Cat inbreeding causes what is described as “inbreeding depression” which is another term for general weakness. Robinson’s Genetics for Breeders and Veterinarians provides a list of signs of inbreeding depression which are as follows:
- There may be a decline in birth weight. The kittens may be small, thin or lethargic.
- The kittens may demonstrate developmental problems. There may be poor growth in later life and below standard adult individuals.
- The average litter size may be reduced. There may be an increase in the number of stillborn or abnormal kittens in litters.
- Reproductive performance may be negatively affected. The male my demonstrate a reluctance to copulate. The female may show a reluctance to come into heat. Either sex may show partial sterility.
- At any stage of development there may be a greater proneness to illness. For example, a regular appearance of cancer in younger animals. There may be a loss of immunological diversity which can cause significant losses of cats or kittens to the same disease.
- There may be physical signs such as asymmetry in the face, crooked noses, uneven eye size or alignment and misaligned jaws. Does coat pattern symmetry mean good health?
To this list I would add one more: a lack of intelligence or poor cognitive function. I have seen this in inbred British Shorthair cats. It is noticeable. The cat is dull and slow moving.
Only one of the above examples may be present. There may be a small but detectable deterioration in a number of the above symptoms. Inbreeding depression may come on gradually. It may affect some individuals and not others.
The point is this: some cats do carry deleterious genes and these deleterious genes may make their presence felt due to inbreeding.
There is an interesting story on the Internet today which is essentially about the inbreeding of Persian cats. Somebody who had purchased three Persian cats gave up on them and abandoned them. They were dumped outside an animal shelter (Woodside Animal Welfare Trust) in the UK.
The founder of the shelter, Carole Bowles, says that over the last 10 years they have had Persian cats dumped at the gate at least once a year. It would seem that local buyers are buying from the same breeder who is inbreeding her cats.
The founder of the shelter adds that on every occasion the Persian cats have had health issues which she says are commonly related to inbreeding or poor breeding. Sometimes the cats are so unwell that they have lost their fight for life. Other times they can be restored to reasonable health and adopted out. Inherent defects in inbred Persians cannot be cured such as tear duct overflow and poor breathing.
In this story of Persian cat abandonment, the cats arrived fearful and in bad health but the shelter did a very nice job and they are now less fearful and looking for attention. However, people who donate to a cat shelter should not be picking up the pieces left behind by irresponsible cat breeders who inbreed their cats while focusing on appearance. It is ironic that so often inbred Persian cats look weedy, ill, ugly and fragile. They do not look like healthy pet cats. So much for breeding for appearance.
When cat inbreeding is bad the “product” is ugly and the business is ugly too.
Here is a chart indicating in the degree of inbreeding in purebred cats:
Story source: devonlive.com.