Free Swimming and Exercise-Induced Pulmonary Hemorrhage in Endurance Horses: A Preliminary Study.

This research observes whether strenuous free-swimming exercise can cause Exercise-Induced Pulmonary Hemorrhage (EIPH) in endurance horses. The study concludes that such exercise does not appear to make the horses prone to EIPH.

Objectives and Method of the Study

• The primary goal of this research was to determine whether Exercise-Induced Pulmonary Hemorrhage (EIPH) might occur in endurance horses during intense free-swimming exercise. The conviction behind this was the anecdotal reports indicating that tethered swimming could lead to nasal bleeding (epistaxis) in horses, possibly as a result of EIPH.
• The research was an observational, prospective study involving 15 endurance horses. The method applied consisted of vigorous free-swimming workout sessions for the horses, each session entailing 5 rounds of 70 meters.

Data Collection and Evaluation

• Following the swimming, the researchers employed tracheo-bronchoscopic evaluations on the endurance horses. This helped them examine closely the respiratory tract (the trachea and bronchi) of the horses.
• These evaluations revealed low grade mucus scores, indicating minimal respiratory tract irritation. However, no tracheal blood (blood present in the windpipe, a possible indicator of EIPH) was observed.

Additional Analysis and Findings

• The researchers also performed bronchoalveolar lavage fluid analysis. This procedure involves washing a sample of cells and secretions from the bronchioles and alveoli (the smallest airways and air sacs) within the lung. It is used to determine inflammation, infection, or other conditions in the lung.
• The analysis revealed a low cellularity, indicating a small number of cells present. Furthermore, the median red blood cell count was only 271 cells/μL, which is well below the threshold of 1000 cells/μL required for a horse to be considered positive for EIPH.
• Based on these findings, the researchers concluded that free swimming does not appear to make endurance horses susceptible to EIPH after a typical free-swimming training session. This conclusion seemingly contradicts previous anecdotal reports of potential EIPH development in horses engaged in tethered swimming.