Effects of general anaesthesia in dorsal recumbency with and without vatinoxan on bronchoalveolar lavage cytology of healthy horses

H Rossi,M Raekallio,M Määttä,H Tapio,M Hanifeh,J Junnila,M.M Rajamäki,A Mykkänen

doi:10.1016/j.tvjl.2019.105352

H Rossi, M Raekallio + Show 6 more

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https://doi.org/10.1016/j.tvjl.2019.105352

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Abstract

Pneumonia is one of the potential complications of general anaesthesia in horses. Anaesthesia is known to increase neutrophils in bronchoalveolar lavage fluid (BALF) of horses after lateral recumbency, but studies after dorsal recumbency are lacking. Our primary aim was to determine when lung inflammation reaches its maximum and how rapidly BALF cytology returns to baseline after anaesthesia in dorsal recumbency. A secondary aim was to investigate the possible effect of vatinoxan, a novel drug, on the BALF cytology results.Six healthy experimental horses were enrolled in this observational crossover study. The horses were subject to repeated BALF and blood sampling for 7 days after general anaesthesia with two treatment protocols, and without anaesthesia (control). During the two treatments, the horses received either medetomidine-vatinoxan or medetomidine-placebo as premedication, and anaesthesia was induced with ketamine-midazolam and maintained with isoflurane for 1h in dorsal recumbency. The differences in BALF and blood variables between the two anaesthesia protocols and control were analysed with repeated measures analysis of variance models.In this study, anaesthesia in dorsal recumbency resulted in no clinically relevant changes in airway cytology that could be differentiated from the effect of repeated BALF sampling. No differences in BALF matrix metalloproteinase gelatinolytic activity could be detected between the two treatments or the control series. Marked increase in serum amyloid A was detected in some animals. Vatinoxan as premedication did not consistently affect lung cytology or blood inflammatory markers after anaesthesia.

Highlights

The complication rate in equine general anaesthesia is considered high compared with that in several other species (Johnston et al, 2002; Brodbelt, 2009)
The primary aim of this study was to investigate the effect of general anaesthesia in dorsal recumbency on equine lower airway cytology and selected inflammatory biomarkers in clinically healthy horses, and to evaluate how rapidly the cytology recovers after anaesthesia
One horse presented with cough on a single day during the washout period after the first anaesthesia (MED), and two horses presented with cough during the bronchoalveolar lavage fluid (BALF) sampling period after the MED + V anaesthesia

Summary

Introduction

The complication rate in equine general anaesthesia is considered high compared with that in several other species (Johnston et al, 2002; Brodbelt, 2009). Postanaesthetic pneumonia has been described as one of the potential complications of general anaesthesia in horses (Grubb and Muir, 2005; Monticelli and Adami, 2019). General anaesthesia causes atelectasis and gas-exchange impairment in the lungs (Nyman et al, 1990). Horses are often subjected to mechanical ventilation during general anaesthesia, which can cause trauma and inflammation, as reported in other species (Dos Santos and Slutsky, 2000). The effects of general anaesthesia on inflammatory responses in the lungs and on systemic inflammatory markers, such as serum amyloid A (SAA) are poorly understood in horses

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