title: Physiological, metabolic and biochemical responses of horses competing in the speed and endurance phase of a CCI*****3-day-event.
abstract: The present study was undertaken to investigate physiological, metabolic, haematological and biochemical changes in horses competing in the Speed and Endurance test of a Concours Complet International (CCI)*****3-day-event held under FEI rules. A total of 28 horses competing in the Burghley Horse Trials Speed and Endurance test were selected to be monitored: 11 horses in 1993 and 17 horses in 1994. Of the 28 horses selected, 17 completed the Speed and Endurance test and went on to complete the showjumping test. Mean +/- s.d. shade temperature and relative humidity, black globe temperature and wind speed were 13 +/- 1 and 20 +/- 2 degrees C, 54 +/- 3 and 55 +/- 10%, 17 +/- 2 and 29 +/- 4 degrees C and 2.7 +/- 0.7 and 1.2 +/- 0.3 m/s, for 1993 and 1994, respectively. Mean heart rate during Phases A, B and D was not significantly different between years, but mean heart rate during Phase C and X was significantly higher in 1994. Mean (+/- s.d.) heart rate on Phase B and D for all horses in both 1993 and 1994 was 198 +/- 8 and 188 +/- 11 beats/min, respectively. Mean heart rate during Phase D showed a poor correlation with mean speed (r = 0.412). Total mean (+/- s.d.) weight loss from the start of Phase A to the end of Phase D was 15.5 +/- 6.1 kg in 1993 and 16.5 +/- 5 kg in 1994 and did not differ significantly between years. Following 14-18 h completion of Phase D, mean bodyweight was not significantly different from that at the start of Phase A in either year. Mean rectal temperature at the end of Phase D was 41 +/- 0.6 degrees C and 41.1 +/- 0.6 degrees C in 1993 and 1994, respectively (P > 0.05). Both the lowest (39.7 degrees C) and highest (41.8 degrees C) rectal temperatures were recorded at the end of Phase D in 1994. Plasma lactate concentrations at the end of Phase D were 8.5-38.5 mmol/l. The highest lactate concentration also coincided with the highest plasma glucose concentration (11.4 mmol/l) as well as the joint fastest time in either year, although overall lactate showed only weak correlations with mean speed on Phase D (r = 0.12, 1993; r = 0.58, 1994). While the Speed and Endurance test at CCI*****level run in a temperate climate presents a considerable challenge to the fitness and ability of the horses competing, the metabolic and physiological changes are not extreme. The majority of horses that finish the test appear to undergo a rapid and considerable degree of recovery and are able to present sound at the final inspection, take part in the showjumping test and complete the competition.
authors.affiliation: Physiology Unit, Equine Centre, Animal Health Trust, Newmarket, Suffolk, UK.
authors.forename: D J
authors.initials: DJ
authors.lastname: Marlin
authors.forename: P A
authors.initials: PA
authors.lastname: Harris
authors.forename: R C
authors.initials: RC
authors.lastname: Schroter
authors.forename: R C
authors.initials: RC
authors.lastname: Harris
authors.forename: C A
authors.initials: CA
authors.lastname: Roberts
authors.forename: C M
authors.initials: CM
authors.lastname: Scott
authors.forename: C E
authors.initials: CE
authors.lastname: Orme
authors.forename: M
authors.initials: M
authors.lastname: Dunnett
authors.forename: S J
authors.initials: SJ
authors.lastname: Dyson
authors.forename: F
authors.initials: F
authors.lastname: Barrelet
mesh_terms: D000818:Animals; D001219:Aspartate Aminotransferases / Q000097:blood; D001786:Blood Glucose / Q000032:analysis; D001798:Blood Proteins / Q000032:analysis; D001809:Blood Viscosity; D001831:Body Temperature; D003402:Creatine Kinase / Q000097:blood; D004573:Electrolytes / Q000097:blood; D005260:Female; D006339:Heart Rate; D006400:Hematocrit / Q000662:veterinary; D006454:Hemoglobins / Q000032:analysis; D006736:Horses / Q000097:blood / Q000502:physiology*; D019344:Lactic Acid / Q000097:blood; D007958:Leukocyte Count / Q000662:veterinary; D008297:Male; D010805:Physical Conditioning, Animal / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D012119:Respiration; D014887:Weather; D015431:Weight Loss / Q000502:physiology
chemical_list: D001786:Blood Glucose; D001798:Blood Proteins; D004573:Electrolytes; D006454:Hemoglobins; D019344:Lactic Acid; D001219:Aspartate Aminotransferases; D003402:Creatine Kinase