• horse;
  • bronchoalveolar lavage;
  • exercise induced pulmonary haemorrhage;
  • training


Although bronchoalveolar lavage (BAL) has become a commonly used technique for evaluation of pulmonary cytology and there have been many reports on horses at rest and in race training, there have ben no longitudinal studies where cytological results have been assessed during a training programme which involved increases in training intensity. In this study, 10 Thoroughbred horses were trained on a treadmill for a period of 12 weeks and were divided into 2 groups, one group (FAST) being trained at intensities to produce whole blood lactate concentrations in the range 4–8 mmol/l while the other group (SLOW) were trained at half the intensity of the FAST group. The training speeds for the FAST group ranged from 8–11 m/s whereas that for the slow group ranged from 3–6 m/s. Horses were trained for 6 days/week over daily distances of 1000–3600 m. Bronchoalveolar lavage samples were collected from each horse during weeks 1, 3, 6, 8, 10 and 12. The BAL samples were analysed and compared with respect to changes in cytology occurring throughout the period of training. The results of the study indicated that intensity and duration of exercise may have an effect on the development and severity of exercise induced pulmonary haemorrhage (EIPH), as determined by the absolute count and the percentage of erythrocytes returned in a BAL sample. This appears to be especially true when training at high intensities. However, the low levels of EIPH detected in the horses were not sufficient to cause a measurable loss of exercise performance or lowering of the horses' maximal oxygen uptake during exercise. Low intensity training was noted to have very little effect on the observed BAL cytology.