Transfusion of rhodococcal hyperimmune plasma to newborn foals does not markedly alter serum electrolyte or protein concentrations.

Overview

• This study examined whether transfusing Rhodococcus equi hyperimmune plasma (REHIP) into newborn foals causes significant changes in their blood electrolyte and protein levels.
• The findings indicate that while there are small changes in certain serum electrolytes and proteins after transfusion, these changes are not substantial or harmful to the foals.

Background and Objective

• Rhodococcus equi is a bacterial pathogen that can cause severe pneumonia in foals; hyperimmune plasma developed against this bacterium is often transfused to enhance immunity in young foals.
• The goal of this research was to determine if transfusing REHIP alters serum electrolyte (sodium, potassium, chloride) and protein (total protein, albumin, globulins) concentrations in newborn foals.
• This is important because transfusions might potentially affect blood chemistry and cause health issues if the plasma composition is too different from normal foal serum.

Study Design and Methods

• A prospective observational study was conducted on 355 Thoroughbred foals from 13 farms in New York.
• Foals received transfusions of 1 or 2 liters of REHIP, selected without specific assignment to volume groups.
• Blood samples from each foal were collected immediately before and immediately after transfusion to measure serum levels of sodium (Na), potassium (K), chloride (Cl), total protein (TP), albumin, and globulins.
• Additionally, 90 samples of the REHIP itself were analyzed for the same components to ascertain their makeup and consistency across different manufacturing lots and years.
• The analysis was standardized using the same methodology for both foal serum and REHIP samples to ensure accurate comparisons.

Key Findings

• Transfusion of REHIP caused statistically significant but small increases in serum sodium, albumin, globulin, and total protein concentrations in the foals.
• Conversely, small but significant decreases were observed in serum chloride and potassium concentrations post-transfusion.
• Foals receiving 2 liters of plasma showed greater increases in serum protein concentrations than foals receiving 1 liter, indicating a dose-dependent effect.
• Despite these changes, no foals displayed adverse effects related to electrolyte or protein imbalances after transfusion.
• Analysis of the REHIP samples revealed consistently elevated sodium levels compared to typical serum reference intervals, but these elevated sodium levels did not result in marked hypernatremia after transfusion.
• The measured serum components in REHIP did not vary substantially across different production batches or years, indicating reliable plasma composition.

Interpretation and Conclusions

• The small magnitude of changes in electrolytes and proteins suggests that REHIP transfusion is safe and does not cause significant biochemical disturbances in neonatal foals.
• The higher sodium concentration in REHIP does not translate into clinically relevant alterations in the foals’ serum sodium levels, possibly due to homeostatic regulation.
• The volume of transfusion (1 vs. 2 liters) has a measurable effect on serum protein concentrations, but even larger transfusions did not provoke harmful imbalances.
• These findings support the continued use of REHIP as a prophylactic or therapeutic plasma transfusion in foals without concern for major electrolyte or protein disturbances.

Implications for Veterinary Practice

• Veterinarians can be reassured that transfusing REHIP to newborn foals is unlikely to cause significant shifts in serum electrolytes or proteins that could compromise foal health.
• Monitoring of serum chemistries immediately before and after REHIP transfusions may still be advisable, but routine adverse effects related to electrolyte or protein imbalances are unlikely.
• Using either 1 or 2 liters of REHIP can be considered safe based on the data from this large population of Thoroughbred foals.