Perilla ketone toxicity: a chemical model for the study of equine restrictive lung disease.

Perilla ketone was assessed for its usefulness as a model of equine restrictive pulmonary disease. Three ponies were given 18 mg/kg bodyweight synthetic perilla ketone in dimethyl-sulphoxide. Within 24 h of administration, respiratory rate, peak inspiratory and expiratory flow rates and minute volume were increased. By 48 h there was a significant decrease in tidal volume, and blood pH and base excess were also decreased but not outside normal limits. At necropsy there was congestion and oedema of the lungs. Histologically there was diffuse alveolar injury but no evidence of significant obstruction in bronchial or bronchiolar lumina. It is assumed that perilla ketone toxicity in ponies produces a restrictive disease without a significant obstructive component.