EXPRESS: EFFECTS OF INTRAMUSCULAR AND INTRANASAL ADMINISTRATION OF MEDETOMIDINE ON SEDATION AND SOME CARDIOPULMONARY VARIABLES IN HEALTHY CATS

Objectives To compare the sedative and cardiopulmonary effects following either intranasal (IN) or intramuscular (IM) administration of medetomidine in healthy male cats undergoing neuter procedure. Methods A total of 26 client-owned healthy cats, aged 7 – 60 months, weighing 4 [3-6] kg (median [min-max]) presented for neutering were included in this blinded, randomized, prospective clinical study. The cats were randomly assigned in two groups to receive medetomidine (40 µg/kg) by IN (16 cats) or IM (10 cats) routes. Sedation was scored during premedication (just before and 10, 15, 20 minutes after medetomidine administration) and during recovery (at the moment of orotracheal extubation, 1 and 2 hours after) with a simple descriptive scale (SDSS) ranging from 0 (no sedation) to 3 (maximum sedation) and a composite scale (CSS) ranging from 0 (no sedation) to 19 (maximum sedation). Heart rate (HR), respiratory frequency (RR), non-invasive arterial blood pressure (NIBP) and haemoglobin oxygen saturation (SpO2) were recorded at the same time points as sedation was assessed. Results Sedation scores significantly increased for both groups at all time points after medetomidine administration. However, cats in the IM group achieved a higher maximal sedation score and earlier than cats in the IN group (CSSmax 16 [13-17] at TCSSmax 18 [10-20] min versus 14 [9-17] at 20 [15-20] min respectively). HR significantly decreased in both groups after medetomidine administration, but decrease was less pronounced and shorter in IN group. Regarding adverse effects, sneezing, swallowing and vomiting were significantly increased immediately after IN administration. Conclusions and relevance IN medetomidine (40 µg/kg) can be an alternative, non-invasive route to IM administration for premedicating healthy cats before general anaesthesia for neutering. IN medetomidine premedication produced sufficient sedation with a slower onset and shorter duration but less cardiovascular effects compared to IM in cats.