title: Haematological response to racing and training exercise in Thoroughbred horses, with particular reference to the leucocyte response.
abstract: The haematological response to racing and to fast and slow training exercise was investigated in studies involving two populations of horses which differed widely in geographical location, climatic factors and management (Newmarket and Hong Kong). The well documented elevations in erythrocyte parameters were demonstrated and changing responses in leucocyte parameters, resulting in variations in the neutrophil to lymphocyte (N/L) ratio were described. It was shown that the immediate response to the anticipation or stress of exercise was a decrease in N/L ratio in association with an increase in lymphocyte numbers. The magnitude of the lymphocyte increases was similar in the two populations of horses producing a reversal of the N/L ratio (lymphocytes predominating) in the British but not the Hong Kong horses, owing to the higher resting ratio of the latter population. At 3 and 4 h after exercise, an increase in N/L ratio occurred in association with an increase in neutrophils and decrease in lymphocytes. All parameters had returned to resting level by 6 h following exercise. Those and the many other factors associated with alterations in equine N/L ratios are discussed in terms of the need for care when interpreting the results of haematological examinations.
mesh_terms: D000818:Animals; D002980:Climate; D004739:England; D004906:Erythrocyte Count / Q000662:veterinary; D006454:Hemoglobins / Q000032:analysis; D006723:Hong Kong; D006736:Horses / Q000097:blood* / Q000235:genetics / Q000502:physiology; D007958:Leukocyte Count / Q000662:veterinary; D007962:Leukocytes / Q000166:cytology*; D005082:Physical Exertion; D012420:Running
chemical_list: D006454:Hemoglobins