Skeletal Variations and Problems

The cat's skeleton is one of evolution's superb achievements. In the natural cat, problems such as arthritis and decalcification are caused by disease or normonal or dietary upsets, not poor design.

Until recently, there was little skeletal variation in cat breeds: unlike the dog, which has been radically changed through selective breeding, the cat escaped extreme modification.

Environmental pressures do create natural variations. In hot climates, cats are naturally small; a small animal has a higher surface-area-to-weight ratio, which helps it to keep cool.

Free-breeding cats in cold climates, such as Scandinavia, Russia, Canada, and the northern United States, have larger, heavier skeletons.

In natural circumstances, severe skeletal anomalies disappear, most often because lethal problems or survival drawbacks are associated with them. Some, such as taillessness or extra toes (polydactyly), may be perpetuated by their occurrence in a limited gene pool.

The natural tailless breeds all developed on islands, and isolated gene pools also perpetuated the high proportion of seven-toed cats around Boston, Massachusetts, and Halifax, Nova Scotia.

Active selection for a breed standard has led to more dramatic changes recently. Siamese and Orientals today have much longer and thinner legs bones than their predecessors, while the British Shorthair's skeleton has become more compact, with heavier long bones.

This kind of active intervention has perpetuated the most considerable and worrisome skeletal problems. Exaggerated shapes increase the risk of painful inherited arthritic problems.