Evaluation of 3 handheld portable analyzers for measurement of L-lactate concentrations in blood and peritoneal fluid of horses with colic

Evaluation of peritoneal l-lactate concentration in horses in the early post-partum period

BACKGROUND

Peritoneal fluid lactate concentration is an important diagnostic tool in horses with abdominal pain. Information on peritoneal lactate concentrations is lacking following parturition in the mare.

OBJECTIVES

To compare blood and peritoneal lactate concentrations in a population of mares within 36 h post-partum, report a normal reference range and identify any impact of retained foetal membranes (RFMs).

METHODS

This is a retrospective study evaluating healthy mares from which blood and peritoneal samples had been obtained within 36 h of parturition. Exclusion criteria included signs of abdominal pain within this period. Data was interrogated for normality using a Shapiro-Wilk test. Wilcoxon signed-rank test and Bland-Altman analysis were used to compare blood and peritoneal lactate concentrations. Linear regression was used to compare age and breed data with peritoneal lactate concentrations. Significance was defined as p < 0.05.

RESULTS

Forty mares met the inclusion criteria. Mean age was 12.6 ± 4.1 years, and most mares were multiparous (65%). Peritoneal lactate ((1.2 (IQR = 0.9-1.6) mmol/L) was increased compared to blood lactate concentration (0.7 (IQR = 0-1.1)mmol/L; p < 0.001). Plasma total protein (TP) concentrations were 68 (IQR = 64-74) g/L and peritoneal protein concentrations 8 (IQR = 4-9.7) g/L. Six mares developed RFM. The median fold-increase in peritoneal lactate concentration compared to blood lactate concentration was 0.9 (IQR: 0.01-1.7; range: 0-2.5). The reference range for peritoneal fluid lactate concentration was 0-2.5 mmol/L.

CONCLUSION

Peritoneal lactate concentrations in healthy post-partum mares remained within the normal reference range and were not influenced by RFM or parturition. Increased peritoneal lactate in this group warrants further investigation.

Early Identification of Intestinal Strangulation: Why It Is Important and How to Make an Early Diagnosis

Horses with colic caused by intestinal strangulation can have an excellent outcome with early surgical correction of the obstruction. The expense associated with surgery is typically less with early lesion correction. The challenge is making an early diagnosis of intestinal strangulation. Although for some horses with a strangulating obstruction, the need for surgery is made based on severe colic signs or lack of response to analgesia, in other horses, it is less obvious. Signalment, history, and meticulous physical examination, combined with some targeted diagnostic procedures can help with early diagnosis of intestinal strangulation. Improving the outcome of these horses requires diligence and a team-based approach from the owner or caregiver, primary care veterinarian, and specialists.

Management of Colic in the Field

Colic is one of the most frequent emergencies necessitating veterinary attention. Referral is not an option in many cases; therefore, the ability to diagnose and treat colic in an ambulatory setting is paramount. Portable imaging and point-of-care testing has improved the ability to identify lesions and assess the patient's status. In cases when field management is the only option, practitioners should be aware of the various treatment options available.

Heart rate and blood lactate responses during the cross-country test of 2-star to 5-star eventing competitions

The objective of this retrospective study was to evaluate the physiological demands of cross-country competitions at different levels. Heart rates (HR) and post exercise blood lactate concentrations (LAC) measured between 2010 and 2019 in response to 1,463 cross-country competitions (437 at 2-star, 703 at 3-star, 313 at 4-star and 10 at 5-star level) in 294 horses were analysed. The effect of competition level, mean velocity, height profile, total distance, number of jumping efforts, climate, age, sex, percentage of Thoroughbred blood and performance level on HR, LAC, HR recovery and LAC disappearance rates was evaluated by Linear Mixed Effects Models. Mean HR and LAC significantly increased from 2-star to 4-star level (P<0.001). Each 30 m/min increase in mean velocity was associated with a 3 beats/min increase in HR (P<0.001) and a 41% increase in LAC (P<0.001) and each 30 m increase in cumulative elevation with a 2 beats/min increase in HR (P<0.001) and a 32% increase in LAC (P<0.001). Each 20 m increase in mean distance per jumping effort was associated with a 1 beat/min decrease in HR (P<0.01) and a 13% decrease in LAC (P<0.001). Compared to Warmbloods, horses with 75% Thoroughbred blood had 4 beats/min lower HRs (P<0.05) and 34% lower LAC values (P<0.001). Each 5 years increase in age was associated with a 4 beats/min decrease in HR (P<0.001, only in mares) and an 11% decrease in LAC (P<0.01). The HRs during the first 3 minutes of recovery were higher at warmer and more humid conditions (P<0.05). The rate of LAC disappearance was higher in horses with higher percentages of Thoroughbred blood (P<0.05).

