Intravenous Application of Metronidazole, Ceftriaxone and Enrofloxacin in Dogs Anesthetized with Isoflurane: Impact of Hemodynamic and Cardiorespiratory Parameters

Abstract

Background: The prophylactic use of antimicrobials in patients undergoing surgery is widely performed due to its power to reduce and control infections in the surgical site. Metronidazole, ceftriaxone and enrofloxacin are drugs widely used in veterinary medicine, even during anesthesia, either in healthy patients or under critical conditions. Despite several reports on hemodynamic reactions after intravenous application of antimicrobials in dogs, there are few studies on these effects in dogs undergoing anesthesia. The objective of this study was to evaluate the hemodynamic and cardiorespiratory effects of metronidazole, ceftriaxone and enrofloxacin in dogs anesthetized with isoflurane.Materials, Methods & Results: Forty healthy bitches were used, equally divided into four experimental groups of 10 animals each: placebo group (PG), metronidazole group (MG), ceftriaxone group (CG) and enrofloxacin group (EG). After the experimental phase of data collection, all animals were submitted to ovariohysterectomy using the minimally invasive approach. A catheter was placed in the dorsal metatarsal artery for direct blood pressure monitoring, with systolic (SBP), mean (MBP) and diastolic (DBP) blood pressures were continuously monitored by means of a transducer connected to a multiparametric monitor. The others measured data were heart rate (HR), respiratory rate (RR), body temperature (T°C), carbon dioxide expired fraction (ETCO2), oxygen saturation of hemoglobin (SpO2) in T0 (time immediately before performing the treatment), 5 (T5), 10 (T10), 15 (T15), 20 (T20) and 30 (T30) minutes after administration of the antimicrobial. Anesthetic induction was performed with propofol and anesthetic maintenance was performed with isoflurane. After reaching anesthesia with a surgical plan, all parameters were measured before treatments were performed (T0). Then the sodium chloride solution (0.9% NaCl), 25 mg/kg of metronidazole, 30 mg/kg of ceftriaxone or 5 mg/kg of enrofloxacin was administered in cefalic vein. No complications were observed during anesthesia and surgery in all groups. The animals were monitored for three h after the end of the surgery, and then dispensed without prescription of antimicrobials in the recovery period. The HR showed a significant reduction in T5 and T30 compared to the baseline in EG. The RR had a significant increase in T30 in relation to T0 after the administration of 0.9% NaCl in PG. There were no statistically significant changes in HR for groups PG, MG and CG, and RR for groups EG, MG and CG. SBP and MBP had a significant decrease after 30 min of ceftriaxone application. There was a significant decrease in MBP at T5, T10 and T15 compared to baseline in EG. No changes in blood pressure were detected in PG and MG. The ToC showed a significant reduction from T10 to T30 in the GP, from T5 to T30 in the SG, in the T30 in the GM from T20 to T30 in the GC. For all groups, there were no changes in SpO2, ETCO2 and PAD during the study.Discussion: It was concluded that all studied antimicrobials can be used in prophylactic therapy in dogs, in doses recommended by the literature, as the observed changes are subject to correction and can be easily controlled by a qualified anesthetist. The antimicrobial that did not show cardiorespiratory and hemodynamic changes after intravenous application in bitches anesthetized with isoflurane was metronidazole, so its administration was considered safer when compared to enrofloxacin and ceftriaxone, under the conditions of this study, however its indication is punctual, being restricted to cases of infections by anaerobic agents.