Comparison between cavernous sinus and jugular vein as post mortem sampling sites for blood metabolic profiles in wild red deer (Cervus elaphus)

Collection from jugular vein (JV) or intrathoracic cavity is the traditional procedure for blood sampling dead wildlife, but it is often source of preanalytical biases. Cavernous sinus of dura mater (CS) is an alternative site for withdrawal that may help to solve these issues but it has been used only for serology, while no data are available for biochemistry. This work compares metabolic profiles from CS and JV blood in red deer Cervus elaphus, to evaluate the usability of CS for metabolic profiling. A total of 134 deer were sampled in the frame of a culling program within the Stelvio National Park (Central Italian Alps). Hemolysis was statistically lower in CS than JV with 88% vs 44% of samples suitable for biochemistry. Thirty-six couples of poorly hemolytic sera were used for biochemical analysis: total protein, albumin, urea, triglycerides, total cholesterol, non-esterified fatty acids (NEFA), betahydroxybutyrate (BOHB), calcium, and phosphorus. Statistical differences were found for protein, albumin, cholesterol, and calcium; agreement was found for urea, NEFA, BOHB, and phosphorus while for total protein, albumin, cholesterol, and calcium, CS showed lower concentrations with both constant and proportional biases. These results may be related to a higher impact of water dilution in CS. Although the lower protein concentration in CS cannot significantly influence the serological results, caution is required for potential false negative results when antibody levels are close to cut-off values. CS leads to a higher percentage of samples suitable for metabolic profiles but results should be compared with adequate reference intervals.