Blood L-Lactate Concentration as an Indicator of Outcome in Roe Deer (Capreolus capreolus) Admitted to a Wildlife Rescue Center

Simple Summary

Roe deer are among the most frequent wild animals admitted to rescue centers in Italy. Reasons for admission include trauma, predation, starvation, and imprinting, with the final aim of hospitalization being full recovery and release into the wild for all cases. An accurate triage procedure is vital for predicting the outcome, to avoid unnecessary time spent in captivity, and an excessive allocation of time and resources on animals with a minimal chance of recovery. Since lactacidosis is often associated with death in hospitalized animals, and has been associated with poor prognosis in humans and domestic animals, we proposed an evaluation of blood L-lactate using a rapid whole blood test in order to predict the outcome of hospitalized roe deer. A cut-off of 10.2 mmol/L was identified as the best, in order distinguish animals with minimal chance of surviving and release. For these animals, humane euthanasia should be considered as an option.

Abstract

Roe deer (Capreolus capreolus) are among the most frequent patients of rescue centers in Italy. Three outcomes are possible: natural death, euthanasia, or treatment and release. The aim of the present study is to propose blood L-lactate concentration as a possible prognostic biomarker that may assist veterinarians in the decision-making process. Sixty-three roe deer, admitted to one rescue center in the period between July 2018 and July 2019, were sampled and divided into 4 groups according to their outcome: (1) spontaneous death (17 cases), (2) humanely euthanized (13 cases), (3) fully recovered and released (13 cases), and (4) euthanized being unsuitable for release (20 cases). In addition, blood samples from 14 hunted roe deer were analyzed as controls. Whole blood lactate concentrations were measured with a point of care lactate meter. Differences among groups were close to statistical significance (p = 0.51). A cut-off value of 10.2 mmol/L was identified: all the animals with higher values died or were humanely euthanized. The results suggest that roe deer with lactatemia higher than 10.2 mmol/L at admission, have a reduced prognosis for survival during the rehabilitation period, regardless of the reason for hospitalization and the injuries reported. Therefore, humane euthanasia should be considered for these animals.

Point-of-Care Diagnostics in Equine Practice

Point-of-care testing (POCT) refers to benchtop diagnostic modalities that have been translated into portable and easy-to-use formats suitable for patient-side use. Recent advances in diagnostic technology have allowed the development of a growing collection of POCT assays available to equine practitioners. Advantages include rapid results that reduce initial guesswork and promote diagnosis-targeted patient care, which may ultimately provide better clinical outcomes. Small handheld devices comprise most POCT technologies, providing qualitative or quantitative determination of an increasing range of analytes, including critical care analyzers and, more recently, hematology and immunology analyzers. This article discusses commercially available equine POCT.

Advances in Diagnostics and Treatments in Horses with Acute Colic and Postoperative Ileus

Differentiating between medical and surgical causes of colic is one of the primary goals of the colic workup, because early surgical intervention improves prognosis in horses requiring surgery. Despite the increasing availability of advanced diagnostics (hematologic analyses, abdominal ultrasound imaging, etc), the most accurate indicators of the need for surgery remain the presence of moderate to severe signs of abdominal pain, recurrence of pain after appropriate analgesic therapy, and the absence of intestinal borborygmi. Investigation of novel biomarkers, which may help to differentiate surgical lesions from those that can be managed medically, continues to be an active area of research.

