Pet food is plant or animal material intended for consumption by pets. Typically sold in pet stores and supermarkets, it is usually specific to the type of animal, such as dog food

Dog food

Dog food refers to food specifically intended for consumption by dogs. Though technically omnivorous, dogs exhibit a natural carnivorous bias, have sharp, pointy teeth, and have short gastrointestinal tracts better suited for the consumption of meat...

 or cat food

Cat food

Cat food is food intended for consumption by cats.As with all species, cats have requirements for specific dietary nutrients, rather than ingredients. Certain nutrients, including many vitamins and amino acids, are degraded by the temperatures, pressures and chemical treatments used during...

. Most meat used for non-human animals is a by-product of the human food industry, and is not regarded as "human grade."

Four companies—Procter & Gamble

Procter & Gamble

Procter & Gamble is a Fortune 500 American multinational corporation headquartered in downtown Cincinnati, Ohio and manufactures a wide range of consumer goods....

, Nestlé

Nestlé

Nestlé S.A. is the world's largest food and nutrition company. Founded and headquartered in Vevey, Switzerland, Nestlé originated in a 1905 merger of the Anglo-Swiss Milk Company, established in 1867 by brothers George Page and Charles Page, and Farine Lactée Henri Nestlé, founded in 1866 by Henri...

, Mars

Mars, Incorporated

Mars, Incorporated is a worldwide manufacturer of confectionery, pet food, and other food products with US$30 billion in annual sales in 2010, and is ranked as the 5th largest privately held company in the United States by Forbes. Headquartered in McLean, unincorporated Fairfax County, Virginia,...

, and Colgate-Palmolive

Colgate-Palmolive

Colgate-Palmolive Company is an American diversified multinational corporation focused on the production, distribution and provision of household, health care and personal products, such as soaps, detergents, and oral hygiene products . Under its "Hill's" brand, it is also a manufacturer of...

—are thought to control 80 percent of the world's pet-food market, which in 2007 amounted to US$

United States dollar

The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

 45.12 billion for cats and dogs alone.
Cat and dog food sales exceeded £1.4 billion in the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

 and US$

United States dollar

The United States dollar , also referred to as the American dollar, is the official currency of the United States of America. It is divided into 100 smaller units called cents or pennies....

14.3 billion in the United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 in 2005.