Systematic review and meta-analysis of refractometry for diagnosis of inadequate transfer of passive immunity in dairy calves: Quantifying how accuracy varies with threshold using a Bayesian approach.

Inadequate transfer of passive immunity (TPI) is associated with increased risk for calfhood disease and increased risk of mortality and morbidity. Accurately diagnosing calves and herds with inadequate TPI is of primary importance and brix (BRIX) or classical refractometer (REF) devices are more practical for this purpose than measuring the serum immunoglobulin G concentration in neonatal calves. We previously reported a systematic review and meta-analysis for quantifying the pooled accuracy of BRIX and REF for detecting calves with serum IgG < 10 g/L noting that sparse data were available especially because studies did not report the same thresholds. We updated the previous systematic review using different methods that accounted for the test results distribution in calves with or without inadequate TPI. With this approach, all reported cut-offs for a specific study are used in that Bayesian approach that quantifies how accuracy varied among all reported thresholds. Five new manuscripts were included, which represented 4 new studies since the initial study was performed. A total of 11 REF and 9 BRIX studies were available. The meta-analytic methods allowed reporting variation of the true and false positive rate across and among all reported cut-offs. Pooled points estimates (95 % Bayesian credible intervals) for sensitivity (Se) and specificity (Sp) of REF < 5.5 g/L were 86.1 % (68.5-97.9%) and 76.2 % (65.9-88.4%) whereas BRIX < 8.4 % was associated with Se of 91.6 % (77.2-99.5%) and Sp of 88.2 % (65.4-99.8%). Interestingly, the accuracy (Se + Sp-1) was generally higher for BRIX than for REF at the reported cut-offs. Besides the benefit of providing pooled estimates for all reported and unreported BRIX and REF thresholds, the general framework used in this study could potentially be used in many veterinary diagnostic tests studies that reported multiple thresholds accounting for potentially different tests distributions in population with and without the target condition.

Bovine herpes virus type-4 infection among postpartum dairy cows in California: risk factors and phylogenetic analysis.

The aims of this study were to determine the prevalence and associated risk factors of bovine herpes virus type-4 (BoHV-4) infection and describe the genetic characteristics and predominant genotypes of the virus in Yolo and Tulare counties, California. A cross-sectional study involving multi-stage sampling technique was used. One hundred and forty-eight post-partum cows were enrolled from 11 dairy farms. Uterine/vaginal samples were collected and tested for BoHV-4 and other co-infecting viruses using real-time PCR. Data were analysed using multilevel logistic mixed-effect model. Phylogenetic analysis of 10 BoHV-4 isolates was conducted by targeting three open reading frames (ORF3, ORF8 and ORF 22) of the viral genome. The prevalence of BoHV-4 infection was 22.3% (33/148), while post-partum metritis was 33.8% (48/142). Strong association was found between BoHV-4 infection and lactation number, lactation stage and post-partum metritis. The odds of being positive for BoHV-4 infection were 6.47 times (95% CI 1.17-35.92; P 240 days). Cows with post-partum metritis were 4.51 times (95% CI 1.27-16.02; P < 0.05) more likely to test positive for BoHV-4 infection compared with those without post-partum metritis. Phylogenetic analysis of BoHV-4 based on sequencing of glycoprotein and thymidine kinase (TK) genes revealed genetic variability of the virus with glycoprotein B genotype 1 and TK genotype 2 as being dominant genotypes. The reported high genetic variability of BoHV-4 indicates the possibility of co-infection with multiple genotypes.

Systematic Review and Meta-Analysis of Diagnostic Accuracy of Serum Refractometry and Brix Refractometry for the Diagnosis of Inadequate Transfer of Passive Immunity in Calves.

