Objective To describe the clinical and clinicopathologic abnormalities in endurance horses eliminated from competition and requiring emergency medical treatment. Design Retrospective study over a 2-year period (2005-2006). Ten horses that successfully completed the ride in 2006 were included for comparison. Setting Temporary equine emergency field hospital. Animals All horses (n=30) that were removed from endurance competition and treated for a metabolic abnormality were studied. Interventions Horses were treated with IV fluids and analgesics. Monitoring included lab work (PCV, total protein, and electrolytes) and serial physical examinations. Statistical analysis included descriptive statistics and parametric and nonparametric comparisons (ANOVA, Friedman's test, and Kruskal-Wallis) where appropriate. Measurements and Main Results The clinical diagnoses identified included colic, esophageal obstruction, poor cardiovascular recovery, myopathy, and synchronous diaphragmatic flutter. As a group, these sick horses had lower plasma chloride and potassium and higher total plasma protein concentrations as compared with 10 healthy horses that successfully completed the ride (P < 0.05, < 0.01, and < 0.05 for chloride, potassium, and total protein, respectively). Horses with colic had a lower PCV as compared with horses with poor recovery and those with synchronous diaphragmatic flutter (P < 0.05). All horses, including colics, were treated medically and discharged to owners. Conclusions Based on the results of this study, the prognosis for horses requiring emergency veterinary treatment after being removed from endurance competition (for metabolic reasons) appears to be good if horses are withdrawn from competition under the same criteria outlined in this study. Biochemical abnormalities tend to be mild and do not necessarily aid in delineating sick horses from successfully completing horses. None of the horses with gastrointestinal disease required abdominal surgery.