Reliability of Lactate Scout Portable Analyzer in Agility Dogs During Multiple Measurements

The aim of this study was to evaluate the reliability of multiple measurements with Lactate Scout portable analyzer in dogs during treadmill exercise. Ten Border collies were involved in the study and blood samples were taken before, three times during and twice after the treadmill exercise. Lactate concentration was measured in duplicate, by Scout portable analyzer and the reference biochemical analyzer in the laboratory, and the obtained values were compared. There was a high and positive correlation between these two methods (r=0.96, p=0.003). The Lactate Scout analyzer reveals a high degree of agreement with the laboratory method and therefore can be valid for use in research of veterinary sports medicine and emergency veterinary medicine where multiple measurements of lactate concentrations are often needed.

Effect of Dexamethasone on Resting Blood Lactate Concentrations in Horses

Background

Blood lactate concentration is a marker of tissue perfusion and helps guide therapeutic interventions in critically ill horses. In both humans and dogs, administration of corticosteroids can increase blood lactate concentration, leading to type B hyperlactatemia. This effect could be a consequence of the impact of corticosteroids on glucose metabolism.

Objectives

To investigate the effects of daily IM dexamethasone administration on blood lactate and glucose concentrations in horses.

Animals

Nine healthy adult horses.

Methods

A randomized, blinded, controlled, cross‐over study design was used. Horses were randomly assigned to 1 of 2 groups, either receiving 0.05 mg/kg of dexamethasone IM or an equivalent volume of saline, daily for 7 days. Blood was collected to determine lactate and glucose concentrations at baseline, 2 hours after the daily injections and 24 hours after the last injection.

Results

Dexamethasone treatment had a statistically significant effect on lactate (P = .006) and glucose (P = .033) concentrations. The least squares mean lactate concentration was 0.93 mmol/L (95% CI: 0.87–0.99) in the dexamethasone group compared to 0.71 mmol/L (95% CI: 0.70–0.73) for the saline group. A positive relationship between blood lactate and glucose concentrations was identified, with a 0.07 mmol/L (95% CI: 0.05–0.09) increase in lactate concentration per unit increase in glucose (P < .0001) concentration.

Conclusions and Clinical Importance

Dexamethasone induces statistically significant increases in blood lactate and glucose concentrations in healthy horses. Awareness of the potential for corticosteroids to induce type B hyperlactatemia might be important in the management of critically ill horses receiving dexamethasone.

The Effect of Inadequate Presample Blood Volume Withdrawal from Intravenous Catheter and Extension Sets on Measured Circulating L-Blood Lactate Concentration in Horses Receiving Lactated Ringer's Solution

Background

Circulating l‐lactate concentration is commonly measured in hospitalized horses by sampling from indwelling intravenous (IV) catheters. However, there are no published evidence‐based recommendations to prevent contamination by lactated Ringer's solution (LRS).

Hypothesis

Withdrawing 10 mL of blood from the LRS‐containing extension set connected to the IV catheter before obtaining the sample for analysis should be adequate to obtain accurate measurement of blood lactate concentration (BLC).

Animals

Thirty‐three adult hospitalized horses receiving constant rate infusion of LRS.

Methods

Immediately after disconnecting the LRS, 5 sequential 5 mL blood samples were obtained by aspiration from an extension set connected to an indwelling IV catheter, followed by 3 samples collected by direct venipuncture of the contralateral jugular vein. Samples were analyzed with 1 portable blood lactate analyzer. A linear mixed model was used to examine differences in lactate concentrations among samples collected from the catheter and by direct venipuncture.

Results

After considering differences in age, breed, sex, and reason for hospitalization, BLCs were higher (P < .001) in the first and second 5 mL samples collected through the extension set/catheter than in all other extension set/catheter samples or the direct venipuncture samples. The largest difference observed between the third and subsequent catheter or venipuncture samples was 0.34 mmol/L with an upper 95% CI of 1.12 mmol/L.

Conclusions and Clinical Importance

Withdrawing 15 mL of blood from a LRS‐containing extension set connected to an IV catheter (5.9 mL total volume capacity) before obtaining the sample for blood lactate analysis is suggested to optimize accuracy of BLC measurements.

