Why does a cat spend so much time grooming its fur?

The obvious answer is to keep itself clean, but there is much more to grooming than this. In addition to cleaning away dust and dirt or the remains of the last meal, the repeated licking of the fur helps to smooth it so that it acts as a more efficient insulating layer. A ruffled coat is a poor insulator, which can be a serious hazard for a cat in freezing weather. Cold is not the only problem. Cats easily overheat in summer-time and fur-grooming increases then for a special reason. Cats do not have sweat glands all over their bodies as we do, so they cannot use sweating as a rapid method of cooling. Panting helps, but it is not enough. The solution is to lick repeatedly at the fur and deposit on it as much saliva as possible. The evaporation of this saliva then acts in the same way as the evaporation of sweat on our skin.

If cats have been in sunlight they increase their grooming even more.

This is not, as might be imagined, simply because they are even hotter, but because the action of sunlight on their fur produces essential vitamin D. They acquire this crucial additive to their diet by the licking movements of their tongues over the sun-warmed fur.

Grooming also increases when cats become agitated. This is called displacement grooming and it is believed to act as an aid to relieving the strain of tense social encounters. When we are in a state of conflict we often 'scratch our heads'. A cat under similar conditions licks its fur.

Any cat-owner who has just been holding or cuddling their cat will be familiar with the animal's actions as soon as it has been released from human contact. It wanders off, sits down and then, nearly always, starts to groom itself. This is partly because it needs to smooth its ruffled fur, but there is also another reason. You have, by handling the cat, given it your scent and to some extent masked the cat's scent.

The licking of the fur redresses the balance, weakening your scent and reinforcing the cat's own odour on its body surface. Our lives are dominated by visual signals, but in the cat's world odours and fragrances are much more important, and an overdose of human scent on its fur is disturbing and has to be rapidly corrected. In addition, the licking of the fur you have been handling means that the cat can actually enjoy 'tasting' you and reading the signals it gets from the scent of your sweat glands. We may not be able to smell the odour of our hands, but a cat can.

Finally, the vigorous tugging at the fur which is so typical of a cat's self-grooming actions plays a special role in stimulating the skin glands at the base of the individual hairs. The secretions of these glands are vital to keep the fur waterproofed, and the tugging of the cat's busy tongue steps up the waterproofing as a protection against the rain.

So grooming is much more than mere cleaning. When it licks its fur a cat is protecting itself, not only from dirt and disease, but also from exposure to cold, from overheating, from vitamin deficiency, from social tension, from foreign odours and from getting drenched to the skin. No wonder it devotes so much of its waking day to this piece of behaviour.

There is one danger inherent in this activity. Moulting cats and cats with very long fur quickly accumulate a large number of hairs inside their alimentary tracts and these form into hairballs which can cause obstructions. Usually hairballs are vomited up naturally without causing any trouble, but if they grow too large they may become a serious hazard. Cats of a nervous disposition, which do a great deal of displacement grooming, also suffer in this way. To solve their problem it is necessary to find out what is causing their agitation and deal with it. For the moulting and long-haired cats the only prevention is regular grooming by the cat's owner with brush and comb, to remove the excess fur.

Self-grooming begins when the kitten is about three weeks old, but it has its fur attended to by the mother from the moment of its birth.

Being groomed by another cat is called allogrooming, in contrast with self-grooming which is known technically as autogrooming. Allogrooming is common not only between mother and kitten, but also between adult cats that have grown up together and have developed a close social bond.

Its primary function is not mutual hygiene, but rather a cementing of the friendly relation that exists between the two animals. All the same, licking in a region that is hard for the cat itself to reach does have a special appeal, and cats are partial to attention behind the ears. This is why tickling and rubbing behind the ears is such a popular form of contact between cat-owners and their cats.

The autogrooming actions often follow a set sequence, when a cat is indulging in a complete 'wash-and-brush-up'. The typical routine goes as follows: 1 Lick the lips. 2 Lick the side of one paw until it is wet. 3 Rub the wet paw over the head, including ear, eye, cheek and chin. 4 Wet the other paw in the same way. 5 Rub the wet paw over that side of the head. 6 Lick front legs and shoulders. 7 Lick flanks. 8 Lick genitals. 9 Lick hind legs. 10 Lick tail from base to tip.

If at any stage during this process an obstruction is encountered – a tangled bit of fur, for example – the licking is momentarily abandoned in favour of a localized nibble with the teeth. Then, when all is clear, the grooming sequence is resumed. Foot and claw nibbling are particularly common, removing dirt and improving the condition of the claws. This complicated cleaning sequence differs from that seen in many other mammals. Rats and mice, for example, use the whole of their front paws for grooming their heads, whereas the cat uses only the side of the paw and part of the forearm. Also, rodents sit up on their back legs and groom with both front feet at the same time, while the feline technique is to employ each front leg alternately, resting its body on the one not in use. Human observers rarely comment on such differences, remarking simply that an animal is busy cleaning itself.

In reality, closer observation reveals that each species follows a characteristic and complex sequence of actions.