Robyn Anderson of Love and Hisses has a new set of kittens. An interesting thing about this litter is that three of the four kittens are partially or completely tailless. The above picture is from her blog – isn’t he cute?
This got me to thinking about the ways cats with short or missing tails are made.
There are several breeds of ‘tailless’ cats out there, and also a few ‘bobtailed’ cats. The most well-known of the former are the Manx. The most well-known of the latter are the Japanese Bobtail. Interestingly, the two mutations that these breeds have are not related to each other.
The Manx cat mutation is from a gene called, helpfully enough, the “Manx Gene”. The gene is dominant, but not fully dominant. Like White Spotting, having two copies of the gene in a kitten has a much increased effect. In the case of the Manx gene, though, this effect is invariably lethal. In most cases the double-dose kitten dies in utero and is reabsorbed by the mother, so Manx litters are somewhat smaller.
The Manx gene shortens and distorts the spine, starting at the tail. The effect is variable, again like White Spotting, controlled by other genes like a volume knob. Modest ‘volume’ gives a short tail, more gives a short stumpy tail, even more gives a tiny knob or no tail at all. Sadly, even with one gene the ‘volume’ can sometimes be even higher and cause malformations in the spine further into the back legs, or nerve and muscle issues. These “Manx syndrome” kittens die at a very young age.
The preference for totally tailless kittens means that breeders are skating very close to producing these kind of kittens. Breeders normally use one Manx and one non Manx to avoid the stillborn babies, much like the similar issues Scottish Fold cats have. I’ve heard it said that if the Manx cats were not a historical breed, they might have had a lot of problems getting it accepted as a breed. The ‘Ojos Azules’ breed was dropped when similar fatal side effects tied to the mutation were found to be linked to the mutation.
American Bobtail Cats
This breed is a relatively new breed, supposedly a new mutation much like the Manx, discovered in this country. While the info I read was pretty cagey, from the sound of their breeder organization’s ethics rules it sounds like this mutation has problems similar to that of the Manx, if not identical to it. Like the Manx, the effect runs the gamut from no tail to fully tailed. From the sound of it, fully tailed cats are docked sometimes.
The intent of the program is to produce a lookalike to a bobcat. The breed has no bobcat genes that have been detected, and I haven’t heard that bobcat tails vary much in length. An advantage to these breeders is that the more risky tailless cats are forbidden to be used in breeding. Since they want ‘stumpies’, the chance of fatal defects in the kitten are reduced. But if you believe their ethics rules, not completely eliminated.
These cats have an entirely different mutation – the tail is short, but not missing. I think I heard at a documentary that these cats have the same number of bones in the tail, they are just short. This gene is a recessive, so both parents must contribute a bobtail gene. I haven’t heard that there are any dangers associated with this mutation.
In Manx Circles, this would be known as an “Ultra Longie”…