Pasteurella is a genus of Gram-negative, facultatively anaerobic bacteria with coccoid or rod-shaped cells, belonging to the family Pasteurellaceae. Species such as Pasteurella multocida and Pasteurella haemolytica live as parasites and commensals in humans and animals, colonising the respiratory tract. They cause haemorrhagic septicaemia and pneumonia in cattle, pigs, sheep, and poultry, and wound infections in people bitten or scratched by animals, particularly cats. They are sensitive to most common antibiotics including penicillin, so treatment is usually straightforward if started promptly. In livestock, vaccination and good husbandry reduce losses, while in food contexts their presence signals the animal-origin contamination routes that hygiene must block.