Influence of head posture on the respiratory tract of healthy horses.

This research investigates the impact of prolonged raised head posture in horses, and its relationship with their respiratory health. The research found that keeping a horse’s head elevated for extended periods could lead to an increase in bacteria in their respiratory tract, potentially leading to respiratory disease.

Objective and Methodology

• The research aimed to determine the impact of head posture on the respiratory health of horses. It particularly focused on understanding the effects of prolonged periods of raised head posture, a common situation in confined stables.
• For this purpose, the researchers monitored 24 healthy mares that were unable to lower their heads for either 24 or 48 hours.
• The central focus of the research was on any changes in the tracheal aspirates (fluid removed from the lower airways of the lung), and signs of clinical respiratory disease that may coincide with these changes.

Key Findings

• The experiment resulted in increases in neutrophils and/or numbers of bacteria in lung fluid in 21 of the mares. Neutrophils are a type of white blood cell that represent the first line of defense against invading bacteria.
• Eight mares displayed signs of mild respiratory disease along with changes in the tracheal washes. In three mares, respiratory symptoms were accompanied by signs of systemic illness, which means that the body’s overall health was impacted.
• Notably, these symptoms reversed when the mares were allowed to lower their heads again, indicating a direct relationship between the head posture and respiratory health.
• Blood changes (absolute neutrophilia or an increase in neutrophils, and/or hyperfibrinogenamia or elevated levels of a protein that helps in blood clotting) were mild and prevalent in horses restrained for 48 hours.

Implications

• The findings infer that keeping a horse’s head raised for prolonged periods lead to an increased bacterial burden in their respiratory tract.
• They suggest the importance of the theory that postural drainage (a technique that uses gravity to promote the drainage of mucus from the lungs) may help clear bacteria from horses’ lungs.
• The study also discussed how these findings could relate to post-transportation pneumonia in horses, a common condition due to the common practice of transporting horses with their heads raised.