Acta Vet. Brno 2020, 89: 225-230

Comparison of plasma and intra-articular gentamicin levels after intravenous administration in healthy horses

Marília Alves Ferreira, Mayra Lissoni Aguiar, Renan Grigoletto, Danielle Passarelli, Julia de Assis Arantes, Gustavo Morandini Reginato, Pedro Henrique Salles Brito, Thiago Jonatha Fernandes da Silva, Renata Gebara Sampaio Dória

University of Sao Paulo (USP), Faculty of Animal Science and Food Engineering (FZEA), Pirassununga, São Paulo, Brazil

Received June 10, 2019
Accepted June 22, 2020

Septic arthritis is considered one of the most severe disorders that affect horses’ joints. Therapy is intended to eliminate the microorganisms that cause this infection. The intravenous administration of antibiotics is an easily performed technique, but there is no guarantee that the antibiotics will reach the joint milieu at high concentrations and remain elevated for a certain period of time. This study aimed to determine and compare the levels of gentamicin in the plasma and synovial fluid of healthy horses after intravenous administration for seven days. Five horses received 6.6 mg/kg intravenous gentamicin every 24 h for seven consecutive days. Blood and synovial fluid samples were collected from the right metacarpal-phalangeal joint before the start of the treatment (T0) and after 6 h (T6), 12 h (T12), and every 24 h during antibiotic therapy for seven days (D1 to D7). The levels of gentamicin in serum and synovial fluid were quantified by Enzyme-Linked Immunosorbent Assay (ELISA). The intravenous administration of 6.6 mg/kg of gentamicin, in horses, after a period of 24 h, promotes synovial fluid concentrations below the MIC of the drug, in spite of reaching high plasma concentrations of gentamicin, daily mean serum concentration which was 29-fold higher than the minimum inhibitory concentration (MIC) of the drug. The intravenous administration every 24 h during seven consecutive days did not cause systemic side effects, such as hepatic or renal injury.


The authors acknowledge the financial support from Fundação de Amparo à Pesquisa do Estado de São Paulo (Fapesp - process no. 2013/20662-8 and 2019/03193-0) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq - process no. 449297/2014-4).


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