Evaluation of clinical signs of disease, bronchoalveolar and tracheal wash analysis, and arterial blood gas tensions in 13 horses with chronic obstructive pulmonary disease treated with prednisone, methyl sulfonmethane, and clenbuterol hydrochloride.

This study assessed the effectiveness of three different treatments (prednisone, methyl sulfonmethane, and clenbuterol hydrochloride) for horses suffering from chronic obstructive pulmonary disease. It found that no significant changes were observed with regards to lung sounds, respiratory effort, arterial blood gas tensions or phagocyte function amongst other variables.

Research Method

• The study involved 13 horses with chronic obstructive pulmonary disease.
• Three different treatments were tested: Prednisone (7 horses); methyl sulfonmethane (6 horses); and clenbuterol hydrochloride (7 horses). A control group of 6 horses was also included.
• Each treatment period lasted for 10 days and each horse participated in two different groups. An 18-day treatment-free interval separated these periods.
• All horses were collectively accommodated in an outdoor pen and fed on a diet of alfalfa/grass hay.
• Various physical and laboratory variables were observed and recorded before, during, and at the end of each trial period. These included lung sounds, respiratory effort, anal movement, nasal discharge, temperature, respiratory rate, and heart rate, among others.

Research Findings

• There were no significant changes observed in lung sounds, respiratory effort, arterial blood gas tensions, tracheal wash or bronchoalveolar lavage cytologic findings, anal movement, nasal discharge, or phagocyte function in the horses.
• All horses experienced tachypnea (rapid breathing) and most of them had tachycardia (rapid heart rate).
• The median value for PaO2 (partial pressure of oxygen in arterial blood) was lower than normal across all horses.
• Negative linear correlation was observed between PaO2 and respiratory effort in the horses. That is, as the levels of oxygen in the blood (PaO2) decreased, the degree of respiratory effort increased.
• Most cytological findings from tracheal wash and bronchoalveolar lavage indicated a suppurative response, which is characterized by the body producing pus as a response to infection or injury.
• The findings suggest that none of the three treatments had a significant effect on the examined variables in horses with chronic obstructive pulmonary disease.