The effect of dipotassium EDTA and lithium heparin on hematologic values of farmed brown trout Salmo trutta (L.) spawners

Blood analysis is a very important and powerful diagnostic tool in animal health and welfare control. It is routinely performed in higher vertebrates, for which reference values are well established, but fish hematology still needs further research. Many intrinsic and environmental factors have profound impact on fish hematological values, making determination of reference values difficult. Additionally, fish blood usually requires the addition of an anticoagulant agent, because of short clotting times. The choice of anticoagulant is vital for obtaining reliable blood test values. In the present study, the impact of two common anticoagulants, K2EDTA (1.8 mg/ml) and lithium heparin (18 I.U./ml), on hematological values of farmed brown trout Salmo trutta spawners during the spawning season was investigated. Results of basic hematological analysis, such as packed cell volume (PCV), hemoglobin concentration (HGB), red blood cell count (RBC), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), and white blood cell count (WBC), were compared between these two compounds. Statistically significant differences were observed in PCV, MCV, and MCHC, whereas HGB, RBC, MCH, and WBC showed no such differences. These results suggest that lithium heparin gives more reliable results, because red blood cells in K2EDTA-treated samples have a tendency to swell. It is worth noting that ethylenediaminetetraacetic acid salt did not induce sample hemolysis in the present study.