LAUSR

&NA; In foals more than 12 hours old, the only effective therapy for the treatment of failure of passive transfer (FPT) of immunity is transfusion of equine plasma. Use and efficacy of equine plasma for prophylaxis and treatment of sepsis, a condition primarily associated with FPT, are widely reported. However, plasma‐ and recipient‐related factors associated with extent of IgG transfer and catabolism are not completely defined. Efficacy and safety of transfusion of a commercial fresh‐frozen hyperimmune plasma were evaluated in hospitalized foals younger than 7 days of age with total or partial FPT. Sixty‐two foals, classified as affected by FPT only, septic (infection plus systemic inflammatory response syndrome [SIRS]), and nonseptic sick, were included, and serum IgG concentration was measured at admission and 24 hours after plasma transfusion. In 25/62 foals, IgG level after 72 hours was also determined. The impact of different classification criteria for septic foals on IgG transfer was evaluated. Serum IgG measured 24 hours and 72 hours after plasma transfusion was significantly greater than at admission, but no significant difference was found in transfer efficacy (TE) between FPT, FPT septic, and FPT nonseptic foals and no significant difference was found in IgG concentration comparing foals with total and partial FPT or survivors and nonsurvivors. No significant difference was found comparing IgG concentration between bacteremic and nonbacteremic foals and foals with or without SIRS. No foal experienced adverse reactions to plasma transfusion. IgG TE and catabolism did not result significantly affected by the presence of sepsis or illness or by the outcome. HighlightsIgG transfer efficacy (TE) of plasma does not differ in failure of passive transfer (FPT) of immunity, septic, and nonseptic foals.IgG is not reduced 72 hours after plasma in FPT, septic, and nonseptic foals.IgG 72 hours after plasma is not different in FPT, septic, and nonseptic foals.Classification criteria for sepsis do not affect IgG TE and catabolism.