PATELLA LUXATION

The Russian breed is known as being a healthy breed with no known inheritable diseases.
Unfortunately, even this breed is under pressure because uneducated people just want to breed 'nice litters', not ever having studied a pedigree, without ever having had a mentor and without any knowledge of genetics.
This results in diseases in specific lines from specific catteries in the Netherlands. The use of unknown lines, non-interest of the breeder, lack of health tests of the parents and the use of low quality cats are major contributors to this development.

Everyone who breeds from an ethical point of view, knows that not all is predictable. Like in humans, lots diseases and anomalies are so rare, that not all diseases have been charted already. 
Genetics are complicated and many times things only come to light by 'trial and error'.
 

 

This also was the case with a stud that I have bred, Mithrim Celeborn.
His story I have told before and many times, but for educational purposes I will tell it again.
In my cattery I use especially English bred cats and their offspring. This means that the parents of ancestors are bred by English breeders and were imported amongst other countries, to the Netherlands. The pedigrees of these cats are known for more than 10 generations back. In one of my ex-queens is also Australian blood to be found, but that also is to be traced back to the UK catteries. 
Anyway, lots is known and lots is registered.

One of my queens was ready for her first litter and at that time I contacted a UK breeder who then owned a stud (in fact the brother to said queen) that I'd bred. I gave her two options of English bred studs that were available to me and she advised me to choice a particular stud. The inbreedingpercentage would rise in this combination, but would stay within the boundaries the GCCF holds. I wasn't aware of any illnesses or diseases within the bloodlines of both cats, otherwise I wouldn't have chosen this combination. That's why I was willing to take a calculated risk.

The combination resulted in the C litter. Four kittens, two males, two females. The owner of the father of the C litter was interested in a male kitten to continue the line and she chose and bought Celeborn. The other brother and one sister were sold als pets and Celeborns' sister, Celebrindal, stayed with me.

About Celeborns' carreer as a stud I haven't heard much, accept from other people, who said he got a lot of females to mate and that he also fathered a lot of litters within a short period of time. Because of the fact that Celeborn was a spraying male (just like his dad and granddad on mothers' side), the then owner would like to get him off of her hands. So I sold him back and had him chemically castrated within days, as he was no use to me as a stud. 
His eldest litters were about 6 months at that time and before Celeborn came back to me the then owner had contacted me with the message that a kitten had 'something wrong with the knees'. Eventually, it was obvious to me that something was seriously wrong and I told her that I needed to look at the pedigrees of the queens he had mated to perhaps find out what was the matter.
It took the mediation of yet another breeder to get her to email me all pedigrees of the queens he'd mated and that had resulted in litters.
I then took Celeborn's pedigree and the pedigrees of the females and started investigating. In the email she had said in which litters affected kittens were born, so that were the pedigrees I started to look over.
It had to be common ancestors of a common ancestor in both parents and alas, I did find one.
So, to me there was proof that Celeborn combined with specific females with the same ancestor, resulted in kittens suffering form patella luxation.

There were also litters that weren't affected at all. These were the combinations with queens who didn't share any common ancestor with Celeborn. This too confirmed, there had to be a genetic inheritable factor.

One litter with a singleton male kitten was affected too. There was no common ancestor, but this cattery uses a queen from a cattery known for so many diseases and illnesses in the cats, including proven patella luxation in her Nebelungs, that I certainly wasn't surprised to learn that this kitten had a mild form of patella luxation.
I do hope this queen will be bred with some restraint and intense study of the pedigree of the stud, as she too is carrier of the patella luxation gene, just like Celeborn.
None of my cats is suffering from patella luxation, nor their offspring.

I certainly was stupefied after the messages of the former owner of Celeborn that she, being a stud owner, had asked for all the pedigrees of the queens he had mated and let Celeborn mate his nieces, knowing his inbreedingpercentage was already high. I honestly asked myself what use it was to ask for the pedigrees of the queens, if nothing was to be done with the information and everything and anything was accepted for a mating. No breeding policy, no vision.
And off course, the owners of the queens, the breeders, too had a responsibility to check out if the stud was suitable. In many cases I have thought that those kind of breeders must have thought: "Look, a nice new stud, let's use him!" And so it was done, apparantly without any inbreedingpercentage calculations of without simply comparing the pedigrees. Unbelievable.

Anyway, the pedigrees I did compare and I have noted which names were common in both cats and so I kept coming back to 1 specific line. If you have any interest to learn the affected line, just send me an email. 
Till four generations back (so what's on the pedigree) I traced the earliest ancestor. Subsequently, I forwarded all pedigrees to a friend of mine, ms A.A. Font Freide, MSc and she has traced back the common ancestor for yet another three generations. So, the faulty gene must have had it's origin 7 generations back.
This common ancestor was in both Celeborn as the queens he mated and which had the affected litters. In this case the result is rather peculiar, as patella luxation is a disease which is said to be coupled to different (multiple) genes and not on just one. And even then it is not certain if both affected genes come together in a kitten.
But in this specific case we can say with a probability bordering on certainty, that this is the conclusion we must draw.
This was the most devastating outcome for all born kittens affected with patella luxation and their new owners. Needless to say Celeborn was neutered definitely.

Celebrindal though is not sterilised and I am planning to breed her. Why? Firstly as she is a beautiful Russian female. Secondly, as now we know Celeborn was a definite carrier of the faulty gene, the chance that Celebrindal is carrier, has dropped to 12,5% and thirdly, I am not going to combine her with studs with the same common ancestors. My own new stud Babushkablue Batman is unrelated to my queens.

For a simple overview of genetics the following scheme:
 

 XFree  CarrierSufferer 
Free  100% free50% free
50% carrier 
100% carrier 
Carrier 50% free
50% carrier 
25% free
50% carrier
25% sufferer 
50% carrier
50% sufferer 
Sufferer100% carrier 50% carrier
50% sufferer 
100% sufferer 

The scheme above is way too simple to use for illnesses and diseases with a polygenetic character (this means that more genes are affected), but in case of Celeborn and the related queens he mated this suits just right.

About patella luxation the following might be added (thanks to ms A. Font Freide):

"The patella luxation is a congenital abnormality that inherits polygenetic. There might be other causes, like being overweight, wrong movement or an accident. It isn't clear yet which hereditary components play a role in the inheritance of patella luxation. Clear is that is is hereditary (I. Eplattenier 2002-I). 
A small association has been found between patella luxation and hip displasya in the cat (I. Eplattenier and Montavon 2002 - II, McLaughlin 2002). There are also opinions heard that patella luxation in cats isn't hereditary. Duzgun (2005) didn't find the hereditary patella luxation in offspring of sufferers from patella luxation".

Complex, also because of the fact that at this moment there is only a possibility of clinically have the cat tested for patella luxation. This physical examination will tell if the cat has patella luxation in any degree or not. Cats with degree 2 and up should be excluded from breeding. And still, this says nothing about the (degree of) inheritance of the disease. There still is no dna test available, mostly because of the fact that it's a polygenetic disease.

I do hope that I have given you some insight about patella luxation. Because of this history in which one of the cats I've bred played a major part, a continuous discussion has started in and outside the social media. This discussion deflects from where it should be all about, namely preventing and eradicating patella luxation within the Russian Blue and the Nebelung. Alas, not the enhancement of the breed prevales, but earning money and in some cases even making a certain yearly profit over the backs of innocent kittens and their new owners.

Cattery Mithrim
info@catterymithrim.nl