Lactate-guided conditioning program using variable exercise intensities improves fitness and alters muscle enzyme activity but not inflammatory response in horses

Blood lactate concentration ([LA]) response to exercise challenges can be used to assess fitness in horses. Most equine conditioning programs (CP) that have been studied are based on regular bouts of exercise of similar to increasing levels of intensity. We hypothesised that a lactate-guided CP implementing 2× weekly short-duration high-intensity exercise bouts and 1× weekly low-intensity longer-duration exercise bout effectively increases fitness in horses. Six untrained adult horses followed a 12 week CP that consisted of 2× weekly exercise on an equine treadmill (6% incline) for 25 min at a velocity at which [LA] was 4.0 mmol/l (VLA4.0) and 1× weekly for 45 min at a velocity at which [LA] was 2.5 mmol/l (VLA2.5). VLA2.5 and VLA4.0 were determined by incremental-step standardised-exercisetest (SET) before the CP and adjusted every 3 weeks. Blood was collected for [LA], creatine kinase (CK), aspartate aminotransferase (AST), serum amyloid A (SAA), and fibrinogen (Fb) before each speed increase and 30 min, 2, 4, and 24 h after termination of the SET, when [LA] was ≥4.0 mmol/l. Repeated-measures ANOVA was used for analysis. During each SET horses showed increases in heart rate (P<0.0001), packed cell volume (P=0.003), and [LA] (P=0.002). Throughout the CP, VLA2.5 increased from 5.6±0.2 to 6.7±0.3 m/s (P<0.05) and VLA4.0 increased from 6.0±0.2 to 7.4±0.3 m/s (P<0.01). CK, AST, SAA, and Fb did not increase following submaximal exercise. CK and AST activity were attenuated throughout the 12 week CP (P<0.05). This lactate-guided CP was effective at increasing fitness based on achieving higher speeds during the SETs and did not appear to have deleterious effects on the horses’ muscular system or inflammatory state.

Point-of-care devices for physiological measurements in field conditions. A smorgasbord of instruments and validation procedures

Point-of-care (POC) devices provide quick diagnostic results that increase the efficiency of patient care. Many POC devices are currently available to measure metabolites, blood gases, hormones, disease biomarkers or pathogens in samples as diverse as blood, urine, feces or exhaled breath. This diversity is potentially very useful for the comparative physiologist in field studies if proper validation studies are carried out to justify the accuracy of the devices in non-human species under different conditions. Our review presents an account of physiological parameters that can be monitored with POC devices and surveys the literature for suitable quantitative and statistical procedures for comparing POC measurements with reference "gold standard" procedures. We provide a set of quantitative tools and report on different correlation coefficients (Lin's Concordance Correlation Coefficient or the more widespread Pearson correlation coefficient), describe the graphical assessment of variation using Bland-Altman plots and discuss the difference between Model I and Model II regression procedures. We also report on three validation datasets for lactate, glucose and hemoglobin measurements in birds using the newly proposed procedures. We conclude the review with a haphazard account of future developments in the field, emphasizing the interest in lab-on-a-chip devices to carry out more complex experimental measurements than the ones currently available in POC devices.

The area under the curve of L-lactate in neonatal foals from birth to 14 days of age

BACKGROUND

Prior studies have shown the prognostic utility of measuring L-lactate in critically ill neonatal foals, both as single (at admission) and serial measurements. Greater prognostic sensitivity and specificity may be achieved by use of the area under the L-lactate versus time curve (LACArea ) over the first 24 hours of hospitalization, which captures both severity and duration of hyperlactatemia. Prior to application of this concept in sick equine neonates, a reference interval for LACArea should be determined.

METHODS

The concentration of lactate [LAC] was measured in blood obtained via direct jugular venipuncture from clinically normal foals on Days 1 (birth-24 h of age), 3, 7, and 14 following birth at 6-hour intervals for each 24-hour period. LACArea was calculated using the trapezoidal method. Differences in LACArea by Day were determined by MANOVA with a priori Bonferroni correction, P ≤ 0.05.

RESULTS

LACArea differed by Day (P = 0.001), being largest on Day 1, followed by Day 3. Days 7 and 14 were smallest and not different from each other.

CONCLUSION

LACArea decreases substantially and predictably over the first week of life in normal neonatal foals. Knowing how LACArea normally changes over the first 2 weeks of life will aid in future study of LACArea as it applies to sick neonatal foals, allowing for consideration of maturational changes potentially unrelated to disease.