Cats are digitigrades3. The cat stands and walks on its digits, or toes. Digitigrades include cats, dogs, and most other mammals. Digitigrade animals generally move more quickly and more silently than other animals1.The forepaw and the hind paw both have five phalanges, of which four are functional (and carry weight) and one vestigial3 (definition of vestigial: once an important evolutionary structure, now without use2). Phalanges correspond to our fingers9.Each phalange is made up of three parts: the distal, middle and proximal phalanxes. In the front paws the vestigial phalange forms the dewclaw (first digit4). In the rear the vestigial digit is very small, is hardly apparent and there is no claw.
The metatarsals correspond to the bones in the palm of our hand9. Polydactylism (see photo to right), cat paws with extra toes, is a well known condition that can affect any cats but Maine Coons have a predisposition to the condition. It is not a health concern (see Bigfoot and American Polydactyl Cat). The maximum number of extra digits is 7 toes (see Polydactyl Cat Record Holders). The back paws only have extra toes when the front paws have them. Polydactylism is caused by a dominant genetic mutation, it appears3.
On the front paws the cat has five claws. On the hind paws there are four. They are perhaps erroneously sometimes called “retractile” because a cat’s claws are sheathed when at rest. They should, therefore be called, “protractile” meaning: capable of being protracted or thrust out; extensible5. A cat’s claws are retracted at rest to aid mobility.
Claws are curved, pointed appendages at the end of the digit and that evolve from the skin as human nails do. They are primarily made of keratin. Keratin is a fibrous structural protein that is it is tough and insoluble6. Beneath the keratin is the quick, which is pink and contains blood vessels, nerves and germinal cells. Nails grow continuously. A claw is attached to its associated phalange.
Claws are controlled by a ligament that connects the middle and distal phalanxes3. Perhaps a more accurate description is that they are controlled by the flexor and extensor tendons that connect to the base of the distal phalanx, the bone to which the claw is attached (see pictures below). The tendons that operate the claw do so by causing the distal phalanx to extend. When the flexor tendon is fully contracted the tendons lock the final two phalanges (the distal and middle phalanges) together, holding the joint rigidly3, with the claw protracted.
The flexor tendon is pulled taught by the digital flexor muscles in the cat’s legs9. Claws are used to catch (grab) and hold prey, for climbing and grip when running (a cheetah’s claws do not retract), to scrape the ground as territorial markers and to defend themselves. Cats also use there claws to knead their mothers nipple to encourage production of colostrum (mother’s milk).
Cat Paws and Claws – Original picture top left by Sister72 (Flickr) and picture bottom right by Marcin Wichary (Flickr)
Cat Paws – The above picture (believed to be in the public domain) shows a more detailed view of a cat’s digit and claw.
Cats have scent glands on the underside of their front paws, which are used to scent mark territory7.There are 7 pads on the front paws made up of five digital pads, one central pad (plantar) that takes most of the wieght and a small wrist pad. Cat paws of the hind legs have five pads, four are digital and there is one plantar pad10.
Declawing (onychectomy) is the removal of the distal phalanx. Tenectomy (or tendonectomy) is the cutting of the flexor tendon so that the claw is permanently extended8 (in the picture immediately above this tendon is called the “deep digital flexor” and “superficial digital flexor” the two together making up this tendon).
Cats claws need trimming regularly after this operation as the cat cannot carry out the normal sharpening process8. These are considered abusive operations by many people and the practice is highly controversial. It is almost always unnecessary in terms of treating a cat’s health.