REFERENCE INTERVALS FOR D-DIMER CONCENTRATION, FIBRINOGEN CONCENTRATION, AND AUTOMATED PLATELET COUNT IN JUVENILE ASIAN (ELEPHAS MAXIMUS) AND AFRICAN (LOXODONTA AFRICANA) ELEPHANTS WITHOUT ELEPHANT ENDOTHELIOTROPIC HERPESVIRUS.

Elephant endotheliotropic herpesvirus hemorrhagic disease (EEHV-HD) is the leading cause of mortality in juvenile ex situ Asian elephants (Elephas maximus) and is increasingly reported as a cause of morbidity and mortality in juvenile African elephants (Loxodonta africana). A bleeding diathesis, with signs suggestive of disseminated intravascular coagulation (DIC), has been described in cases of EEHV-HD. Results of platelet count, fibrinogen concentration, and D-dimer concentration are included in the International Society on Thrombosis and Hemostasis (ISTH) overt DIC scoring system. The objective of this study was to establish reference intervals for these laboratory assays in healthy juvenile elephants in order to evaluate the ISTH DIC scoring system for these species. Twenty-four African and 20 Asian elephants, between 1 and 15 yr of age, were enrolled in this study. Blood samples were obtained from each individual at a single point in time for D-dimer concentration, platelet count, fibrinogen concentration, and EEHV qPCR. All EEHV qPCR results were negative. No significant difference existed between species for D-dimer concentration (P = 0.17) or platelet counts (P = 0.052). Asian elephants had significantly higher fibrinogen concentrations (320.05 ± 44.58 mg/dl; mean ± SE) compared with African elephants (256.13 ± 29.35 mg/dl, P < 0.001). Fibrinogen was significantly higher in male (273.89 ± 27.64 mg/dl) compared with female (245.47 ± 25.57 mg/dl) African elephants (P = 0.02). There was a moderately strong positive correlation between platelet count and age in African elephants (R = 0.51, P = 0.03). The other analytes did not differ significantly with age and sex for either species (P > 0.05). Reference intervals for D-dimer concentration, fibrinogen concentration, and automated platelet counts were determined for each species using the robust and the parametric methods. Results from this study provide the foundational knowledge required for the development of an overt DIC scoring system in juvenile elephants with EEHV-HD.