SAEVA Congress 2018 Proceedings | 12-15 February 2018 | ATKV Goudini Spa
When storage of samples is required ( eg overnight ), blood should be refrigerated . Storing at room temperature may result in increases in MCV and PCV , and perhaps reduced RBC numbers , due to swelling and rupture of erythrocytes . Hemoglobin concentration , however , is not affected by erythrolysis .
Performance Prediction . One of the primary reasons given for hematological examination of blood is to assist in the assessment of fitness , athletic ability and poor performance . Unfortunately , the validity of such assessments pertaining to fitness and ability remains in doubt , much of the problem in this regard lying in the desire to emphasize the positive aspects of the examination . One study has claimed that populations of winners had RBC , PCV , and Hb concentrations that exceeded the population mean , and another suggested that in Australia , the best horses had a PCV of 40-45 %, RBC of 9-11 x 10 6 / ml , and Hb concentration of 14-16 g / dl . While this may have been the case , it must be realized that in each report there were many horses with similar erythrocytic indices which had poor or moderate racing careers . In addition , a number of successful horses have resting values for these parameters which fall outside these ranges , particularly below them .
Because of the lability of the erythrocyte pool , the effects of hematinic agents are very difficult to evaluate , and the administration of these agents and others to healthy horses , with the express purpose of producing erythrocytic parameters in a given range is ill-advised .
Rather than attempting to attach positive information to the hematological evaluation , the veterinarian may be better served to emphasize the negative . Detection of anemias , and possibly polycythemias , may help to identify horses which are unlikely to perform well . One study concluded that any blood count below one standard deviation from the population mean was suboptimal , and horses displaying such characteristics were unlikely to run well . It may be reasonable to hypothesize that if a value for a given individual falls more than one standard deviation below its mean ( determined from at least 6 different samples ), then the horse ' s performance may decrease .
While abnormalities of the blood count are often incriminated as the causes of poor performance , in many cases the changes represent only normal biological variation . However , in overtrained trotters with poor racing performance there can be red cell hypervolemia . These horses fall well below average racing performers despite having high Hb concentrations . Overtrained horses can also have significantly lower basal plasma cortisol values and the response to ACTH administration may be attenuated , although evidence for this is highly variable . These differences might be explained by the observation that , with rest , the plasma response of the adrenal gland to ACTH can improve . These combined mechanisms may give some explanation for the clinical improvement that overtrained horses are said to show after having 1-2 gallons of blood removed .
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