Changes in plasma pH and blood and urinary macromineral concentrations in experimentally induced hypocalcemic cows with Na₂EDTA

Abstract

This study was performed to confirm the alterations of blood and urine parameters in artificially induced hypocalcemic cows. For a 2 × 2 cross-over design, four non-pregnant, non-lactating Holstein Friesian cows (623 ± 63 kg) were utilized. Cows in the treatment and control group were infused with ethylenediaminetetraacetic acid (Na 2 EDTA) solution and normal saline through an intravenous catheter for 3 hr, respectively. Laboratory analyses included complete blood cell count, plasma chemistry, blood gas analysis and urine chemistry. During the hypocalcemic period, abnormal signs were not observed clinically, hematologically nor biochemically either in groups. But, plasma calcium and magnesium concentrations continued to decrease throughout Na 2 EDTA infusion, and significant group differences ( P <0.05 or P <0.001) were detected until 5 hr after the initiation of infusion. Urinary excretions of these minerals were significantly reduced compared to the control group by 6 hr (Ca, P <0.05; Mg, P <0.001). Moreover, there is a significant group difference in the change in plasma pH at 1 hr after Na 2 EDTA infusion ( P <0.05) and maintained a decreased level until 6 hr. Consequently, the blood pH was diminished simultaneously with hypocalcemia and hypomagnesemia induction in cows infused with Na 2 EDTA. This phenomenon may be one of the mechanisms to recover normocalcemia including maximizing the effect of parathyroid hormone, however, further studies are needed to elucidate the mechanism to alter the blood pH in hypocalcemia.

Spontaneous alteration of blood pH by a bicarbonate buffer system during experimental hypercalcaemia in cows

“…Even though an acidic solution was administered, mildly alkaline blood pH was confirmed in the HYC group. This alteration was the opposite of the results of our previous study inducing the opposite state, hypocalcaemia, in which the deficit of Ca caused more acidic plasma pH, and probably resulted in the maximisation of the effect of PTH ( 9 , 10 , 12 ). As estimated in previous studies, there is a mechanism by which a decrease in blood pH results in an increase in the activity of PTH ( 9 , 10 , 13 ).…”

Comparison of the bovine blood gas parameters produced with three types of portable blood gas analyzers

“…The main purpose of this experiment was to confirm the correlation between the parameters of each analyzer. The correlation of the results between whole blood and plasma was confirmed in previous analyses, the plasma pH was approximately 0.2 higher than that of whole blood, and there were no significant differences in electrolytes and glucose between plasma and whole blood [ 17 ]. As a result of this experiment, the blood pH and pO 2 showed a high correlation between the three analyzers ( p < 0.001, r > 0.7), and pCO 2 also showed a correlation coefficient greater than 0.5.…”

“…In general, blood gas analysis is mainly performed using whole blood, especially arterial blood, and the most accurate gas analysis results can be obtained [ 10 16 ]. However, in the farm animals such as cattle, restraint for collecting arterial blood can be inconvenient, and since previous studies have confirmed that the results of venous blood reflect those of arterial blood, we collected the blood samples from the jugular vein [ 10 11 17 ]. In addition, in actual clinical practice, whole blood without anticoagulant is used for blood gas analysis, but in order to compare the three devices under the same conditions we used the plasma samples.…”

Induction of hypocalcaemia and evaluation of reticuloruminal motility using a three-axis accelerometer

“…Na 2 EDTA solution has been used in numerous studies of bovine hypocalcaemia (Jørgensen et al 1999;Mellau et al 2001), and when a chelating agent such as citrate or EDTA is administered, it diminishes ionised plasma Ca concentrations successfully in young and adult cattle (Desmecht et al 1995;Martinez et al 2014;Sasaki et al 2014;Ro et al 2020). In this study, all of the concentrations of blood samples collected at 0 h were in a normal range, but the infusion of Na 2 EDTA at a total amount of 48 g for 1 h was sufficient to induce hypocalcaemia in 600 kg cows.…”

“…1c). Parathyroid hormone (PTH) is secreted in response to decreased blood Ca concentrations, and the circulating concentration of Ca is increased by resorption from bone and reabsorption from the kidney (Kronqvist et al 2011;Blaine et al 2015;Ro et al 2020). The concentration of iP was also decreased after Na 2 EDTA infusion (Fig.…”