A prospective study on a cohort of horses and ponies selected for participation in the European Eventing Championship: reasons for withdrawal and predictive value of fitness tests.

Background: Eventing is generally recognized as a challenging equestrian discipline and wastage figures for this discipline are relatively high. There is a need for information that provides insight into the causes of wastage and withdrawal from competition, for animal welfare and economic reasons. The aim of the present investigation was to conduct a prospective study following the entire national selection of event horses (n = 20) and ponies (n = 9) in the Netherlands that prepared for the European Championship in 2010 (ponies) and 2011 (horses), noting causes of withdrawal and monitoring fitness using standardized exercise tests (SETs), with heart rate (HR; beats/min), speed (V; m/s) and plasma lactate concentrations (LA; mmol/L) as measured parameters.

Results: In SET-I, performed at the beginning of the season, horses (n = 17) had a mean VLA4 (V at LA 4 mmol/L) of 10.3 ± 0.4 m/s with a mean V200 (V at 200 beats/min) of 11.4 ± 0.8 m/s and ponies (n = 9) a mean VLA4 of 7.8 ± 0.9 m/s and V200 of 9.6 ± 0.7 m/s. Before SET-II, performed six weeks before the European Championship, 16/20 horses and 6/9 ponies were withdrawn. The most common reason for withdrawal was locomotor injury (9/16 horses, 4/6 ponies; P < 0.001 and P = 0.011, respectively). Other reasons included an animal 'not meeting the competition criteria' (4/16 horses, 2/6 ponies) and being sold (3/16 horses). Animals were divided on the basis of VLA4 and recovery-HR during SET-I into good and average performers. Average performers were significantly more likely to be injured (50.0%) than good performers (0%, P = 0.05). In a subpopulation of ten horses, in which all condition training sessions were evaluated for HR and speed, HRpeak was significantly lower in horses that stayed sound (186 ± 9 beats/min) compared with horses withdrawn from training and competition because of injury (201 ± 5 beats/min; P = 0.016).

Conclusions: Of the national selection, 45% of all animals were unavailable for the European Championship because of locomotor injuries. Field tests were useful in assessing the potential injury risk, as individuals with better fitness indices (good performers) were less likely to become injured than average performers. Furthermore, monitoring of training sessions showed predictive value for future injuries, as horses withdrawn because of injury later on showed already higher peak HRs during condition training than horses that stayed sound. Therefore the increase in peak HR seemed to precede visible lameness in a horse.