By Judith Schulz, Prairiebaby cattery, Canada.
(Please note: This article can be applied to other breeds as well!)
When a breeder brings new foundation lines into the Cattery for the first time, he will most likely ask himself the following questions: What type of test breedings are the most conclusive? What about inbreeding tests? When are they necessary and where do they start to become rather useless?
Even though most people believe that incest will give us clarity about recessive genes, such test periods will, in reality, only give us very vague and incomplete information. Usually new foundation cats have a genotype that is unknown to us. Unknown genotype means we don't know if they are carriers or not. Carriers for what? We dont really know what we are looking for in a new foundation cat, right? In other words, there is no way for us to calculate how many kittens would be needed to obtain conclusive results for anything. This is when inbreeding tests come into effect. Since we cannot tell the likeliness of foundation cats for certain recessives, we might have to produce many, many inbred litters to find out more about a new line. This could very well mean close to 100 kittens or even more.
What about the ethical side of long test breeding periods? If we breed full brother and sister over several generations, we automatically make the t- and b- cells in the kittens equal to some extent. Since these cells are responsible to recognize and fight disease, the general immunity of the animal would decrease accordingly. Some old time breeders of our breed have done many inbreeding tests to find out about hidden colors or to improve type. (it should be mentioned here that the better way to find out about masking factor would have been to cross the foundation cat to a Siamese cat instead of to its brother - but thats besides the point.) Produced were often chronic snifflers with sensitive tummies that had to be kept in an almost sterile environment to stay somewhat healthy. This type of breeding experiment, if done over several generations, will likely bring to life a good number of babies that stand a good chance to die of early age cancer, have terrible gums and teeth, develop all sorts of allergies and/or become chronic URI carriers All this simply because they have a weak immune system. Did you know that schizophrenic and irritable behavior can also be a side effect of inbreeding depression? It seems to be overlooked that the new owners of our "by products" will have to pay for all the medical care, in case the test breeding period did effect the immune system of the kittens. In the midst of our projects - most times with the best intentions, I agree - we tend to forget sometimes that this is not only about pedigrees and genetics. Considering that pet homes are usually the best living environment for our babies, would this be fair towards both the owner and the little creature?
Here it should also be mentioned that embryos with heavy defects often get absorbed and are not being born. Our only evidence would then be a smaller litter size. Absorbed and stillborn kittens are very common in inbred litters. Were the "invisible" absorbed kittens the ones with the pectus? Would the two stillborn kittens in our litter have developed a kink tail at 5 months of age - who knows? -- Have we not brought in the new foundation line in order to get fresh blood into the breed -- only to end up in the same pattern that we are actually trying to get away from? It should also be mentioned that some foundation cat colonies already have a certain amount of inbreeding. They really should not be inbred anymore.
If a breeder wants to find out if the foundation cat carries a certain simple recessive gene he/she could breed that cat to a known carriercat. In this case about 16 kittens would have to be produced to be about 99 % sure that the foundation cat does not carry this specific genetic fault. These kittens would NOT have to be inbred. We would then run into the problem with the affected gene pool. After our 16 kittens testing phaseis over, we will logically mix our new line with common show lines and integrate the fresh blood into the general gene pool. Since all purebred species are relatively inbred (line bred) already, many of them actually DO carry the same genetic defects. This means that the offspring of the "tested line" will be bred back into the affected gene pool and the problem will probably pop up again after two generations. Then what have we gained? Shall we perhaps go ahead and produce another 16 kittens with a known carrier at the next generation - and the next generation?
What about the "7 kitten method"? Some people say that test breedings would make more sense if one partner carries the undesirable gene homozygous. This cat then would only have to produce 7 kittens to be about 99 % sure that the other breeding partner is clear of this specific gene. Here is another question: If that cat carries the gene homozygous it would logically also display it (have the problem), right? Now if the genetic fault is severe, would we want to produce several litters with such cat just to find out if our new foundation cat carries the same gene? If on the other hand- the genetic fault is not severe and we just want to find out about an undesirable beauty fault like lockets or a kink tails, then the 7 kitten method would surely have been useful if - yes if it wasnt for all those lovely polygenes!
Another aspect is that of new mutations. A test breeding can produce several new gene mutations that would have not come up in any other breeding, even with the same breeding couple. In other words, kitten number 15 or 16 might display the bad gene we are looking for - but not because the parents carry it but because of a sudden change of cells.
Even though new foundation lines are thoroughly screened and tried out by a responsible foundation breeder, we cannot guarantee these lines to be free from genetic faults. As a matter of fact, no living being is free from genetic faults. People who like to start with "clean foundation stock" need to realize that there simply IS no clean foundation stock. All cats and all lines carry unwanted recessives. There are no clean lines and there are no perfect cats. If we would do inbreeding tests in our current show lines - followed by selection, how many cats would be left in our breeding programs? If we know the answer then why in the world would we even consider test breeding our foundation cats? It seems as if this method would be a step backwards. We would almost be trying to breed for the undesired instead of directly breeding for the DESIRED characteristics.
Here is another thought for people who still think they know their proven show lines and are only concerned about all the terrible faults a foundation cat might carry: Inbreeding tests with one parent being new foundation and the other parent a full pedigreed cat would give us no more evidence about the "cleanness" of our new line than it would give us evidence about the "cleanness" of our old line. Why? Because the recessive genes would have to be carried by both breeding partners, in order for them to be displayed in the offspring. In other words, if a problem pops up, the new line would not have brought anything undesirable into our breeding program that we don't already have.
Often breeders include one outcrossed cat into a cattery, consisting of an average of 5 to 15 or more cats with tightly bred pedigrees. This new outcross then has the task to balance out genetic defects that have manifested themselves over many years. It usually doesn't work that way. It takes time to breed away from things. We are deceiving ourselves if we think we can speed things up with inbreeding tests. If we do them anyhow, we can be almost certain that our inbreeding tests WILL bring us problems because our foundation cats do carry undesirable genes just like every other cat - no need to test breed! What do we do when we find out? Get everything spayed and neutered and start from scratch? And then if another problem arises in our next new line (which will most likely happen, and if it's only from all the inbreeding tests :-), shall we then discontinue that line also? Or do we keep the offspring for breeding and hide complications from others, just to offer them what they expect from us - "clean" foundation? Why inbreed to find out what everybody should expect regardless?
Summary: Defective recessive genes can only be eliminated to some extent, no matter if and no matter how many test breedings are being performed. This is true for ALL Maine Coon cats. Our hope is to bring in unrelated new blood lines and breed these to our common show lines. These cats can bring new problems into our old lines just as much as our old lines can give additional problems to our new foundation cats. However, problems with genetic faults can be minimized or even corrected over a few generations - as long as we stay away from inbreeding. A recessive gene can only become a problem if both parents carry the gene. The chances that two cats carry the same genes are much smaller if they are unrelated. If a problem arises, we can deal with it then and there. A combination of TOS (Testing for genetic diseases, Outcrossing and Selecting) is not the answer to all health concerns. Yet, outcrossing is definitely the most efficient way to reduce immune related problems. Outcrossing combined with testing and selecting is also to some extent an effective tool to fight problems with genetic diseases. Had we avoided to breed with a too limited gene pool from the beginning, we wouldnt have to pay for expensive HCM and HD tests today - simply because these problems would not exist to this overwhelming extent. Many of us strive for good health, but we will never fully succeed in our goals and visions. Even with the best intentions, breeding will remain a gamble and a lot of work. We continue to pray and hope for the best. Though hope can be frail it springs eternally..........