Feeding

Cats are highly specialized for hunting and have evolved to survive on a meat-based diet. Since they have a greatly reduced need to digest plants, their digestive tract has evolved to be shorter, too short for effective digestion of plants but less of a weight penalty for the rapid movement required for hunting. Hunting has likewise become central to their behavior patterns, even to their predilection for short bursts of intense exercise punctuating long periods of rest.

Even well-fed domestic cats may hunt and kill birds, mice, rats, scorpions, cockroaches, grasshoppers, and other small animals in their environment. They often present such trophies to their owner. The motivation is not entirely clear, but friendly bonding behaviors are often associated with such an action. It is probable that cats in this situation expect to be praised for their symbolic contribution to the group. Some theories suggest that cats see their owners gone for long times of the day and assume they are out hunting, as they always have plenty of food available.

Ethologist Paul Leyhausen, in an extensive study of social and predatory behavior in domestic cats (documented in his book Cat Behavior), proposed a mechanism which explains this presenting behavior. In simple terms, cats adopt humans into their social group, and share excess kill with others in the group according to the local pecking order, in which humans place at or near the top. Another possibility is that presenting the kill might be a relic of a kitten feline behavior of demonstrating for its mother's approval that it has developed the necessary skill for hunting.

Due to their hunting behavior, in many countries feral cats are considered pests. Domestic cats are occasionally also required to have contained cat runs or to be kept inside entirely, as they can be hazardous to locally endangered bird species. For instance, various municipalities in Australia have enacted such legislation. In some localities, owners fit their cat with a bell in order to warn prey of its approach, however the cat may figure out how and when the bell works and learn to move more carefully to avoid ringing it.

Domesticated cats eat fairly little vegetable matter. It is quite common, however, for cats to occasionally supplement their carnivorous diets with small amounts of grass or other plant matter. Cats munch on grass, leaves, shrubs and houseplants to facilitate regurgitation of whatever may be upsetting their digestion; or perhaps to introduce fibre or trace minerals to the diet. Whereas bears and dogs commonly supplement their diet of meat with fruits, berries, roots, and honey when they can get them, cats prefer to mostly feed on meat. All felines, including the big cats, have a genetic anomaly that prevents them from tasting sweetness, which very likely is related to their meat-dominated eating habits, and almost certainly related to their aversion to fruits and berries. However, many domesticated cats are known to like vegetables. The majority of brand-name cat foods are primarily meat based, but often contain large amounts of corn or rice, supplemented with meat byproducts and minerals and vitamins.

Cats are obligate carnivores, and cannot live on an unsupplemented vegetarian diet because they cannot synthesize several required nutrients which are absent or rare in plant food. This applies mainly to taurine, vitamin A (cats cannot convert the pro-vitamin A that is abundant in plants to vitamin A proper) and to certain fatty acids. The absence of taurine causes the cat's retina to slowly degenerate, causing eye problems and (eventually) irreversible blindness, a condition called macular degeneration. Cow's milk is a poor source of taurine and adult cats are generally lactose intolerant. Lactose-free milk is perfectly safe, but still not a substitute for meat.

Some houseplants are harmful to cats. The leaves of the Easter Lily can cause permanent and life-threatening kidney damage to cats. Philodendron are also poisonous to cats. Cat Fancy has a full list of plants harmful to cats.

Some cats have a fondness for catnip, which is sensed by their olfactory systems. While they generally do not consume it, they will often roll in it, paw at it, and occasionally chew on it. The effect is usually relatively short, lasting for only a few minutes. After two hours or less, susceptible cats gain interest again. Several other species of plants (such as mint) cause this effect, to a lesser degree.

Cats can be fussy eaters, possibly due to the mutation which caused their ancestor to lose the ability to taste sugars. Unlike most mammals, cats can voluntarily starve themselves indefinitely despite being presented with palatable food, even a food which they had previously readily consumed. This can happen when the vomeronasal or Jacobson's organ becomes accustomed to a specific food, or if the cats are spoiled by their owners, in which case the cat will reject any food that does not fit the pattern it is expecting. It is also known for cats to merely become bored with their given food and decide to stop eating until they are tempted into eating again. Although it is extremely rare for a cat to deliberately starve itself to the point of injury, the sudden loss of weight can cause a fatal condition called hepatic lipidosis, a liver dysfunction which causes pathological loss of appetite and reinforces the starvation, which can lead to death within as little as 48 hours.

