Reference Intervals for Hematology and Clinical Chemistry for the African Elephant (Loxodonta africana)

The African elephant (Loxodonta africana) is listed as vulnerable, with wild populations threatened by habitat loss and poaching. Clinical pathology is used to detect and monitor disease and injury, however existing reference interval (RI) studies for this species have been performed with outdated analytical methods, small sample sizes or using only managed animals. The aim of this study was to generate hematology and clinical chemistry RIs, using samples from the free-ranging elephant population in the Kruger National Park, South Africa. Hematology RIs were derived from EDTA whole blood samples automatically analyzed (n = 23); manual PCV measured from 48 samples; and differential cell count results (n = 51) were included. Clinical chemistry RIs were generated from the results of automated analyzers on stored serum samples (n = 50). Reference intervals were generated according to American Society for Veterinary Clinical Pathology guidelines with a strict exclusion of outliers. Hematology RIs were: PCV 34-49%, RBC 2.80-3.96 × 10¹²/L, HGB 116-163 g/L, MCV 112-134 fL, MCH 35.5-45.2 pg, MCHC 314-364 g/L, PLT 182-386 × 10⁹/L, WBC 7.5-15.2 × 10⁹/L, segmented heterophils 1.5-4.0 × 10⁹/L, band heterophils 0.0-0.2 × 10⁹/L, total monocytes 3.6-7.6 × 10⁹/L (means for "regular" were 35.2%, bilobed 8.6%, round 3.9% of total leukocytes), lymphocytes 1.1-5.5 × 10⁹/L, eosinophils 0.0-0.9 × 10⁹/L, basophils 0.0-0.1 × 10⁹/L. Clinical chemistry RIs were: albumin 41-55 g/L, ALP 30-122 U/L, AST 9-34 U/L, calcium 2.56-3.02 mmol/L, CK 85-322 U/L, GGT 7-16 U/L, globulin 30-59 g/L, magnesium 1.15-1.70 mmol/L, phosphorus 1.28-2.31 mmol/L, total protein 77-109 g/L, urea 1.2-4.6 mmol/L. Reference intervals were narrower than those reported in other studies. These RI will be helpful in the future management of injured or diseased elephants in national parks and zoological settings.