Evaluation of IgG concentration and IgG subisotypes in foals with complete or partial failure of passive transfer after administration of intravenous serum or plasma.

The research focuses on examining the effectiveness of equine plasma and concentrated serum products in delivering antibodies to foals (young horses) suffering from a failure of passive transfer (FPT). The study finds that while both products can deliver antibodies, plasma treatment resulted in a stronger increase in antibody concentration due to its higher IgG content.

Objective and Procedure

• The main purpose of the study was to evaluate the capacity of an equine plasma product and a concentrated serum product to deliver antibodies to 46 foals diagnosed with failure of passive transfer (FPT). This condition refers to a foal’s inability to acquire necessary immunity components from its mother’s milk, leaving it vulnerable to various infectious agents.
• Both plasma and concentrated serum products were administered intravenously as per the recommendations of the respective manufacturers. The quantity used was 950 ml/unit for the plasma product and 250 ml/unit for the serum product.

Variables and Results

• Significant variables affecting the serum immunoglobulin G (IgG) concentration of foals three days post-transfusion included factors such as the body weight of the foal, the IgG concentration before transfusion, the number of product units transfused, the season during which foaling occurred, and the actual product administered. Immunoglobulin G (IgG) is the most common type of antibody found in blood circulation, they are critical for fighting bacterial and viral infections.
• The study observed a higher increase in IgG concentrations post-transfusion in foals treated with plasma, as compared to those treated with the serum product. The plasma product contained approximately double the amount of IgG per unit relative to the serum product.

Measurement of Specific Antibodies

• The researchers also measured the change in the titres of foal antibodies specific to equine influenza virus and tetanus toxoid, from before the transfusion to three days after the transfusion.
• These measurements accounted for variations in IgGa, IgGb, and IgG(T) subisotypes. Subisotypes are different forms of an antibody that are produced by different classes of plasma cells and have different functions.
• The changes in subisotype levels for each gram of IgG transfused were observed to be similar across both treatment groups.

Conclusions of the Study

• Concluding the study, the researchers suggest similar foal serum IgG concentrations could be achieved three days post-transfusion by administering one unit of plasma or two to three units of serum product.
• The choice between equine plasma and concentrated serum products might therefore depend on other factors, such as the specific requirements of the foal or the cost and availability of the products.