Evaluation of five commercially available assays and measurement of serum total protein concentration via refractometry for the diagnosis of failure of passive transfer of immunity in foals.

This study looks at the effectiveness of different tests in diagnosing if foal horses have failed to receive enough immunity (antibodies) from their mothers. It establishes that most of these commercial tests can be valuable as initial screening tools, but their usage as definitive tests can result in unnecessary treatments.

Research Overview

The primary purpose of this study, as demonstrated in the article, is to evaluate the sensitivity, specificity, accuracy, and predictive abilities of different diagnostic methods in assessing the failure of passive transfer (FPT) of immunity in foals. The FPT refers to the inadequate absorption of IgG (Immunoglobulin G) antibodies from their mother’s colostrum, which can lead to increased susceptibility to infections.

The research has a dual emphasis:

• It aims to check and compare the performance of the five commercially available assays, each testing for serum IgG concentrations.
• It further aims to measure the serum total protein concentration using refractometry.

Research Methods

The researchers used a sample size of 65 foals with various medical problems and 35 clinically healthy foals to conduct their study. Different tests were used to assess IgG concentrations, including zinc sulfate turbidity, glutaraldehyde coagulation, two semi-quantitative immunoassays, and a quantitative immunoassay for the other assay. Serum total protein concentration was assessed using refractometry.

Research Results

The findings indicated that for detecting IgG lower than 400 mg/dL, the sensitivity of the quantitative immunoassay was not significantly different from other assays. In terms of specificity, the performance of this assay and the semi-quantitative immunoassay was significantly higher than other tests.

When detecting IgG that’s less than 800 mg/dL, the sensitivity of several assays was significantly higher than another semi-quantitative immunoassay. The specificity of all tests except the zinc sulfate turbidity and glutaraldehyde coagulation assays was significantly higher.

Based on the results, serum total protein concentration less than or equal to 4.5 g/dL was suggestive of FPT, while values greater or equal to 6.0 g/dL showed adequate IgG concentrations.

Research Conclusions

The study concluded that most currently available assays can serve as effective initial screening tests for FPT in foals. However, the results also imply that using these tests as the final diagnostic tool might lead to unnecessary treatment, since foals with sufficient IgG concentrations may still test positive.