Clinical use of a commercial hyperimmune plasma in hospitalized foals with FPT

Aim of the study: The purpose of this study was to evaluate the efficacy and safety of the administration of a commercial hyperimmune plasma in septic and non-septic foals with failure of passive transfer (FPT). Materials and methods: Fifty-two hospitalized foals <7 day-old admitted with FPT were included and all treated with hyperimmune plasma infusion. A complete clinical examination was performed upon admission, including blood count and biochemical exam, the determination of the IgG (if the foal was at least 18 hours old), and blood culture. Foals with a positive blood culture were classified as septic (25/52). Complete FPT was defined as a serum IgG concentration <400 mg/dL and partial FPT between 400 and 800 mg/dL at 24 hours of life [1]. Serum IgG concentration was measured before (IgG0) and 24 hours after the end of plasma administration (IgGp) [2], using an immunoturbidimetric method (DVM Rapid TestTM - Value Diagnostics, USA) [3]. For foals that had not ingested colostrum before admission the serum IgG concentration was considered to be equal to 0. PlasmaLife® (Società Il Ceppo, Siena, Italy), was administered to all foals according to the literature guidelines for the administration of hyperimmune equine plasma [1]. The occurrence of any adverse reactions by the foals was monitored throughout the hospitalization period. The following data were collected: IgG0, IgGp, volume of plasma administered, increase in IgG (ΔIgG), IgG transfer efficacy (TE), blood culture, diagnosis, and outcome. The TE was calculated for each foal by the formula ΔIgG/Lplasma/kg of body weight. ΔIgG is the difference between IgGp and IgG0. The Wilcoxon test was used to evaluate the ΔIgG. The Mann-Whitney test was used to evaluate the difference (p<0,05) in TE between septic and non-septic foals. Results: Twenty-nine/52 foals (56%) had complete FPT and 23/52 (44%) had partial FPT. The mean value of IgG0 was 375 ±279 mg/dL. Of the 52 foals, 25 were classified as septic, and the remaining 27 as non-septic. The mean volume of PlasmaLife® administered was 1.3 ±0.5 L, therefore 1.3 ±0.6 units of plasma. The mean value of IgGp was 1025 ±410 mg/dL. Considering all of the foals, the mean ΔIgG was 650 ±439 mg/dL and the mean TE was 13 ± 11 mg/dL/L/kg . In the 25 septicemic foals, the mean ΔIgG was 603 ±692mg/dL and the mean TE was 11 ±8 mg/dL/L/kg; in the 27 non-septicemic foals ΔIgG was 694 ±481mg/dL and the mean TE was 15 ±13mg/dL/L/kg. According to PlasmaLife® characteristics, a minimum quantity of IgG content equal to 2400 mg/dL, should lead to an increase of serum IgG of 400-800 mg/dL in non-septic foal [1]. TE fell within a very wide range, which may depend on various factors, like a state of septicemia or a difference between partial or complete FPT [4]. IgGp was significantly higher than IgG0 (p <0.05). No significant difference was found in TE among the group of septic foals and non-septic foals. Althought not statistically different in our study, TE in septic foals was less than that in non-septic foals. Independently of the presence of septicemia, the seriousness of the disease itself may also influence IgG catabolism. None of the 52 foal included in our study experienced adverse reactions during or after the plasma administration, despite the transfusion reaction incidence of 9.7% reported by other authors in foals <7 day-old [5]. This may be at least partially related to PlasmaLife® charateristics, as it’s produced using a 0.2 µm plasma filter followed by sterilizing filtration at 0.1 µm and thus doesn’t contain blood corpuscular elements, which most frequently cause adverse reactions [16]. 34/52 foals survived, so the percentage of survival was 65% (also considering as non surviving the foals euthanized for compassionate reasons). Conclusions: The results of the study clearly show that the administration of PlasmaLife® was effective and safe in correcting FPT in foals included in this study.