Scottish Fold

Osteochondrodysplasia

Discussion Point

Is it ethically acceptable to knowingly breed an animal that will result in an inevitable crippling and progressive deformity?
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History

All cats with this disorder can be traced back to Susie, a barn cat in Scotland that had folded ears due to a natural mutation. She was found in 1961, and her owl-like appearance was desirable. With help from a geneticist her offspring were bred with many other cat breeds, propagating this disorder in 1966. In 1971 it was discovered that the folded ears was due to the presence of a crippling disease, and was promptly excluded from showing or breed acceptance in Europe. The United States still accepts this breed and it continues to be bred throughout the world, without any regard for the welfare of the cats.

Disease

The crippling disorder that causes folded ears in these cats is called osteochondrodysplasia. This disease is characterized by bone and cartilage malformation. Chondroplast proliferation is unstable, so proper mineralization in bones and cartilage is affected. The first sign is the ear folding, which is a direct result of weak cartilage formation; so weak that ears aren't resilient enough to resist the pull of gravity and fold over. It also results in an inflexible tail, arthritis, and crippling due to improper bone growth and improper cartilage formation, particularly in growth plates. Bone deformities progress and cause joint stress due to the poor cartilage formation. Cats typically have abnormal gait due to joint pain and inability to support weight, sometimes showing reluctance to move. This is a progressive disease with no cure, only surgical and radiation procedures to reduce pain. Folded ears become present around three weeks of age, and more severe symptoms of the disease can be seen as early as seven weeks of age.
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Current Problem

The issue with this disease is that people voluntarily propagate it due to a high demand and good profits, overlooking the animal welfare. Researchers and veterinarians insist that cats with folded ears should never be used for mating, but the public continues to buy them so breeders continue to breed them.

Genetics

Osteochondrodysplasia is an autosomal dominant trait. It also shows incomplete dominance in heterozygotes, which causes varying degrees of the disease compared to the severity of the disease in homozygotes. All cats carrying the dominant allele have folded ears, indicating the presence of disease, and cats without have straight ears, which are disease free. The genotypes are homozygous dominant (Fd/Fd), heterozygous (Fd/fd), or homozygous recessive (fd/fd).

~Mating two homozygous individuals will result in 100% folded ears

~Mating a homozygous and heterozygous individual will result in 100% folded ears

~Mating two heterozygous individuals will result in 25% homozygous dominant, 50% heterozygous, and 25% homozygous recessive. 75% of litter will have folded ears.


Testing for osteochondrodysplasia is unnecessary because the folded ears is a clear indication of its presence. Testing and X-rays only come in handy to determine the severity of the crippling as the cat ages.

Eradication of Disease

To be rid of the disease, all one would have to do is exclude folded ear cats from breeding programs. This can be done in one generation. Unfortunately, only a handful of breed clubs internationally exclude scottish folds in order to decrease their breeding; International Feline Federation and Governing council of Cat Fancy in Europe. The demand is still high since they are still accepted as a breed in many other areas of the world, and are especially popular in the Unites States. One precaution that breeders are taking is avoiding homozygous folded ears, which results in severe crippling. They are instead aiming to breed only heterozygotes, which still develop the disease, but possibly to a lesser extent.

Conclusion

Breeding this painful disorder in cats is unethical. Owners who allowed their cats to be used in the study done at Istanbul University said that they bought the cats because of their folded ears, a unique trait among cats. Few knew that the folded ear was due to a disease, and soon found out that their beloved cat was succumbing to the progressive painful disorder. All studies done on this disease by veterinarians and researchers seem to agree on one main concensus: that it is unethical to breed this disorder into cats. It decreases the cats quality of life by causing pain in movement, and cannot be treated. Breed clubs need to exclude Scottish Folds from their accepted breeds in hopes to reduce demand. Breeders should stop breeding them altogether. Breeding two unaffected scottish shorthairs will yield the same desired temperament without the abnormality. Ideally, outlawing the breeding of this abnormality due to the poor welfare state of the animals would be the best solution, but we are far off from that. Not enough is being done to control the spread of this disease, and it is only becoming more popular.

References

Aydin D., K.A Hunatmaz, D.O. Erdikmen, K. Ozer, D Durmus, and K. Avanus. 2015. Hereditary osteochondrodysplasia in scottish fold cats. Istanbul University: 1-7.


Chang J., J. Jung, S. Lee, H. Kim, O. Kweon, J. Yoon, and M. Choi. 2007. Osteochondrodysplasia in three scottish fold cats. J. Vet. Sci. 3:307-309.


Hubler M., M. Volkert, B. Kaser-Hotz, and S. Arnold. 2004. Palliative irradiation of scottish fold osteochondrodysplasia. Vet. Rad. Ult. 45:582-585.


Malik R., G.S. Allan, C.R. Howlett, D.E. Thompson, G. James, C. Mowhiter, and K. Kendall. 1999. Osteochondrodysplasia in scottish fold cats. Aust. Vet. J. 77:85-92.


Takanosu M., T. Takanosu, H. Suzuki, and K. Suzuki. 2008. Incomplete dominant osteochondrodysplasia in heterozygous scottish fold cats. J. Sm. Anim. Sci. 49:197-199.