Plasma and peritoneal fluid concentrations of ceftriaxone after intravenous and intraperitoneal administration in horses

Plasma and Peritoneal Ceftriaxone Concentrations After Intraperitoneal Administration in Horses With Septic Peritonitis

Intraperitoneal ceftriaxone administration in healthy horses results in high and prolonged peritoneal concentrations. Recent findings suggest that intraperitoneal ceftriaxone might increase survival rates in horses affected by peritonitis. The present study aimed to evaluate plasma and peritoneal concentrations of ceftriaxone after intraperitoneal administration in horses with septic peritonitis. Twenty-six horses presenting clinical, laboratorial, and sonographic findings compatible with the disease were included. All horses received daily intraperitoneal ceftriaxone (25 mg/kg bwt) in addition or not with other antibiotics and support therapies. High-performance liquid chromatography was used to determine plasma and peritoneal ceftriaxone concentrations before and after 12 and 24 hours of ceftriaxone administration. Mean plasma concentrations 12 and 24 hours after administration were, respectively, 1.84 ± 0.43 and 0.37 ± 0.07 μg/mL, and mean peritoneal concentrations were 5.7 ± 2.84 and 0.42 ± 0.13 μg/mL. Ceftriaxone concentration was lower in comparison with previous studies in healthy horses and presented under the minimal inhibitory concentration for enterobacteria (≤1 μg/mL) and for gram-positive isolates (≤0.5 μg/mL) at 24 hours. The variation of the results obtained between healthy horses and with septic peritonitis demonstrated that pharmacokinetics/dynamics are different between these patients and suggests the use of an interval of dose of 12 hours.

The equine mononuclear phagocyte system: The relevance of the horse as a model for understanding human innate immunity

The mononuclear phagocyte system (MPS) is a family of cells of related function that includes bone marrow progenitors, blood monocytes and resident tissue macrophages. Macrophages are effector cells in both innate and acquired immunity. They are a major resident cell population in every organ and their numbers increase in response to proinflammatory stimuli. Their function is highly regulated by a wide range of agonists, including lymphokines, cytokines and products of microorganisms. Macrophage biology has been studied most extensively in mice, yet direct comparisons of rodent and human macrophages have revealed many functional differences. In this review, we provide an overview of the equine MPS, describing the variation in the function and phenotype of macrophages depending on their location and the similarities and differences between the rodent, human and equine immune response. We discuss the use of the horse as a large animal model in which to study macrophage biology and pathological processes shared with humans. Finally, following the recent update to the horse genome, facilitating further comparative analysis of regulated gene expression between the species, we highlight the importance of future transcriptomic macrophage studies in the horse, the findings of which may also be applicable to human as well as veterinary research.

Adjuvant intraperitoneal ceftriaxone in the treatment of septic peritonitis in horses

BACKGROUND

Intraperitoneal administration of ceftriaxone maintains therapeutic abdominal concentrations for 24 hours in healthy horses. Therefore, it is a possible treatment for septic peritonitis. The aim of this study was to evaluate the efficacy of ceftriaxone as an adjuvant treatment in horses with septic peritonitis.

METHODS

Twenty-six horses with clinical signs, sonography and/or laboratory findings of septic peritonitis were included. Peritoneal fluid was collected for microbiological culture and in vitro microbial sensitivity profile assessment. Daily intraperitoneal administration of ceftriaxone (25 mg/kg) was initiated with supportive and systemic antimicrobial treatment. The animals were divided into three groups: group 1-gastrointestinal tract injuries and abdominal surgery (excluding perforations/ruptures); group 2-not related to changes in the gastrointestinal tract; group 3-secondary to intestinal rupture and/or faeces contamination.

RESULTS

The mean success rate of the treatment was 77 per cent (20/26 animals), with success rates of 84.6 per cent in group 1; 87.5 per cent, group 2; and 40 per cent, group 3.

CONCLUSIONS

This is the first study to report adjuvant intraperitoneal treatment ceftriaxone for septic peritonitis in horses and indicates that this treatment can successfully treat septic peritonitis in horses.