Clinico-Pathological Effects of Atmospheric Ammonia Exposure on Horses

Abstract

To clarify the effects of ammonia on the respiratory tract during trailer transports, horses in stalls were exposed to either 2-17 ppm (horse No. 1), which is a level similar to the interior vehicle environment, or 40-130 ppm (horse No. 2) of gaseous ammonia for 40 hr. Clinically, coughing and hypersecretion of nasal discharge, but no significant hematological changes, were observed in the exposed horses. Morphologically, swelling of the tip of cilia in the tracheal epithelium was observed in horse No.1. In contrast, marked changes in the form of lost cilia and degenerative cytoplasmic change of the tracheal epithelium were observed in horse No.2. These histological changes suggest a direct effect of ammonia gas on the respiratory tract.