Validation and prognostic value of plasma lactate measurement in bovine respiratory disease

Correlation between L-Lactate Concentrations in Beef Cattle, Obtained Using a Hand-Held Lactate Analyzer and a Lactate Assay Colorimetric Kit

Simple Summary

Lactate is a metabolite used in animal research as an indicator of muscle fatigue; therefore, it has been used as an indicator of cattle response to long distance transportation. The aim of this study was to assess the relationship of L-lactate concentrations measured using a Lactate Scout+ hand-held analyzer and a traditional lactate assay colorimetric kit. Blood samples were collected from 96 steers prior to loading and after 36 h of transportation, and prior to reloading and after an additional 4 h of road transportation, and on d 1, 2, 3, 5, 14, and 28 after transport. The Lactate Scout+ hand-held analyzer strip was dipped in blood at the time of sampling, while blood samples were collected into sodium fluoride tubes for use in the colorimetric analysis. Correlations were calculated to assess the strength of the relationship between the L-lactate concentrations measured between methods. The strength of the correlation and the level of statistical significance varied over the observed time points, while the correlation for the pooled data was weak. Based on the low strength of the correlation, the Lactate Scout+ analyzer is not a suitable alternative to a colorimetric assay for measuring L-lactate in transported cattle.

Abstract

Lactate is a product of anaerobic glycolysis, used in animal research as an indicator of muscle fatigue. Therefore, it has been used as an indicator of cattle response to long distance transportation. The aim of this study was to assess the relationship of L-lactate concentrations measured using a Lactate Scout+ analyzer and a traditional lactate assay colorimetric kit. Blood samples were collected by venipuncture from 96 steers (Black or Red Angus × Hereford/Simmental and Black or Red Angus × Charolais; 247 ± 38.2 kg BW) prior to loading (LO1) and after 36 h of transport, and prior to reloading and after an additional 4 h of road transportation, and on d 1, 2, 3, 5, 14, and 28 after transport. The Lactate Scout+ analyzer strip was dipped in blood at the time of sampling, while blood samples were collected into sodium fluoride tubes for use in the colorimetric analysis. Pearson correlations were calculated to assess the strength of the relationship between the experimental methods for the quantification of L-lactate concentrations. The magnitude and direction of the correlation, and the level of statistical significance varied over the observed time points, ranging from r = −0.03 (p = 0.75; LO1) to r = 0.75 (p < 0.0001; d 3). The correlation for the pooled data was weak but statistically significant (r = 0.33, p < 0.0001). Based on the low magnitude of the correlation due to variability across sampling time points in this study, the Lactate Scout+ analyzer is not a suitable alternative to a lab-based assay (considered the gold standard) for measuring L-lactate in transported cattle.

Diagnosis of Bovine Respiratory Disease in feedlot cattle using blood 1H NMR metabolomics

Current diagnosis methods for Bovine Respiratory Disease (BRD) in feedlots have a low diagnostic accuracy. The current study aimed to search for blood biomarkers of BRD using ¹H NMR metabolomics and determine their accuracy in diagnosing BRD. Animals with visual signs of BRD (n = 149) and visually healthy (non-BRD; n = 148) were sampled for blood metabolomics analysis. Lung lesions indicative of BRD were scored at slaughter. Non-targeted ¹H NMR metabolomics was used to develop predictive algorithms for disease classification using classification and regression trees. In the absence of a gold standard for BRD diagnosis, six reference diagnosis methods were used to define an animal as BRD or non-BRD. Sensitivity (Se) and specificity (Sp) were used to estimate diagnostic accuracy (Acc). Blood metabolomics demonstrated a high accuracy at diagnosing BRD when using visual signs of BRD (Acc = 0.85), however was less accurate at diagnosing BRD using rectal temperature (Acc = 0.65), lung auscultation score (Acc = 0.61) and lung lesions at slaughter as reference diagnosis methods (Acc = 0.71). Phenylalanine, lactate, hydroxybutyrate, tyrosine, citrate and leucine were identified as metabolites of importance in classifying animals as BRD or non-BRD. The blood metabolome classified BRD and non-BRD animals with high accuracy and shows potential for use as a BRD diagnosis tool.

