Effect of novel metabotropic glutamate receptor 5 antagonist on gastroesophageal reflux in dogs during anaesthesia

Objectives Gastroesophageal reflux during anaesthesia is a common event occurring in dogs with the potential to cause oesophageal injury and aspiration pneumonia. The objective of the current study was to evaluate the effect of the novel metabotropic glutamate receptor 5 antagonist TT001 on gastroesophageal reflux during anaesthesia in dogs using two different protocols. Materials and Methods One hundred and nineteen client-owned dogs were included and randomly assigned to receive test-drug containing either active TT001 (n = 58) or placebo vehicle (n = 61). In protocol 1 (n = 77), test-drug was administered shortly before induction and in protocol 2 (n = 42) test-drug was administered 15 minutes before standardised pre anaesthetic drugs. Gastroesophageal reflux (pH <4) was measured and recorded using oesophageal pHmetry throughout the duration of the anaesthesia. Results Gastroesophageal reflux was registered in 45.4% of dogs, in protocol 1: 44.2%, and in protocol 2: 47.6%. No overall statistically significant difference between the dogs receiving active TT001 (group A, 48.3%) and placebo (group B, 42.6%) was observed, regardless of the protocol tested (protocol 1: group A: 47.4%, group B: 41.0%; protocol 2: group A: 50.0%, group B: 45.5%). Clinical Significance Administration of metabotropic glutamate receptor 5 antagonist TT001 as a single intravenous bolus injection before or after pre-anaesthetic drugs has limited effect on the incidence of gastroesophageal reflux in anaesthetised dogs.