Domestic pig

The domestic pig (Sus scrofa domesticus or only Sus domesticus), often called swine, hog, or simply pig when there is no need to distinguish it from other pigs, is a domesticated large, even-toed ungulate. It is variously considered a subspecies of the Eurasian boar or a distinct species. The domestic pig's head-plus-body-length ranges from 0.9 to 1.8 m (35 to 71 in), and adult pigs typically weigh between 50 and 350 kg (110 and 770 lb), with well-fed individuals often exceeding this weight range. The size and weight of a hog largely depends on its breed. Compared to other artiodactyls, its head is relatively long, pointed, and free of warts. Even-toed ungulates are generally herbivorous, but the domestic pig is an omnivore, like its wild relative. When used as livestock, domestic pigs are farmed primarily for the consumption of their flesh, called pork. The animal's bones, hide, and bristles are also used in commercial products. Domestic pigs, especially miniature breeds, are kept as pets. The domestic pig typically has a large head, with a long snout which is strengthened by a special prenasal bone and a disk of cartilage at the tip. The snout is used to dig into the soil to find food, and is a very acute sense organ. The dental formula of adult pigs is 3.1.4.33.1.4.3, giving a total of 44 teeth. The rear teeth are adapted for crushing. In the male the canine teeth can form tusks, which grow continuously and are sharpened by constantly being ground against each other. Four hoofed toes are on each foot, with the two larger central toes bearing most of the weight, but the outer two also being used in soft ground. Most domestic pigs have rather a bristled sparse hair covering on their skin, although woolly-coated breeds such as the Mangalitsa exist. Pigs possess both apocrine and eccrine sweat glands, although the latter appear limited to the snout and dorsonasal areas. Pigs, however, like other 'hairless' mammals (e.g. elephants, rhinos, and mole-rats), do not use thermal sweat glands in cooling. Pigs are also less able than many other mammals to dissipate heat from wet mucous membranes in the mouth through panting. Their thermoneutral zone is 16 to 22 °C (61 to 72 °F). At higher temperatures, pigs lose heat by wallowing in mud or water via evaporative cooling; although it has been suggested that wallowing may serve other functions, such as protection from sunburn, ecto-parasite control, and scent-marking. Pigs are one of four known mammalian species which possess mutations in the nicotinic acetylcholine receptor that protect against snake venom. Mongooses, honey badgers, hedgehogs, and pigs all have modifications to the receptor pocket which prevents the snake venom α-neurotoxin from binding. These represent four separate, independent mutations. Domestic pigs have small lungs in relation to their body size, and are thus more susceptible than other domesticated animals to fatal bronchitis and pneumonia.