Focal mineralization and nonspecific granulomatous inflammation of respiratory mucous membranes in pigs.

Discrete mineralized foci and granulomatous inflammation occurred in the lamina propria mucosae of respiratory mucous membranes of adult pigs. Lesions were present in clinically healthy pigs of both sexes, including castrated males, fed various pelleted or non-pelleted diets. They were mainly in longitudinally corrugated mucosae of the dorsal wall of the trachea. Identical mineralization and inflammation occurred in the nasal cavity and, in decreasing frequency and intensity, in the thoracic trachea and bronchi. The lesions in respiratory mucous membranes occurred in pigs with and without mineralization in other organs. The distribution of lesions in the respiratory tract, and the higher frequency in pigs fed non-pelleted dusty feeds, suggest that focal mineralization was caused by inhaled particles of calcium salts.