The Pros and Cons of Inbreeding in Cats

How can you tell if a breed or line is becoming too closely inbred? One sign is that of reduced fertility in either males or females. Male Cheetahs are known to have a low fertility rate. Failure to conceive, small litter sizes and high kitten mortality on a regular basis indicates that the cats may be becoming too closely related. The loss of a large proportion of cats to one disease (e.g. enteritis) indicates that the cats are losing/have lost immune system diversity. If 50% of individuals in a breeding program die of a simple infection, there is cause for concern.

Highly inbred cats also display abnormalities on a regular basis as "bad" genes become more widespread. These abnormalities can be simple undesirable characteristics such as misaligned jaws (poor bite) or more serious deformities. Sometimes a fault can be traced to a single stud or queen which should be removed from the breeding program even if it does exhibit exceptional type. If its previous progeny are already breeding it's tempting to think "Pandora's Box is already open and the damage done so I'll turn a blind eye". Ignoring the fault and continuing to breed from the cat will cause the faulty genes to become even more widespread in the breed, causing problems later on if its descendants are bred together.One breed which was almost lost because of inbreeding is the American Bobtail. Inexperienced breeders tried to produce a Colorpoint bobtailed cat with white boots and white blaze and which bred true for type and color, but only succeeded in producing unhealthy inbred cats with poor temperaments. A later breeder had to outcross the small fine-boned cats she took on, at the same time abandoning the rules governing color and pattern, in order to reproduce the large, robust cats required by the standard and get the breed on a sound genetic footing.

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