Comparison of IgG concentrations by radial immunodiffusion, electrophoretic gamma globulin concentrations and total globulins in neonatal foals.

This study investigates the comparison of three diagnostic methods that measure immunity levels in newborn foals. Results indicate that electrophoretic gamma globulins (EGG) and radial immunodiffusion (IgG-RID) show strong agreement, albeit with EGG estimates being slightly more conservative. The study also suggests that total globulin measurements could offer an economically feasible screening method for detecting failure of passive immunity transfer in foals, although specific cut-off points may vary based on the testing device used.

Research Objectives and Methods

• The main goal of this prospective study was to evaluate the relationship between EGG and IgG-RID and to assess how well total globulin concentration can diagnose Failure of Transfer of Passive Immunity (FTPI) compared against both EGG and IgG-RID.
• 360 serum samples were taken from 60 German Warmblood foals at 6-24 hours after birth. Concentrations of EGG, IgG-RID, and total globulin were measured.
• The study used different analysis tools, including Bland-Altman plots, Passing-Bablok regression, rank correlation, and ROC curve analysis to assess agreement, accuracy, and correlations.

Research Findings

• There was a good agreement between the EGG and IgG-RID measurements. However, EGG measurements were slightly lower than the IgG-RID readings with a nominal systemic bias of -1.9 g/l.
• This difference was more emphatic at higher concentration levels.
• Correlations between total globulin concentration and both the EGG and IgG-RID measurements were strong, at 0.93 and 0.79 respectively.
• The area under the curve (indicating test accuracy) for both EGG and IgG-RID was high, ranging between 0.899 (for IgG-RID <8 g/l) and 0.982 (for EGG <4 g/l).
• Applying total globulin concentration in diagnosing FTPI delivered sensitivity and specificity performance on par with commonly used screening tests.

Conclusions and Recommendations

• The findings indicate a strong agreement between EGG and IgG-RID measurements, with EGG providing slightly more conservative estimates of immunoglobulins.
• Total globulin concentration could serve as an efficient and economical quantitative screening test. Its high sensitivity makes it a potential tool for detecting FTPI in foals.
• However, the exact cut-offs for diagnosing FTPI using total globulin concentration might need to be tailored to the specific analyzer used.