Intravenous administration of a polyionic solution containing 84 mEq/l of lactate resolves experimentally induced hyperchloraemic acidosis in horses

Treatment of experimental hyperchloremic metabolic acidosis in horses with enteral electrolyte solution containing sodium acetate

Introduction

In adult horses, the development and evaluation of enteral electrolyte solutions containing sodium acetate for correcting hyperchloremic metabolic acidosis are still lacking, although these electrolyte and acid-base imbalances are commonly observed. The objective of this study was to evaluate the alkalinizing effect of two enteral electrolyte solutions containing different concentrations of acetate, administered via nasogastric tube in continuous flow, in adult horses with experimental hyperchloremic metabolic acidosis.

Methods

Six mares aged between 3 and 10 years were used in a 6×2 crossover design, with each animal receiving both treatments. The horses were subjected to a protocol to induce hyperchloremic metabolic acidosis. They then received one of two treatments: HighAcetate (81.4 mmol/L) and LowAcetate (22.7 mmol/L) at an infusion rate of 15 mL/kg/h for 12 h. Plasma, serum, and urinary biochemical assessments; hematocrit; urinary volume, pH, and specific gravity; and blood gas analysis were measured at the following time points: T-12 h (beginning of the 12-h fast), T0h (end of fasting and beginning of the acidosis induction phase), every 2 h during the hyperchloremic metabolic acidosis induction phase (Ti2h and Ti4h), every 2 h during the 12-h enteral hydration phase (Tt2h, Tt4h, Tt6h, Tt8h, Tt10h, and Tt12h), with one sample taken at T24h (24 h after the start of acidosis induction) and another at T36h (36 h after the start of acidosis induction). Data were analyzed using descriptive statistics and analysis of variance based on a factorial design of repeated measures, with Tukey's post-hoc test or the Kruskal-Wallis test with Dunn's post-hoc test for non-parametric tests.

Results

At the end of the induction phase, the animals developed moderate to severe hyperchloremic metabolic acidosis. The HighAcetate solution effectively corrected electrolyte and acid-base imbalances before the end of the treatment phase (Tt12h), while the LowAcetate solution was not effective in correcting those changes.

Conclusion

The HighAcetate (81.4 mmol/L) solution is deemed an effective and safe alternative for the treatment of hyperchloremic metabolic acidosis in horses.

Current Concepts in Fluid Therapy in Horses

Despite the frequent inclusion of fluid therapy in the treatment of many conditions in horses, there are limited studies available to provide evidenced-based, species-specific recommendations. Thus, equine fluid therapy is based on the application of physiology and extrapolation from evidence in other veterinary species and human medicine. The physiologic principles that underly the use of fluids in medicine are, at first glance, straightforward and simple to understand. However, in the past 20 years, multiple studies in human medicine have shown that creating recommendations based on theory in combination with experimental and/or small clinical studies does not consistently result in best practice. As a result, there are ongoing controversies in human medicine over fluid types, volumes, and routes of administration. For example, the use of 0.9% NaCl as the replacement fluid of choice is being questioned, and the theoretical benefits of colloids have not translated to clinical cases and negative effects are greater than predicted. In this review, the current body of equine research in fluid therapy will be reviewed, connections to the controversies in human medicine and other veterinary species will be explored and, where appropriate, recommendations for fluid therapy in the adult horse will be made based on the available evidence. This review is focused on the decisions surrounding developing a fluid plan involving crystalloids, synthetic colloids, and plasma.

Experimental protocol for metabolic acidosis induction by intravenous administration of hydrochloric acid in sheep

ABSTRACT The aim of this study was to assess the magnitude and duration of blood and urine changes and the side effects of hyperchloremic acidosis induced by the intravenous administration of hydrochloric acid in sheep. Five healthy, crossbred adult ewes, with a mean body weight of 44±2.9kg were used. The hydrochloric acid solution was administered intravenously at a rate of 25mL/kg/h for 4 hours continuously. Venous blood and urine samples were collected and pH values, blood carbon dioxide partial pressure, bicarbonate, base excess, strong ion difference, anion gap, total concentration of nonvolatile buffers, creatinine, plasma L-lactate, plasma and urine sodium, potassium, and chloride were determined. The experimental protocol induced severe hyperchloremic acidosis at the end of the infusion, with a decreased plasma strong ion difference. The fractional excretion of sodium and chloride remained increased during 4 hours after the infusion. Aciduria was observed at approximately 24 hours. Twenty-four hours after the infusion, the animals showed mild and compensated metabolic acidosis. This protocol was effective in inducing severe and long-lasting hyperchloremic acidosis and did not cause serious side effects. Therefore, this protocol can be used safely in adult sheep for studies on the treatment of this condition.

A velocidade de infusão da solução poli-iônica intravenosa contendo 84mEq/L de lactato determina a intensidade do efeito alcalinizante em equinos

RESUMO O objetivo deste trabalho foi verificar os efeitos da solução poli-iônica intravenosa contendo 84mEq/L de lactato (L84) sobre os equilíbrios hidroeletrolítico e ácido-base de equinos, quando administrada de forma rápida ou lenta. Cinco equinos sadios adultos receberam a infusão contínua intravenosa da L84, em volume correspondente a 10% do peso corporal, em duas ocasiões: a) infusão rápida (16,66mL/kg/h) durante seis horas; b) infusão lenta (8,33mL/kg/h) durante 12 horas. Amostras de sangue venoso foram colhidas ao início da infusão (hora zero) e três, seis, nove, 12 e 24 horas após, e amostras de urina nas horas zero, seis, 12 e 24. Determinaram-se pH (sanguíneo e urinário), pCO2, HCO3 -, BE, PPT, lactato L, Na+, K+, Cl-, AG, SID, Atot, VVP, densidade urinária e excreções fracionadas urinárias de lactato L, Na+, K+ e Cl-. A L84 provoca efeito alcalinizante iatrogênico de menor magnitude quando administrada de forma lenta, porque os mecanismos renais, atuantes durante o período de infusão, promovem a correção gradativa do desequilíbrio. Pode-se concluir que a infusão de forma lenta da solução L84 em equinos é recomendável nos casos em que se suspeite de acidose metabólica e não seja possível quantificar o grau do desequilíbrio.