This extract, by Andy Lawrence, is from an article entitled “THAT DOG WON’T HUNT” by Lisa Davis and published in the April 2003 issue of DISCOVER magazine.

The article of course is about dog breeding but we have the same issues in cat breeding. Ms. Davis talks about the problems breeders are having because of inbreeding and line breeding. I am sure that most of you know that inbreeding is breeding siblings or father to daughter or mother to son. Line breeding on the other hand is in fact inbreeding but further removed. To line breed we would breed to a relative but not as close a relative. The breeding to a great aunt or

problems dominant genes. On the other hand by total outcrossing we cannot produce consistent type.

Ms. Davis suggests in the article that breeders find another breed that has the type they are looking for and outcrossing to that breed, which of course is what we try to do with the domestic cat. The problem with using the domestic is that even though the phenotype (how the cat looks) might be correct, the genotype (actual genes behind the cat) is not known and thus we cannot count on type. However, if we can use a breed that has the same physical type then it is undoubtedly dominant for many of the same genes behind the breed we are working with. This would mean that we would have the benefit of those genes while

enlarging the gene pool at the same time. We would be able to come back into our own breed with hybrid vigor while maintaining type making the progeny three-quarters pure. It is Ms Davis’ belief that as breeders, by so doing with the various breeds, that in time the genetic problems could be either removed totally or at least diminished.

I would recommend that each and every one of you take the time to find this article and read it. It certainly is an eye-opener at the least. I know that we cannot engage in such breedings without approval of our parent organizations but we can talk about the possibilities of starting such programs within those organizations and possibly eventually get approval.

uncle would be considered line breeding as would breeding to a kitten or puppie’s great grandparent. The purpose of line breeding is to set dominant traits. When two animals are bred together that have no common ancestors we have no idea what the progeny will look like. If we breed siblings, the chances of genetic problems are much more likely than if we line breed, which is why most breeders choose line breeding to produce their kittens or puppies. To set a dominant trait we have to choose parents with that trait and breed them together. However, if they do not have common ancestors you will not necessarily get the desired trait. By having the common ancestors you can then set the traits you are looking for.

Now comes the problem. With line breeding you also run the risk of setting the genetic problems as dominant traits. Many breeds are faced with this issue today. Abyssinians for instance suffer a higher than normal rate of renal amyloidosis and gum disease. Persians are undergoing polycystic kidney disease (PKD) while other breeds have things like cardiomyopathy and eye problems not to mention the breeds that have birthing problems. By line breeding or even inbreeding we take the chance on making these genetic

Pussy Warmer!