C. pecorum is a species of Chlamydiaceae that lives on mucous membranes of the mouth and can infect other organs. It is an small, obligate intracellular gram negative bacteria that grows in eukaryotic cells. It has many characteristics of a gram negative bacteria but it differs in that it lacks peptidoglycan.
C. pecorum infects many mammalian hosts including cattle, goats, koalas, sheep and pigs. Because C. pecorum grows slowly within the natural host, actual disease syndromes are not as evident until later in the infectious process.