BACKGROUND: Transfer of passive immunity in calves can be assessed by direct measurement of immunoglobulin G (IgG) by methods such as radial immunodiffusion (RID) or turbidimetric immunoassay (TIA). IgG can also be measured indirectly by methods such as serum refractometry (REF) or Brix refractometry (BRIX). OBJECTIVES: To determine the accuracy of REF and BRIX for assessment of inadequate transfer of passive immunity (ITPI) in calves. DESIGN: Systematic review and meta-analysis of diagnostic accuracy studies. METHODS: Databases (PubMed and CAB Abstract, Searchable Proceedings of Animal Science) and Google Scholar were searched for relevant studies. Studies were eligible if the accuracy (sensitivity and specificity) of REF or BRIX was determined using direct measurement of IgG by RID or turbidimetry as the reference standard. The study population included calves <14 days old that were fed with natural colostrum (colostrum replacement products were excluded). Quality assessment was performed by the QUADAS-2 tool. Hierarchical models were used for meta-analysis. RESULTS: From 1,291 references identified, 13 studies of 3,788 calves were included. Of these, 11 studies evaluated REF and 5 studies evaluated BRIX. The median (range) prevalence of ITPI (defined as calves with IgG <10 g/L by RID or TIA) was 21% (1.3-56%). Risk of bias and applicability concerns were generally low or unclear. For REF, summary estimates were obtained for 2 different cutoffs: 5.2 g/dL (6 studies) and 5.5 g/dL (5 studies). For the 5.2 g/dL cutoff, the summary sensitivity (95% CI) and specificity (95% CI) were 76.1% (63.8-85.2%) and 89.3% (82.3-93.7%), and 88.2% (80.2-93.3%) and 77.9% (74.5-81.0%) for the 5.5 g/dL cutoff. Due to the low number of studies using the same cutoffs, summary estimates could not be obtained for BRIX. CONCLUSIONS AND CLINICAL IMPORTANCE: Despite their widespread use on dairy farms, evidence about the optimal strategy for using refractometry, including the optimal cutoff, are sparse (especially for BRIX). When using REF to rule out ITPI in herds, the 5.5 g/dL cutoff may be used whereas for ruling in ITPI, the 5.2 g/dL cutoff may be used.

Seizure Disorders in Goats and Sheep.

BACKGROUND: Goats and sheep are more likely to be presented for examination for seizures than are cattle, possibly as a consequence of their relatively smaller body size. Currently, no reports describing seizure disorders in goats and sheep are available. OBJECTIVES: To describe clinical features and treatment outcomes of sheep and goats presented for seizures. ANIMALS: A total of 59 goats and 21 sheep presented for seizures. METHODS: Retrospective study. Medical records from 1994 to 2014 at the Veterinary Medical Teaching Hospital, University of California, Davis, were reviewed. Descriptive statistics were used to summarize data. Logistic regression was performed to determine whether variables were associated with mortality. RESULTS: The majority of seizures in goats and sheep had structural or metabolic causes. Polioencephalomalacia (PEM) secondary to ruminal lactic acidosis or PEM of undetermined cause was the most frequently diagnosed cause of seizures in goats and sheep. The proportions of mortality in goats and sheep were 49.2 and 42.9%, respectively. Age increased the odds mortality (odds ratio [OR], 1.51; 95% confidence interval [CI], 1.07, 2.14) in goats. Goats with structural or metabolic causes of seizures had higher odds for mortality (OR, 37.48; 95% CI, 1.12, 99.10) than those with unknown causes. Age and etiological diagnosis were not significant (P > .05) predictors of mortality in affected sheep. CONCLUSIONS AND CLINICAL RELEVANCE: Seizure disorders in goats and sheep are associated with high mortality, despite treatment. Current treatment in goats and sheep with seizures warrants further investigation to determine whether treatments are beneficial or detrimental to survival.

Diagnostic accuracy of refractometer and Brix refractometer to assess failure of passive transfer in calves: protocol for a systematic review and meta-analysis.

Calves are highly dependent of colostrum (and antibody) intake because they are born agammaglobulinemic. The transfer of passive immunity in calves can be assessed directly by dosing immunoglobulin G (IgG) or by refractometry or Brix refractometry. The latter are easier to perform routinely in the field. This paper presents a protocol for a systematic review meta-analysis to assess the diagnostic accuracy of refractometry or Brix refractometry versus dosage of IgG as a reference standard test. With this review protocol we aim to be able to report refractometer and Brix refractometer accuracy in terms of sensitivity and specificity as well as to quantify the impact of any study characteristic on test accuracy.

A randomized clinical trial evaluating metabolism of colostral and plasma derived immunoglobulin G in Jersey bull calves.

