The objectives of the study were to: i) determine baseline microvascular perfusion indices (MPI) and assess their repeatability in healthy horses under general anesthesia, and ii) compare the MPIs of 3 microvascular beds (oral mucosa, colonic serosa, and rectal mucosa). Healthy adult horses were anesthetized and sidestream dark field microscopy was used to collect video loops of the oral mucosa, rectal mucosa, and colonic serosa under normotensive conditions without cardiovascular support drugs; videos were later analyzed to produce MPIs. Baseline MPI values were determined for each site, which included the total vessel density (TVD), perfused vessel density (PVD), portion perfused vessels (PPV), and microcirculatory flow index (MFI). Differences in MPIs between microvascular beds were not statistically significant. Repeatability of the measurements varied for each MPI. In particular, the site of sampling had a profound effect on the repeatability of the PPV measurements and should be considered in future studies.

OBJECTIVE To evaluate the usefulness of injection of indocyanine green (ICG) solution with near-infrared (NIR) fluorescence imaging for transcutaneous detection of sentinel lymph nodes (SLNs) and their associated lymphatic vessels in the oral mucosa of healthy dogs. ANIMALS 6 adult purpose-bred research hounds. PROCEDURES Each dog was sedated, and 1 mL of ICG solution was injected into the gingival mucosa dorsal to the right maxillary canine tooth. Subsequently, NIR fluorescence imaging was used to transcutaneously detect the lymphatic vessels and SLNs. The distance between the injection site and each SLN was measured. Time to first evidence of node fluorescence was recorded, and velocity of ICG movement was calculated. A slide preparation of a fine-needle aspiration sample of the fluorescing structure underwent cytologic examination (to confirm presence of lymphatic tissue) and NIR fluorescence imaging (to confirm presence of ICG). RESULTS The ipsilateral mandibular lymphocentrum was the SLN in all dogs. The time to visually detectable fluorescence ranged from 4 to 15 minutes (mean ± SD, 8.8 ± 3.76 minutes). The mean velocity was 1.94 ± 0.93 cm/min. Fluorescence was not observed in the contralateral lymph nodes. Each fluorescing structure was confirmed to be lymphatic tissue, and NIR fluorescence imaging revealed that ICG was present in the sampled SLN. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that injection of ICG solution with NIR fluorescence imaging can be used to transcutaneously identify SLNs along with associated lymphatic vessels in the oral mucosa of healthy dogs. Time from injection to identification of fluorescence was rapid with prolonged retention of material within the SLN, indicating that this procedure could be performed during surgery.

OBJECTIVE To evaluate hemodynamic, respiratory, and sedative effects of buccally administered detomidine gel and reversal with atipamezole in dogs. ANIMALS 8 adult purpose-bred dogs. PROCEDURES Arterial and venous catheters were placed. Baseline heart rate, respiratory rate, cardiac output (determined via lithium dilution with pulse contour analysis), oxygen delivery, systemic vascular resistance, arterial blood gas values, and sedation score were obtained. Detomidine gel (2.0 mg/m2) was administered on the buccal mucosa. Cardiopulmonary data and sedation scores were obtained at predetermined times over 180 minutes. Atipamezole (0.1 mg/kg) was administered IM at 150 minutes. Reversal of sedation was timed and scored. Data were analyzed with an ANOVA. RESULTS Compared with baseline values, heart rate was lower at 45 to 150 minutes, cardiac output and oxygen delivery were lower at 30 to 150 minutes, and systemic vascular resistance was increased at 30 to 150 minutes. There were no significant changes in Paco2, Pao2, or lactate concentration at any time point, compared with baseline values, except for lactate concentration at 180 minutes. All dogs became sedated; maximum sedation was detected 75 minutes after administration of detomidine. Mean ± SD time to recovery after atipamezole administration was 7.55 ± 1.89 minutes; sedation was completely reversed in all dogs. No adverse events were detected. CONCLUSIONS AND CLINICAL RELEVANCE Buccally administered detomidine gel was associated with reliable and reversible sedation in dogs, with hemodynamic effects similar to those induced by other α2-adrenoceptor agonists. Buccally administered detomidine gel could be an alternative to injectable sedatives in healthy dogs.