Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles.
Authors: Mellor David J, Beausoleil Ngaio J
Journal: Animals : an open access journal from MDPI
Summary
# Editorial Summary: Equine Breathing, Bridles and Welfare During Exercise During intense exercise, horses operate at the physiological edge of their cardiorespiratory capacity, making them vulnerable to any factor that further compromises airway function or impedes gas exchange. Mellor and Beausoleil's 2017 review synthesises equine respiratory physiology literature to examine how management practices—particularly rein tension and bit use—alongside respiratory pathology might trigger three distinct types of breathlessness in working horses: unpleasant respiratory effort, air hunger, and chest tightness, each arising from a mismatch between ventilatory demand and actual respiratory capability. Rein configurations that reduce the jowl angle and bits that disrupt negative oropharyngeal pressure both increase upper airway resistance and can trigger a cascade of pathophysiological changes extending to the lower airways, potentially worsening the hypoxaemia, hypercapnia and acidaemia that already challenge healthy horses during strenuous work. Beyond respiratory mechanics, the authors highlight that most horses demonstrate clear behavioural aversion to bits—ranging from mild irritation to significant pain—representing a substantial welfare concern independent of performance implications. Whilst direct comparative studies between bitted and bitless bridles remain absent, the evidence suggests that avoiding bridle configurations and bit types that mechanically obstruct the airway or cause oral discomfort may meaningfully reduce breathlessness intensity during athletic effort, warranting targeted investigation and potential revision of training and competition practices.
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Practical Takeaways
- •Consider bitless bridles as a potential welfare improvement, particularly for horses showing signs of respiratory compromise or bit aversion during exercise
- •Be aware that tight rein tension reducing jowl angle during ridden work can impair airflow and exacerbate respiratory distress in strenuous exercise
- •Assess horses for behavioural signs of bit-related discomfort and respiratory aversion, as these indicate potential pathophysiological effects on breathing capacity and welfare
Key Findings
- •Rein use that reduces jowl angle impairs upper airway flow and increases flow resistance during exercise
- •Three forms of breathlessness can occur in ridden horses: unpleasant respiratory effort, air hunger, and chest tightness when ventilatory drive exceeds respiratory response adequacy
- •Bits may disrupt negative pressure maintenance in the oropharynx, potentially allowing soft palate obstruction and causing significant breathlessness
- •Most horses show clear behavioural aversion to bits, ranging from mild irritation to severe pain, representing a significant welfare issue