Clinical signs of EGUS are usually subtle and non-specific. What is the evidence of the effect of EGUS on performance?
- In one study, EGUS was reported as a cause of poor performance in four racehorses (decreased willingness to gallop or recent history of slowing or stopping toward the end of races, Franklin et al., 2008);
- In other work, Thoroughbred horses with experimentally induced ESGD had decreased aerobic capacity, stride length and time to fatigue (Nieto et al., 2009);
- More recently, the negative impact of EGUS on performance of Standardbreds was reported. The values of VLa4 (speed at a blood lactate of 4mmol/L) and V200 (speed at heart rate of 200bpm) were lower in horses with higher ESGD grades, suggesting an impairment in aerobic capacity (Lo Feudo et al., 2022).
The mechanisms by which EGUS affects performance have not been clarified. One possible explanation is that abdominal discomfort may prevent affected horses from making their best effort during training/racing. Pain may also affect diaphragmatic excursion during breathing causing an earlier switch to anaerobic metabolism. Decreased feed intake may also result impacting condition and performance.