where cases of "pigeon fever" and "ulcerative lymphadenitis" have been recorded. This disease is spread between infected animals by vectors and through contamination of the environment with exudate from abscesses. Major bacterial spread occurs when superficial abscesses are broken open and release discharge that is then contacted by other animals during grooming, or contaminates feed, water, and bedding that other animals consume. These abscesses may break open spontaneously or be broken open on surfaces or during shearing. C. pseudotuberculosis can survive in soil for up to 8 months and contaminate bedding and indoor handling facilities for several weeks. In horses, arthropod vectors are considered a significant source of infection. As vector patterns change with warming temperatures, C. pseudotuberculosis in horses is re-emerging in the United States. This bacterial species has caused occasional cases of infection in people who work closely with infected small ruminants, resulting in similar swellings of the lymph nodes in the neck and groin. The most likely route of infection is direct contact with the infected animal or its raw products. Therefore, mostly farm workers and animal health workers are at risk. Cellular morphology, biochemistry, and identification C. pseudotuberculosis is a Gram-positive bacterium that can be either coccoid or filamentous rods, which can be organized into palisades. Metachromatic volutin granules containing phosphate can be seen in the rod form, but not the coccoid form when stained using Albert's or Neisser's methods. Other characteristics of this bacterium include being nonsporulating, noncapsulated, and possessing fimbrae, but it is immobile. This bacterium is grown at 37 °C under aerobic or anaerobic conditions, thus C. pseudotuberculosis is a facultative anaerobe. It forms dry, pale yellow colonies measuring 1–2 mm in diameter after incubation on solid media for 48 hours. Media containing serum or whole blood improve bacterial growth, and a band of beta-hemolysis tends to forms around bacterial colonies after 48–72 hours of incubation on blood agar. C. pseudotuberculosis forms clumps in fluid media. While strains of C. pseudotuberculosis are consistent in their morphology and growth on media, they show greater variation in biochemical properties such as fermenting ability. While they are unable to produce gas, all strains can use glucose, fructose, maltose, mannose, and sucrose to produce acid. Additional biochemical properties of this bacterium include being phospholipase D- and catalase-positive, oxidase-negative, and beta-hemolytic. Generally, two subtypes of C. pseudotuberculosis are known; the equi biovar affects horses and cattle, while the