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

To determine the effects of transfusion of Rhodococcus equi hyperimmune plasma (REHIP) on serum electrolyte and protein concentrations in neonatal foals.

A prospective observational study of 355 privately owned Thoroughbred foals from 13 farms in New York and cross-sectional study of REHIP samples. Blood was collected immediately before and after transfusion of either 1 or 2 L of REHIP to foals, and serum samples were separated and frozen until tested for concentrations of sodium (Na), potassium (K), chloride (Cl), total protein (TP), albumin, and globulins. Samples (n = 90) of REHIP were tested for concentrations of Na, K, Cl, TP, albumin, and globulins by the same methodology.

REHIP transfusion resulted in small but significant increases in serum Na, albumin, globulins, and TP concentrations and small but significant decreases in serum Cl and K concentrations. Serum protein concentrations were significantly greater in foals transfused with 2 L than with 1 L. No adverse effects of transfusion were noted in any foals. In REHIP, concentrations of Na were above the serum reference interval.

Magnitudes of changes in serum electrolyte and protein concentrations were small. Although changes were greater for foals transfused with 2 L compared to 1 L, no foals developed marked derangements in measured parameters. Concentrations of measured parameters in REHIP did not vary greatly among manufactured lots or years.

Transfusion of REHIP to foals does not appear to have marked effects on serum concentrations of electrolytes or proteins despite the relatively high Na concentration in REHIP.