Sublingual administration of detomidine in horses: Sedative effect, analgesia and detection time

Abstract

A single dose of 40μg/kg bodyweight (BW) of oromucosal detomidine gel was administered sublingually to 10 healthy Dutch Warmblood mares aged 7±4years (mean±SD) and BW 580±69kg. Blood and urine samples were collected before and for 8days following administration and evaluated qualitatively in an FEI Reference Laboratory and quantitatively in a research laboratory. Clinical effects were evaluated at baseline and for 24h after administration. Sedation was determined using head height and scores of reaction to auditory and mixed auditory/sensory stimuli. Mechanical nociceptive thresholds (MNTs) were assessed using pressure algometry to evaluate analgesia. Heart rate (HR) was measured and ataxia scored.All horses were considered negative for detomidine in blood samples by 48h post-administration and in urine by 60h. These results indicated that a safe withdrawal time for detomidine oromucosal gel may be 72h following a single sublingual administration of 40μg/kgBW. Decreases in HR and head height were maximal at 40 and 60min post-administration, respectively. The maximal decrease in response to stimuli was observed at 100min. Ataxia was maximal at 60min. At 40 and 80min MNTs were significantly increased compared to baseline. All parameters, except the MNTs of two locations, which were decreased, returned to baseline values within 24h post-administration.