BACKGROUND: Intravenous plasma administration has been recommended in healthy or sick calves with failure of passive immunity. HYPOTHESIS: IV administered plasma-derived immunoglobulin G (IgG) undergoes increased catabolism as reflected by a rapid decrease in serum IgG concentration with an increase in fecal IgG concentrations within 48 h. ANIMALS: Thirty newborn Jersey calves. Fifteen were fed colostrum (CL group) and 15 were given bovine plasma IV (PL group). MATERIALS AND METHODS: Randomized clinical trial. Calves in the CL group were fed 3 L of colostrum once, by oroesophageal tubing. Calves in the PL group were given plasma IV at a dosage of 34 mL/kg. Serum and fecal samples were collected at 0 h, 6 h, 12 h, 48 h, 5 d, and 7 d. Serum and fecal IgG concentrations were determined by radial immunodiffusion. RESULTS: Calves in the CL group maintained serum IgG concentrations consistent with adequate transfer of immunity (≥1,000 mg/dL) throughout the study period. Calves in the PL group achieved median IgG concentrations of ≥1,000 mg/dL at 6 h but the concentrations were <1,000 mg/dL by 12 h. Calves in the PL group were 5 times more likely to experience mortality compared to the CL group (hazard ratio = 5.01). Fecal IgG concentrations were not different between the 2 groups during the first 48 h (P > .05). CONCLUSIONS AND CLINICAL IMPORTANCE: Catabolism of plasma derived IgG occurs rapidly during the first 12 h after transfusion. Fecal excretion did not explain the fate of the plasma derived IgG.

Preliminary investigation of cardiac troponin I concentration in cows with common production diseases.

BACKGROUND: Increased cTnI concentrations are associated with adverse outcomes in humans and animals. Limited information is available on the prognostic value of cTnI in cows. OBJECTIVE: To measure cTnI in cows with noncardiac diseases and evaluate the association of cTnI concentration with adverse outcomes such as death or early removal from the herd. ANIMALS: Thirty control and 53 diseased cows. METHODS: Serum cTnI concentrations were determined with a point-of-care immunoassay. Cows were diagnosed ante- or postmortem with metritis (n = 6), mastitis (n = 4), peritonitis (n = 6), LDA (n = 14), LDA and metritis (n = 4), pneumonia (n = 6), dystocia requiring cesarean section (n = 5), and downer cow syndrome (n = 8). Animal survival was determined for up to 2 months after presentation. RESULTS: The immunoassay showed reliability for the detection of bovine cTnI. Cows with LDA and metritis (P < .05), peritonitis (P < .05), LDA (P < .001), dystocia requiring cesarean section (P < .01), and downer cow syndrome (P < .001) had higher cTnI concentrations than control cows. The odds of a negative outcome (death or culling) for cows with cTnI concentrations of ≥ 0.05, ≥ 0.1, ≥ 0.2, and ≥ 0.5 ng/mL were 2.4, 2.9, 4.8, and 6.2, respectively. CONCLUSION: Cows with noncardiac diseases may have some degree of myocardial injury. The magnitude of cTnI increased may assist clinicians in evaluating the risk of an adverse outcome and help guide decision-making regarding treatment and prognosis.

Serum IgG concentrations after intravenous serum transfusion in a randomized clinical trial in dairy calves with inadequate transfer of colostral immunoglobulins.

BACKGROUND: Plasma transfusions have been used clinically in the management of neonates with failure of passive transfer. No studies have evaluated the effect of IV serum transfusions on serum IgG concentrations in dairy calves with inadequate transfer of passive immunity. HYPOTHESIS: A commercially available serum product will increase serum immunoglobulin concentration in calves with inadequate transfer of colostral immunoglobulins. ANIMALS: Thirty-two Jersey and Jersey-Holstein cross calves with inadequate colostral transfer ofimmunoglobulins (serum total protein < 5.0 g/L). METHODS: Thirty-two calves were randomly assigned to either control (n = 15) or treated (n = 17) groups. Treated calves received 0.5 L of a pooled serum product IV. Serum IgG concentrations before and after serum transfusion were determined by radial immunodiffusion. RESULTS: Serum protein concentrations increased from time 0 to 72 hours in both control and transfused calves and the difference was significant between the control and treatment groups (P < .001). Mean pre- and posttreatment serum IgG concentrations in control and transfused calves did not differ significantly. Median serum IgG concentrations decreased from 0 to 72 hours by 70 mg/dL in control calves and increased over the same time interval in transfused calves by 210 mg/dL. The difference was significant between groups (P < .001). The percentage of calves that had failure of immunoglobulin transfer 72 hours after serum transfusion was 82.4%. CONCLUSIONS AND CLINICAL IMPORTANCE: Serum administration at the dosage reported did not provide adequate serum IgG concentrations in neonatal calves with inadequate transfer of colostral immunoglobulins.