Use of a national identification database to determine the lifetime prognosis in cattle with necrotic laryngitis and the predictive value of venous pCO2

BACKGROUND

Necrotic laryngitis, caused by Fusobacterium necrophorum, frequently requires surgical intervention (laryngostomy) in the chronic stage.

HYPOTHESIS/OBJECTIVES

To determine survival until slaughter of cattle surgically treated for necrotic laryngitis and to identify predictors of mortality.

ANIMALS

A total of 221 cattle diagnosed with necrotic laryngitis by laryngoscopy and surgically treated METHODS: Retrospective cohort study. Clinical records were matched with the national cattle identification, registration, and movement database. Information on possible predictors including clinical examination, biochemistry, and surgery was collected. A multivariable Cox proportional hazard model was used to identify predictors of mortality.

RESULTS

The overall survival rate was 65.2% and 58.6% of the animals with a completed life cycle could be slaughtered. Animals <6 months old experienced significantly higher mortality risk (hazard ratio [HR], 2.0; 95% confidence interval [CI], 1.1-3.5). The venous partial pressure of carbon dioxide (pCO2 ; HR, 2.4; 95% CI, 1.4-4.2) at a 64.5 mm Hg cut-off was most significantly associated with mortality. Sensitivity and specificity of the final model consisting of age and pCO2 were 49.1 and 86.4%, respectively. Instead of pCO2 , total carbon dioxide (TCO2 ) could also be used, with similar diagnostic accuracy.

CONCLUSIONS AND CLINICAL RELEVANCE

The lifetime prognosis for chronic necrotic laryngitis in cattle with surgical intervention appears fair. Age, venous pCO2 and TCO2 are easily accessible predictors of survival to support owners and veterinarians in their decision process of whether or not to operate and to identify high risk animals that require more intensive follow-up.

Evaluating Potential Biomarkers of Health and Performance in Veal Calves

Veal calves undergo many challenges in the early stages of their life. Such challenges, including mixing procedures and transportation of calves to the veal farm, may have a negative influence on growth rate, feed intake, metabolism, immunity and disease susceptibility of calves. As a consequence, many hematological, physiological, metabolic and immunological parameters of stressed calves might be altered on arrival at the veal farm. Some of these response variables might be useful as biomarkers of performance of calves at the veal farm as they might provide information about an ongoing disease process, or may predict future diseases. Biomarkers might be helpful to group and manage calves in different risk categories after arrival. By adopting treatment decisions and protocols on a risk-group or individual basis, it would be possible to improve animal health and reduce both disease incidence and antibiotic use. Moreover, the use of biomarkers might be an economically feasible approach as some of them do not need invasive techniques and others can be measured in blood already taken during routine checks. Previous literature mainly assessed the physiological responses of calves to transportation. However, information on the link between on-farm arrival data and future health and performance of veal calves is limited. This review, therefore, examined a wide range of papers and aimed to identify potential biomarkers of future health and performance.

Prognostic Value of Cardiac Troponin I and L-Lactate in Blood of Dairy Cows Affected by Downer Cow Syndrome

Background

The downer cow syndrome (DCS) is a challenging health issue in the dairy industry. No cow‐side test is available to provide an accurate prognosis for DCS cases in farm settings.

Hypothesis/Objectives

Local or systemic hypoperfusion and myocardial lesions lead to an increase in blood concentration of biomarkers cardiac troponin I (cTnI) and L‐lactate. The objective was to determine the prognostic values of these biomarkers assessed cow‐sides in addition to clinical examinations in prognostication of a negative outcome (NO: death or euthanasia within 7 days).

Animals

218 client‐owned dairy cows affected by DCS.

