Stability of Hematological Parameters in Woodland Caribou ( Rangifer tarandus caribou ) Blood Stored at 4 ° C

Eighteen free-ranging female woodland caribou were captured in northern Alberta in January and February 1993. Blood was collected into ethylenediaminetetraacetate (EDTA) tubes which were packaged in coolers containing ice packs, and transported to the laboratory where they arrived within 48 hrs of collection. Complete blood counts (CBC) were performed on five consecutive days to assess the stability of hematological parameters. Average values of hematocrit (HCT), mean cell hemoglobin (MCH), mean cell volume (MCV), red cell distribution width (P-J3W), white blood cell count (WBC), and red blood cell count (RJ3C) remained stable with no statistically significant changes occurring during 5 days of post-collection storage at 4°C. Mean PvBC values exhibited significant differences (p<0.05) between geographic locations. Mean platelet volume (MPV) increased significantly (p<0.001) with storage time, while platelet (PLT) values decreased (p<0.001) over time and were significantly different (p<0.01) between locations. For optimal hematological results, it is recommended that sample analysis be performed within 24 hours of blood collection; however, i f caribou blood samples are properly stored at 4°C, useful information may be obtained from stable parameters up to 5 days following collection.


Introduction
Hematological analysis, in conjunction with other screening procedures, provides valuable information when assessing animal health (Jain, 1986).For complete blood counts, it is generally agreed that blood constituents in EDTA remain stable for 24 hours at 4°C (Brittin et al, 1969;Cohle et al, 1981;Lampasso, 1968).However, when blood samples are collected from wild animals living in remote areas, transportation time to analytical laboratories may exceed 24 hours.
Because hematological values are often used for screening purposes, it is critical to determine their stability over time, under field conditions.Although the majority of hematological constituents in human blood remain stable for up to 5 days following collection (Cohle et al, 1981), using these guidelines for wildlife blood could be misleading.The objective of this study was to determine the stability of hematological parameters in woodland caribou blood stored at 4°C.

Materials and method
Study area, blood collection and transportation A total of eighteen female woodland caribou were captured by aerial net gun technique (Barret et al., 1982) during January and February of 1993 in the following two northern Alberta areas: between 55°30'N and 56 0 15'N, and 111°15'W and 112°35'W (referred to as location 1); and between 55°10'N and 55°40'N, and 112°42'W and 113°30'W (referred to as location 2).The animals were physically restrained without the use of an anaesthetic.Blood was collected from the superficial digital veins directly into 7-mL tripotassium EDTA Vacutainer tubes (0.081 mL of a 15% solution of tripotassium EDTA, Becton Dickinson & Co., Rutherford, NJ, USA) using 18-gauge needles (Becton Dickinson & Co., Rutherford, NJ, USA) After collection, blood tubes were wrapped in paper towels (to insulate from freezing), packed in a styrofoam cooler containing ice packs, and transported by courier to the Animal Pathology Laboratory at the Alberta Environmental Centre.The blood samples were received and analyzed within 24 to 48 hours of collection.

Hematological analysis
Prior to analysis, all samples were mixed at room temperature (22°C) for 10 to 15 minutes on a rocker (AMES Aliquot Mixer.Ames Division, Miles Laboratories Inc., Elkhart, IN, USA) which tilts back and forth at 18 cycles per minute.Hematological determinations including white blood cell count (WBC), red blood cell count (RBC), hemoglobin (HGB), hematocrit (HCT), mean cell hemoglobin (MCH), mean cell volume (MCV), mean cell hemoglobin concentration (MCHC), platelets (PLT), red cell distribution width (RDW), and mean platelet volume (MPV) were performed on a Coulter Counter S-Plus IV (Coulter Electronics, Inc. Hialeah, FL, USA) within 24 hours of collection (day 1).The samples were kept refrigerated at 4°C, and were reanalyzed every 24 hours for four consecutive days (days 2 to 5).All samples were analyzed in duplicate.

Statistical analysis
Least square mean estimates of location, time, and location-by-time were obtained by fitting blood data using a repeated measures analysis of variance model coded in SAS version 6.08 software (SAS Institute Inc., Cary, NC, USA).Time (days=l, 2, 3, 4 and 5) was the repeated factor in the model."Animals within locations" was used as the error term to calculate F-values to test for location effect.The overall mean square error was used for testing time and location-by-time effects.

Results
The average values for WBC, HCT, MCH, MCV and PvDW did not change significantly (p<0.05) with storage time or between collection locations 1 and 2 (Table 1).The values for MPV did not differ between the two locations, but increased signifi- Values with a superscript * are significantly different (p<0.05) from the mean on day 1.Hematological determinations on day 1 were performed within 24 hours of blood collection.
candy (p<0.001) with storage time.Values for HGB on day 5 showed a small but statistically significant change (p<0.001).The RBC values showed differences between locations (p<0.05),but did not change with storage (Table 2).The PLT values differed between locations (p<0.01), and with storage time (p<0.001).Platelet values from location 1 decreased 26% between day 1 and day 5; those in location 2 decreased 11%.The values of MCHC on days 3 and 4 were significantly greater than on day 1 (p<0.05)for location 1.However, values on day 2 through day 5 were not different from day 1 for location 2.

Discussion and conclusion
This study found that HCT, RBC, WBC, MCV, MCH and RDW values remain stable in female woodland caribou blood stored ar 4°C, for 5 days following collection; hemoglobin values remain stable for 4 days.Platelet numbers decreased and platelet size increased, suggesting that platelet aggregation occurred with storage.Cohle et al. (1981) found that platelet numbers in blood from healthy human donors were stable for 5 days following collection.
The differences in RBC and PLT values between locations suggest that there may be a location effect for some hematological parameters.
Results from this study indicate that caribou blood samples, when handled under our specified conditions of collection and storage, provide useful information for most hematological parameters up to 5 days following blood collection.Values with a superscript * are significantly different (p<0.05) from the mean on day 1.Hematological determinations on day 1 were performed within 24 hours of blood collection.

Table 1 .
Mean ± standard error of hematology parameters of female woodland caribou from two locations in northern Alberta, on day 1 through day 5 of blood storage at 4°C. (Values having no mean differences between locations).

Table 2 .
Mean ± standard error of hematology parameters of female woodland caribou from two locations in northern Alberta, on days 1 through 5 of blood storage at 4°C. (Values having mean differences between locations)