Silicate pneumoconiosis and pulmonary fibrosis in horses from the Monterey-Carmel peninsula

Pneumoconiosis is generally associated with occupational (industrial) exposure or unusual behavior habits. Geographic features have been recognized in certain cases from arid or desert areas where soils are rich in silicates. This report summarizes our experience with nine cases of granulomatous pneumonia in horses presenting with exercise intolerance and various degrees of respiratory distress. All cases have originated from the Monterey-Carmel peninsula or the Carmel Valley of California; all cases have been spontaneous and an industrial association has not been recognized. Since animal populations are frequently used as indicators of human disease, this observation of equine disease may serve as a signal for a previously unrecognized environmental disease with potential human health implications.