Brucellosis is a bacterial infection caused by numerous Brucella species that mostly affect cattle, swine, goats, sheep, and dogs. Humans typically contract the disease by direct contact with infected animals, consumption of contaminated animal products, or inhalation of airborne pollutants. Abortion or the birth of weak calves are the most prominent indicators in pregnant animals. Changes in the usual lactation period caused by abortions and delayed pregnancies may diminish milk output. Not all infected cows have abortions, but those who do usually have them between the fifth and seventh month of pregnancy. Brucellosis is a contagious, infectious, and communicable disease caused by bacteria of the genus Brucella that mostly affects cattle, bison, and pigs. Brucella primarily affects cattle, but goats, sheep, and horses are also susceptible. The incubation period can vary and is inversely related to the stage of pregnancy at the moment of exposure. Organisms are shed in milk and uterine discharges, and the cow may become sterile for a short period of time. Bacteria can be discovered in the uterus throughout pregnancy, uterine involution, and, in rare cases, for an extended period of time in the nongravid uterus. With the end of fluids following parturition, vaginal shedding virtually vanishes. Some previously aborted sick cows shed brucellae from the uterus during future normal parturitions.