A cat’s tail is made of bone (caudal vertebrae), ligaments, tendons, cartilage, muscle, skin and hair. A typical cat has between twenty-one and twenty-three caudal vertebrae which are extension of the spine. Exceptionally a cat with a full tail may have as few as eighteen or as many as twenty-eight of these bones. They reduce in size towards the tip and the final one is a small conical cap. The first caudal vertebrae attaches to a special backbone called “the sacrum”.
Domestic cat tails vary in length among the cat breeds although they are a very similar length among random bred cats. The tail is nearly always more than 8 inches in length and less than 12 inches with about 10 inches being the average unless the cat is tailless.
Ligaments are made up of tough elastic tissue which connect bone to bone, vertebra to vertebra.
Tendons connect muscle to bone and are made up of tough, fibrous connective tissue. They are similar to ligaments and like ligaments are made of collagen.
Articular cartilage covers the area where each individual vertebra meets the next vertebra. Normally, there is cartilage between connecting bones in a skeleton.
Skin covers the vertebrae and in the skin there are cells which produce the hair strands. Of course, there’s also muscle in the tail which is why a cat can so elegantly move their tail. This is important because the tail is not only a balancing tool but is also used to communicate. For example, the “tail up” position is a friendly greeting.
To see the cat’s tail used as a balancing tool you might look at the snow leopard which has the thickest and longest of all tails. This cat has to navigate 40° rocky escarpments when chasing blue sheep. It may hunt a blue sheep from above to blindside them but they have to navigate very dangerous slopes and the use of their tail for balance significantly helps them.
As an interesting diversion from the anatomy of the cat’s tail, the well-known Siamese cat inherently has a kinked tail. When they were first imported into England this was very noticeable but over many years of selective breeding the kink has been removed but you can still feel it. You will still see this kink in Siamese street cats in Asian, if you can see one, because in Thailand where this cat originates from, you rarely see them apparently. In 1992 it was said that in Hong Kong about one third of the cats had tailed kinks and in the more northerly Malay states this rises to two thirds.
Some purebred cats are bred without tails such as the well-known Manx and the Japanese bobtail.
Cats’ tales are very expressive and sensitive. They should not be grabbed and pulled but they can be touched delicately.