Preoperative cow-side lactatemia measurement predicts negative outcome in Holstein dairy cattle with right abomasal disorders
ABSTRACT The objectives of the current study were (1) to determine the gain in prognostic accuracy of preoperative l-lactate concentration (LAC) measured on farm on cows with right displaced abomasum (RDA) or abomasal volvulus (AV) for predicting negative outcome; and (2) to suggest clinically relevant thresholds for such use. A cohort of 102 cows with on-farm surgical diagnostic of RDA or AV was obtained from June 2009 through December 2011. Blood was drawn from coccygeal vessels before surgery and plasma LAC was immediately measured by using a portable clinical analyzer. Dairy producers were interviewed by phone 30 d following surgery and the outcome was determined: a positive outcome if the owner was satisfied of the overall evolution 30 d postoperatively, and a negative outcome if the cow was culled, died, or if the owner reported being unsatisfied 30 d postoperatively. The area under the curve of the receiver operating characteristic curve for LAC was 0.92 and was significantly greater than the area under the curve of the receiver operating characteristic curve of heart rate (HR; 0.77), indicating that LAC, in general, performed better than HR to predict a negative outcome. Furthermore, the ability to predict a negative outcome was significantly improved when LAC measurement was considered in addition to the already available HR data (area under the curve: 0.93 and 95% confidence interval: 0.87, 0.99). Important inflection points of the misclassification cost term function were noted at thresholds of 2 and 6 mmol/L, suggesting the potential utility of these cut-points. The 2 and 6 mmol/L thresholds had a sensitivity, specificity, positive predictive value, and negative predictive value for predicting a negative outcome of 76.2, 82.7, 53.3, and 93.1%, and of 28.6, 97.5, 75, and 84%, respectively. In terms of clinical interpretation, LAC ≤2 mmol/L appeared to be a good indicator of positive outcome and could be used to support a surgical treatment decision. The treatment decision for cows with LAC between 2 and 6 mmol/L, however, would depend on the economic context and the owner's attitude to risk in regard to potential return on its investment. Finally, performing a surgical correction on commercial cows with RDA or AV and a LAC ≥6 mmol/L appeared to be unjustified and these animals should be culled based on their high probability of negative outcome.
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ABSTRACT: The bovine respiratory disease complex (BRD) is a major health issue in feedlot cattle and one of the primary reasons for antimicrobial use in the North American feedlot industry. The purpose of the present study was to assess blood l-lactate levels of feedlot steers at high risk of developing BRD during the early feeding period. Blood samples were obtained at initial processing and again after BRD confirmation (using bronchial lavage or thoracic ultrasound exam). The study involved 232 recently weaned steers received at a single research feedlot that were processed without metaphylactic antimicrobial treatment. Blood samples were obtained for determination of l-lactatemia and temperament scores (very quiet or stoic [score 1], average [score 2] and very excited [score 3]) were systematically assigned at initial processing. A subsample of calves that were later confirmed as cases of BRD were sampled at first pull (day 0), and at subsequent observation points on days 3, 6, 9 and 15 following initial BRD diagnosis for blood lactate determination as a potential indicator of subsequent death. The clinical BRD cumulative incidence in the cohort was 38% (87/232). Temperament was associated with the probability of becoming a BRD case during the early feeding period. Stoic or very excited calves showed 2.2 times higher odds (95%CI: 1.3, 3.8) of becoming BRD cases compared to calves with average temperament. The impact of l-lactatemia differed by temperament strata. In calves with a temperament score of 2 (average temperament) every 1-log unit increase of lactatemia at processing resulted in 1.9 times higher odds (95% CI: 1.2, 3.1) of becoming a BRD case; this relationship was not significant in calves with a score of either 1 or 3. Twenty-nine confirmed BRD cases were studied for the dynamic lactate assessment analysis. l-lactate at first pull was not significantly different between survivors (median 3.3 mmol/L; range 0.8–7.8 mmol/L) and non-survivors (median 2.7 mmol/L; range: 1.6–5.4 mmol/L) steers. However, the dynamic assessment of l-lactatemia was associated with the hazard of death using Cox proportional hazard survival analysis. A 1-log increase of lactatemia increased the hazard of dying prior to the next observation by a factor of 36.5 (95% CI: 3.5–381.6).Preventive Veterinary Medicine 12/2014; 118(4). DOI:10.1016/j.prevetmed.2014.12.003 · 2.51 Impact Factor
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ABSTRACT: Background Blood L-lactate concentration (LAC) can be used for various diagnostic purposes in cattle. As multiple handheld analyzers for LAC exist, it is important to validate their use in cattle in comparison with reference laboratory blood analyzers.Objectives The objectives of this study were to validate the handheld Lactate Pro meter (LacP) including reproducibility, and compare the measurements with the StatProfile (StatP) as a gold standard. In addition, diagnostic sensitivity and specificity, and the impact of HCT on LAC measured by both analyzers were assessed.MethodsA cohort of 64 cattle with acute medical and surgical conditions was studied. Whole blood samples in heparin lithium tubes were analyzed upon arrival with both StatP and LacP. Twenty-three samples were immediately retested to assess intra-assay coefficient of variation (CV). The HCT values were also recorded.ResultsThe LAC using LacP was highly correlated with the StatP (r = 0.9736 [95% confidence interval [CI]: 0.9562–0.9841]). The LacP underestimated LAC (mean difference:−0.9 mmol/L, 95% CI:−3.1 mmol/L to 1.3 mmol/L). The intra-assay CV was excellent (4.77%). No significant correlation was observed between LacP or StatP and HCT (P = .39 and .09, respectively). Sensitivity and specificity for LacP were 91.7% (95% CI: 76.4–97.8%) and 100% (83.4–100%, cutoff of 4 mmol/L), and 78.6% (58.5–90.9%) and 100% (87.0–100%, cutoff of 6 mmol/L).Conclusions The LacP handheld lactate meter can be used safely and reliably cow-side, although it underestimates LAC value when compared with a standard laboratory analyzer especially for LAC ≥ 10.0 mmol/L. The LAC value was not influenced by HCT in this study.Veterinary Clinical Pathology 08/2014; DOI:10.1111/vcp.12185 · 1.21 Impact Factor