Observations on heaves. An asthma-like syndrome in the horse. 1964.

This research investigates the link between hay feeding in horses and asthma-like symptoms, known as ‘heaves’. The findings suggest that severe reactions occur due to hypersensitivity to a component of hay, resulting in lung or bronchial tree obstruction.

Background

• The study focuses on an ailment known as ‘heaves’ in horses, which is characterized by similar symptoms to asthma in humans. The researchers aimed to understand the relationship between hay feeding and the occurrence of heaves in horses, as well as the corresponding effects on their health, specifically their eosinophil count and sedimentation rate.

Methodology

• Six horses experiencing heaves were observed for the study. The changes in their eosinophil count and sedimentation rate during severe acute attacks were recorded.

Findings and Conclusion

• The observations pointed out a clear link between the feeding of hay and the onset of heaves attacks.
• Further, severe acute attacks were also accompanied by noticeable alterations in the eosinophil count (a type of white blood cell implicated in allergic reactions) and the sedimentation rate (a blood test measuring inflammation).
• The variation in the severity of heaves in connection to the feeding and withholding of hay led researchers to assume that these attacks could be the result of a temporary, obstructive lesion in the bronchial tree or lung. This lesion is caused by a hypersensitivity to a component in hay.
• In conclusion, the observations strongly indicated that heaves is a respiratory allergic disease in horses, similar to asthma in humans. Furthermore, the researchers discussed the association of heaves with pulmonary emphysema in horses, as an extension to their study.