Evaluation of glutaraldehyde coagulation test and colostrum BRIX refractometer compared with SNAP foal IgG test in neonatal foals

Abstract

AbstractBackgroundPrompt diagnosis of passive transfer failure in the neonatal period is important for early treatment.ObjectivesTo compare the diagnostic performance of serum glutaraldehyde coagulation test (GCT) and colostrum BRIX% for failure to transfer passive immunity (FTPI) diagnosis with the results of SNAP foal test and to evaluate the results of serum GCT and colostrum BRIX% measurements in foals with diarrhoea in the 0–1 month period.Study designIn vitro experiments.MethodsExcess serum and colostrum (n: 298) from samples collected from newborn foals and their dams for clinical purposes were used. Foals were classified as FTPI positive (IgG < 8 g/L) or negative (IgG ≥ 8 g/L) using the SNAP foal test. We compared the sensitivity and specificity of serum GCT and colostrum BRIX % for diagnosing FTPI in all foals and in the sub‐group of foals which developed diarrhoea within the first month of life was noted. The relationships between the results of the serum GCT and colostrum BRIX% and diarrhoea in foals with and without FTPI were evaluated.ResultsSerum GCT and colostrum BRIX % were statistically significantly different (p < 0.05) between the foals without FTPI and with FTPI classified according to the SNAP test. Using a cut‐off value for serum GCT of >10, sensitivity was 100% (95% CI 92.9%–100%) and specificity 100% (98.3%–100%) while with a cut‐off value of ≤24, with colostrum BRIX% of ≤24 sensitivity was 92% (80.9%–97.8%), and specificity was 98% (95.3–99.3). In the sub‐group of foals without FTPI using a colostrum BRIX% cut‐off value of ≤26 the sensitivity for prediction of diarrhoea in the 0–1 month period was only 72.4% (52.8–87.3, p < 0.001) with specificity 54.3% (47.6–61.1) but the test performance was not robust (ROC AUC 0.61).Main limitationsThe number of repeated measurements in the evaluation of serum GCT, and colostrum BRIX% was low. More clinical problems could be examined.ConclusionsThe serum GCT, and colostrum BRIX%, both economical and practical to use in the field, gave results comparable with the SNAP foal IgG test. The ability to accurately predict diarrhoea in the first month of life with these tests was limited.