Pearl Disease

Pearl Disease, an outdated name that initially referred to a specific form of disease of the peritoneum and pleura in cattle, in which small detached tumors form on the serous membranes, having some resemblance to pearls. After the tuberculous nature of these tumors was established by the discovery of Koch's bacilli in them, the name P. d. was transferred to all forms of tuberculosis in cattle and is still sometimes encountered in this sense, both in common usage and in agricultural literature. The designation of P. d. as a synonym for tuberculosis in cattle should be eliminated from both scientific and popular terminology. First, 'pearls' are found on the serous membranes not only in cattle but also in goats, horses, and other animals, in which the reactive formation of connective tissue around tuberculous foci with its subsequent transition into scar tissue occurs with such intensity that it leads to the detachment of individual nodges from their base on the serous membrane. Second, the term P. d. in practice misleads non-specialists when, during the slaughter of tuberculous cattle, they do not find 'pearls' (or 'peas'), but only changes in the parenchymal organs that have no external resemblance to pearls.