's unnatural lack of tail.
I personally feel that docking is a very cruel act. Not just in Rats, but in any animal. Having been a vet nurse for years, I've often had to assist the surgeon with tail docking procedures done on dogs(puppies) before. I now refuse to assist in such procedures, and have also been involved in organisations here, to ban the unnecessary and cruel habit of taildocking among dogs. There are now some canine clubs here that will accept dogs of certain breeds (ie. Doberman, Cocker spaniel, Rottweiler) in their natural tailed state.
As with the genes causing manx traits in other animals (ie cats & mice) There can be lethal outcomes to breeding manx rats.
In Cats the gene causing manx is the dominant gene M. Homozygotes (MM) die inutero. called a prenatal lethal. All manx cats are heterozygotes (Mm). Manx cats are affected by a number of anomalies of the lower vertebrae and anal region. This leads to some of them displaying a stiff-legged of stilted gait because of pelvic defects.
In the US they have longhaired manx cats they have named "Cymric"
There is another type of cat with an irregular tail. These are the Japanese bobtail cats. These far Eastern Cats are affected by a gene which causes tail shortening very different from the standard manx cats. The tail is never absent, only shorter and sometimes kinked or curled. There are no overt signs of any abnormality with this variety.
We personally breed manx mice, and while we are fortunate that the problems that can arise, never have in our lines, we still take great care with selection of breeding pairs. It would appear though, from having talked to breeders of manx rats overseas, that maybe rats seem to be more affected or susceptible to general manx related problems, than say mice are.
There are two known genes causing manx among our fancy rats. One is a dominant gene, the other a recessive one. So far the genes mutating here appear to be recessive. The combinations of genes causing taillessness in Rats are a complicated issue, there is a lot of polygenic factors to consider.(also called modifiers) These factors are sometimes not even fully understood by dedicated fanciers who have bred them for a long time. What we do know is that the shortening of the spinal cord(effecting the absence the coccygeal vertebrae of the tail) can go too far sometimes, leading to the rat exhibiting such conditions as spina bifida (S.B.)
Other documented conditions include birthing problems in rumpy manx females, due to skeletal deformity of the mother, which can lead to the death of the pups, the mother or both. The problems can range from things like the birth canal being too narrow, thus making birth impossible, through to the pelvis itself being too loosely connected to the spinal column, thus the pressure of labour can damage this area, leaving the female paralysed.
There have even been rare cases of pups born to manx parents that have absence of some joints and bones altogether, resulting in paralysis issues, and loss of voluntary bowel and urinary function.
While manx rats do have the risk of being born with deformities or S.B not all manx develop these problems, in fact they are definitely in the minority. There are breeders that have bred generations of tailless rats for years, that have never had S.B. occur in their lines. It's all a matter of responsibility.
If you're really serious about breeding manx, you must be willing to take the time to research the breed thoroughly and breed to strict rules, governing which animals are selected to strengthen the line and reduce the risk of problems.
The percentages of S.B. occurring in manx rats is in fact lower than that of some other lethalities occurring in other varieties of fancy rats. (Megacolon being just one example).
There are some other issues that have been brought up with this breed. One of them has to do with bodily temperature regulation. Because rats like so many furred animals, don't have the ability to perspire like we humans do, they lose excess body heat via their tail, ears and paw pads. This begs the question, that if they don't have a tail, then their body heat escape routes are greatly minimised.
Only fairly recently however this theory has been under question, with breeders who are living in hot climates, who breed manx, not noticing any such problems. Maybe the temp. regulating problems are also a polygenic factor, affecting some lines but not all.
Because of the lethal problems associated with the genes of this breed, inbreeding, and linebreeding are not recommended. Outcrossing is the sensible and humane way of breeding manx.
The general rule is 'never breed from a rumpy female'. If you want to have a rumpy parent, then breed a rumpy male to a 'safe' female.
If you are prepared to have your rumpy manx females x-rayed, and the results show that the skeletal form is normal in structure and size - Particularly her hips, pelvis and birth canal, then it is probably safe to breed from her. The Stumpies, shorties and tailed female manx rats are the ones used for breeding, and in some cases rumpy risers.
Because the possible complications with this breed, can be so severe, and the results being quite shocking, Manx is a controversial breed. Opinions among fanciers vary, from open acceptance to complete non-acceptance.
There are people out there doing the wrong thing, breeding for financial gain or to be the first one with something new to sell, along with other unacceptable reasons. While we as responsible fanciers cannot control these bad breeders, what we can do is control our own breeding practices & ethics, so that our lines of these more exotic breeds of rat, will be sound and well bred. By doing this we decrease the likelihood of problems occurring in our own rats and to a degree in their future offspring to other breeders.
In conclusion - Manx is only a recent mutation in Australia and it's future here is largely unknown as yet. While there is plenty of interest in Manx rats here, the general knowledge of manx health, is poor at best. This coupled with the Australian public's view of rats in general, (which needs a serious overhaul) means that for breeders like myself, there is definite cause for concern with abuse issues, should they fall into the wrong hands.
For these reasons, I am in two minds about whether to go ahead or not, in undertaking development of a healthy line of Manx rats. The thought that later on down the track, someone may be indiscriminately breeding from stock originally from my line, is a large weight to bear and one I'm not sure I want to be responsible for. Only time will tell.
I consider myself lucky to be among the small group of fanciers in Australia, to have had manx spontaneously mutate in a line of bareback rats we have.
Imagine my surprise upon discovering the little guy "Maverick", and my relief at realising 'he' was a male, rather than a female, which up until then, had been the result of all the other Manx's occurring in litters to other fanciers.
Below I've included a couple of pages from Maverick's family photo album.
'Maverick' at 3 days old.
'Maverick at 9 days old.
'Maverick' at 4 months
Even thought I am still in two minds as to whether to breed manx rats or not, I'm always trying to learn more about them, and I'd love to chat to anyone who either breeds manx rats or is interested in them.
Yours in Rodents