Methods

In a prospective study, animals were monitored for 60 days after inclusion of each cow. Blood cTnI and L‐lactate concentrations were measured on the day of inclusion. The prognostic accuracy of both biomarkers and physical examination variables was estimated to predict NO. A mixed multivariable logistic regression model was used for data analysis.

Results

Prevalence of NO in this study was 63% on day 7. Troponin concentrations greater than 0.7 ng/mL had sensitivity and specificity of 54.1% (95% CI: 45.3–62.7%) and 78.4% (95% CI: 67.3–87.1%), respectively, for predicting NO. Blood L‐lactate was not associated with the outcome. The multivariable model revealed that heart rate >100 bpm (OR; 95% CI: 3.7; 1.3–10.2) and cTnI > 0.7 ng/mL (OR; 95% CI: 5.5; 2.1–14.6) were associated with the risk of NO.

Conclusions and Clinical Importance

Hypertroponinemia and tachycardia were associated with reduced survival in DCS cases. The use of cow‐side blood cTnI concentrations and heart rate could help to rapidly identify cows in farm setting that have poor chances of recovery and would benefit from a more aggressive treatment or euthanasia.

Preoperative and postoperative L-lactatemia assessment for the prognosis of right abomasal disorders in dairy cattle

BACKGROUND

Preoperative L-lactatemia and heart rate have been suggested as prognostic indicators of outcome for cows with right dilatation of the abomasum or volvulus (RDA/AV). However, postoperative L-lactatemia has not been assessed as a potential prognostic tool.

OBJECTIVES

To determine the prognostic value of postoperative L-lactatemia (LAC2 ), duration of treatment (Dt), relative L-lactatemia difference (compared with preoperative L-lactatemia [LAC1 ]) ([LAC2 - LAC1 ]/LAC2 ) and change in L-lactate over time ([LAC2 - LAC1 ]/Dt) as compared to preoperative findings (LAC1 and heart rate [HR]) as prognostic factors in dairy cows with RDA/AV.

ANIMALS

A total of 41 dairy cows were included: 19 with AV and 22 with RDA; 11 cows had a negative outcome (NO) and 30 cows had a positive outcome (PO) based on telephone follow-up with owners 30 days after surgery.

METHODS

Prospective cohort study. Analysis was performed using logistic regression and comparison of area under the receiver operating characteristics curve (AUC) using nonparametric tests.

RESULTS

LAC1 > 1.4 mmol/L or LAC2 > 2.2 mmol/L had the same accuracy with sensitivity of 100% (95% CI, 75.1-100%) and specificity of 80% (95% CI, 61.4-92.3%) for predicting NO. The relative L-lactatemia difference ([LAC2 - LAC1 ]/LAC1 ) or lactate kinetics ([LAC2 - LAC1 ]/Dt) were not associated with prognosis. The AUC of the preoperative model (which included HR and lnLAC1 ) was 0.92 (95% CI, 0.83-1.0) and that of the postoperative model (including only lnLAC2 ) was 0.95 (95% CI, 0.88-1.0); these were not significantly different.

CONCLUSIONS AND CLINICAL IMPORTANCE

Postoperative L-lactatemia is helpful to predict outcome in cows with RDA/AV. The short-term change in blood L-lactate is not a useful prognostic indicator, at least during the period of time spent on the farm for surgery and treatment.

Animal models of human respiratory syncytial virus disease

Infection with the human pneumovirus pathogen, respiratory syncytial virus (hRSV), causes a wide spectrum of respiratory disease, notably among infants and the elderly. Laboratory animal studies permit detailed experimental modeling of hRSV disease and are therefore indispensable in the search for novel therapies and preventative strategies. Present animal models include several target species for hRSV, including chimpanzees, cattle, sheep, cotton rats, and mice, as well as alternative animal pneumovirus models, such as bovine RSV and pneumonia virus of mice. These diverse animal models reproduce different features of hRSV disease, and their utilization should therefore be based on the scientific hypothesis under investigation. The purpose of this review is to summarize the strengths and limitations of each of these animal models. Our intent is to provide a resource for investigators and an impetus for future research.