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Intra‐ and Inter‐Day Variability in Plasma Bicarbonate Concentration in Sedentary Horses
Author(s) -
Bergstrom B,
Foreman J,
Foreman C,
Barger A
Publication year - 2014
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/evj.12267_47
Subject(s) - zoology , horse , blood sampling , medicine , analysis of variance , hay , venous blood , biology , paleontology
Alkalinizing agents have been given to horses before exercise to provide exogenous buffering effects. The objective of this experiment was to determine the intra‐ and inter‐day variability of resting plasma tCO 2 . The hypothesis was that tCO 2 would vary measurably during a multi‐day quarantine. Methods Eight acclimated sedentary horses had jugular venous samples collected into 10‐ml heparinized evacuated glass tubes 3 times daily (7 AM , 11 AM , and 3 PM ) for 5 consecutive days. Horses ate 5.3 kg alfalfa hay at both 7 AM and 3 PM after blood sampling. Plasma tCO 2 was determined within 1–3 hours of sampling using an automated chemistry analyzer. Mean tCO 2 for all 8 horses was calculated for each of the 15 sampling intervals. Results were compared by Repeated Measures ANOVA . When there was no apparent day‐to‐day effect, data for all horses were pooled by time‐of‐day (n = 40 samples for each of 3 times‐of‐day) and compared by the Student's t test to determine time‐of‐day effect. P<0.05 was considered significant. Results Mean tCO 2 over the 15 sampling intervals ranged from 28.9‐to‐31.6 mmol/L and was lower at 11 AM (Day 1) and 3 PM (Days 1, 3, and 4) compared to 7 AM on Day 1 (P<0.05). Individual plasma tCO 2 ranged over 4‐to‐7 units (low 26, high 34, widest range 26–32, narrowest 28–31). Mean pooled tCO 2 differed by time‐of‐day, with 11 AM (30.1 ± 0.2, P = 0.011) and 3 PM (29.8 ± 0.2, P<0.001) values lower than 7 AM values (31.0 ± 0.2). Conclusions Plasma tCO 2 differed significantly by time‐of‐day with considerable intra‐ and inter‐individual variability. Ethical Animal Research The study was approved by the U niversity of Illinois Institutional A nimal Care and U se C ommittee. Sources of funding: Fédération Equestre Internationale and Maria Caleel F und for Equine Sports Medicine R esearch. Support for Dr. Bergstrom was provided by the Merial V eterinary Scholars Program. Competing interests: none.