Additionally, cats have been known to develop a fondness for prepared human foods, normally preparations which are rich in proteins or fats. However, a diet consisting only of human food (even if high quality meat) is unlikely to contain the balanced nutrition required by the cat. Cats normally are good self-regulators of diet; however, unlimited access to food, or excessive human-food 'treats', will often lead to the cat becoming obese, particularly if it is older or more sedentary. This may lead to several health complications, such as diabetes, especially in neutered males. Such health conditions can be prevented through diet and exercise (playing), especially for cats living exclusively indoors.

Cats can also develop pica. Pica is a condition in which animals chew or eat unusual things such as fabric, plastic or wool. In cats, this is mostly harmless as they do not digest most of it, but can be fatal or require surgical removal if a large amount of foreign material is ingested (for example, an entire sock). It tends to occur more often in Siamese, Burmese, and breeds with these in their ancestry.

Toxic sensitivity

The liver of a cat is less effective at detoxification than those of other animals, including humans and dogs; therefore exposure to many common substances considered safe for households may be dangerous to them. In general, the cat's environment should be examined for the presence of such toxins and the problem corrected or alleviated as much as possible; in addition, where sudden or prolonged serious illness without obvious cause is observed, the possibility of toxicity must be considered, and the veterinarian informed of any such substances to which the cat may have had access.

For instance, the common painkiller paracetamol or acetaminophen, sold under brand names such as Tylenol and Panadol, is extremely toxic to cats; because they naturally lack enzymes needed to digest it, even minute portions of doses safe for humans can be fatal and any suspected ingestion warrants immediate veterinary attention. Even aspirin, which is sometimes used to treat arthritis in cats, is much more toxic to them than to humans and must be administered cautiously. Similarly, application of minoxidil (Rogaine) to the skin of cats, either accidental or by well-meaning owners attempting to counter loss of fur, has sometimes proved fatal.

In addition to such obvious dangers as insecticides and weed killers, other common household substances that should be used with caution in areas where cats may be exposed to them include mothballs and other naphthalene products, as well as phenol based products often used for cleaning and disinfecting near cats' feeding areas or litter boxes, such as Pine-Sol, Dettol (Lysol), hexachlorophene, etc. which, although they are widely used without problem, have been sometimes seen to be fatal. Antifreeze is particularly appealing to cats, and as little as a teaspoonful can be fatal.

Many human foods are somewhat toxic to cats; theobromine in chocolate can cause theobromine poisoning, for instance, although few cats will eat chocolate. Toxicity in cats ingesting relatively large amounts of onions or garlic has also been reported. Even such seemingly safe items as cat food packaged in pull tab tin cans have been statistically linked to hyperthyroidism; although the connection is far from proved, suspicion has fallen on the use of bisphenol A, another phenol based product as discussed above, to seal such cans.

Many houseplants are at least somewhat toxic to many species, cats included and the consumption of such plants by cats is to be avoided.

Habitat

The Wildcat, ancestor of the domestic cat, is believed to have evolved in a desert climate, as evident in the behavior common to both the domestic and wild forms. Wild cats are native to all continents other than Australia and Antarctica, although feral cats have become apex predators in the Australian Outback where they are menaces to wildlife. Their feces are usually dry, and cats prefer to bury them in sandy places. Urine is highly concentrated, which allows the cat to retain as much fluid as possible. They are able to remain motionless for long periods, especially when observing prey and preparing to pounce. In North Africa there are still small wildcats that are probably related closely to the ancestors of today's domesticated breeds.

Cats enjoy heat and solar exposure, often sleeping in a sunny area during the heat of the day. Cats prefer warmer temperatures than humans do. People start to feel uncomfortable when their skin's temperature gets higher than about 44.5 °C (112 °F), but cats do not start to show signs of discomfort until their skin reaches about 52 °C (126 °F).

Being closely related to desert animals, cats can easily withstand the heat and cold of a temperate climate, but not for extended periods. Although certain breeds such as the Norwegian Forest Cat and Maine Coon have developed heavier coats of fur than other cats, they have little resistance against moist cold (eg, fog, rain and snow) and struggle to maintain their 39 °C (102 °F) body temperature when wet.