Ethmoidal and maxillary nerve block versus systemic opioid administration during rhinoscopy in dogs: a non-randomised clinical trial

OBJECTIVES

This study aimed to evaluate the clinical effects of ethmoidal and maxillary nerve blocks during rhinoscopy in dogs.

MATERIALS AND METHODS

Fourteen dogs underwent rhinoscopy. Under general anaesthesia with isoflurane, ethmoidal and maxillary nerve blocks were applied bilaterally using 2% lidocaine before rhinoscopy in eight dogs (EM group). Six dogs were premedicated with hydromorphone (0.05 mg/kg) as a substitute for local nerve block (H group). During rhinoscopy, the heart rate, arterial blood pressure and end-tidal isoflurane concentration were recorded. The vaporizer setting was adjusted to increase the end-tidal isoflurane concentration when reflex movement was caused by nasal stimulation.

RESULTS

The H group, compared to the EM group, had an increase in HR that was 18 beats/minute (95% CI: 11 to 26) higher, an increase in SAP that was 22 mmHg (12 to 31) higher, an increase in MAP that was 15 mmHg (7 to 23) higher, an increase in DAP that was 12 mmHg (5 to 19) higher, and an increase in end-tidal isoflurane concentration that was 0.4% (0.3 to 0.5) higher. Head movement due to endoscope insertion was observed in 5/6 dogs (83.3%) in the H group and 1/8 dogs (12.5%) in the EM group (odds ratio, 0.029; ra95% CI, 0.001-0.574).

CLINICAL SIGNIFICANCE

Compared with administration of 0.05 mg/kg hydromorphone, concurrent block of the ethmoidal and maxillary nerves can reduce the cardiovascular response, reflex movement and anaesthetic requirement during rhinoscopy in dogs.