The Pros and Cons of Inbreeding in Cats

Another animal suffering from the effects of inbreeding is the Giant Panda. As with the Cheetah, this has led to poor fertility among Pandas and high infant mortality rates. As Panda populations become more isolated from one another (due to humans blocking the routes which Pandas once used to move from one area to another), Pandas have greater difficulty in finding a mate with a different mix of genes and breed less successfully.

It is almost inevitable that the Giant Panda will become extinct even if cloning techniques become available since the gene pool is now probably too impoverished for the species' long term viability. It may, therefore, be considered that all purebred animals will ultimately become unviable through inbreeding and that breeders must work carefully to maintain type while slowing down the detrimental effects of selective breeding.

Natural isolation and inbreeding have given rise to domestic cat breeds such as the Manx which developed on an island so that the gene for taillessness became widespread despite the problems associated with it. Apart from the odd cat jumping ship on the Isle of Man, there was little outcrossing and the effect of inbreeding is reflected in smaller-than-average litter sizes (geneticists believe that more Manx kittens than previously thought are reabsorbed due to genetic abnormality), stillbirths and spinal abnormalities which diligent breeders have worked so hard to eliminate.

As mentioned, some feral colonies become highly inbred due to being isolated from other cats (e.g. on a remote farm) or because other potential mates in the area have been neutered, removing them from the gene pool. Most cat workers dealing with ferals have encountered some of the effects of inbreeding. Within such colonies there may be a higher than average occurrence of certain traits. Some are not serious e.g. a predominance of calico pattern cats. Other inherited traits which can be found in greater than average numbers in inbred colonies include polydactyly (the most extreme case reported so far being an American cat with 9 toes on each foot), dwarfism (although dwarf female cats can have problems when try to deliver kittens due to the kittens' head size), other structural deformities or a predisposition to certain inheritable conditions.

The ultimate result of continued inbreeding is terminal lack of vigor and probable extinction as the gene pool contracts, fertility decreases, abnormalities increase and mortality rates rise. On the other hand, too much outcrossing will cause loss of type and therefore the loss of a distinct breed.

Selective Breeding

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