Comparison of Anticoagulants to Obtain Hematologic Values in Captive Bull Sharks (Carcharhinus leucas)
There are increasing numbers of elasmobranchs in captivity resulting in the need to closely monitor the general health of these species. Obtaining hematologic values for health assessment can pose unique obstacles, one of which is determining an appropriate anticoagulant.1-6 It has been suggested that heparin may not be as effective as EDTA in preventing clotting and that use of EDTA may result in cell lysis.3,6 There are no standard recommendations for anticoagulant use in elasmobranch blood analysis. In order to assess the differences between anticoagulants, blood was collected from five captive, wild-caught bull sharks using lithium heparin, EDTA and a mixture of both. A mixture of EDTA and heparin has been proposed to be more effective with less cell lysis then either used separately.6 Blood samples were collected from the caudal vertebral vein under manual restraint. Samples were immediately separated into three different anticoagulants: lithium heparin, dry EDTA, and a combination of heparin and liquid EDTA.5 Complete blood counts (CBCs) were performed from each sample within 6 hours of collection. Parameters assessed included differentials, hemoglobin via HemoCue® 201+analyzer (HemoCue, Inc., Lake Forest, CA), and smudged cell counts as an estimate of cell lysis. CBCs were compared using the student’s t-test. To estimate cell lysis, smudged cells were used as a percentage of total cell numbers. No significant differences in CBC or smudged cells were noted between the three anticoagulant types used. No advantage was noted with the EDTA/heparin mixture as has been previously reported.5 Both dry EDTA and heparin would be reasonable choices to use as anticoagulants when obtaining hematologic data in bull sharks.
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