Serum Electrolyte Changes in Foals Receiving Rhodococcus equi-Specific Hyperimmune Plasma

Rhodococcus equi-specific hyperimmune plasma (Re-HIP) is routinely administered to neonatal foals to help prevent rhodococcal pneumonia. In addition to pathogen-specific immunoglobulins, frozen plasma products (FPPs) contain electrolytes that may exceed concentrations found in neonatal foal plasma. Because FPPs are also used to treat failure of passive transfer and sepsis, understanding their effects on neonate homeostasis is crucial. This study evaluated the effects of administration of Re-HIP on the serum concentrations of Na⁺, Cl^-, K⁺, albumin, and globulin of healthy neonatal foals.

The concentration of Na⁺ was high in Re-HIP when compared with normal plasma values. Administration of Re-HIP resulted in an increase in serum Na⁺, Cl^-, albumin, and globulin concentrations in neonatal foals.

The serum electrolyte changes seen after Re-HIP administration were likely of no clinical significance in healthy foals. However, the administration of hypernatremic plasma to septic or dehydrated foals could exacerbate electrolyte imbalances. These results suggest that caution and close monitoring are warranted when administering FPPs to critically ill foals.