OBJECTIVE To determine pharmacokinetic and pharmacodynamic properties of the injectable formulation of dexmedetomidine administered via the oral transmucosal (OTM) route to healthy dogs. ANIMALS 6 healthy dogs. PROCEDURES Injectable dexmedetomidine was administered IV (5 μg/kg) or via the OTM route (20 μg/kg) in a blinded, single-observer, randomized crossover study. Dogs received dexmedetomidine and a sham treatment at each administration. Serial blood samples were collected from a catheter in a saphenous vein. Heart rate, respiratory rate, and subjective sedation score were assessed for 24 hours after administration. Plasma samples were analyzed for dexmedetomidine concentrations by use of ultraperformance liquid chromatography–tandem mass spectrometry. RESULTS For the OTM route, the mean ± SD maximum plasma concentration was 3.8 ± 1.3 ng/mL, which was detected 73 ± 33 minutes after administration. The mean maximum concentration for the IV dose, when extrapolated to the time of administration, was 18.6 ± 3.3 ng/mL. The mean terminal-phase half-life was 152 ± 146 minutes and 36 ± 6 minutes for OTM and IV administration, respectively. After IV administration, total clearance was 8.0 ± 1.6 mL/min/kg and volume of distribution at steady state was 371 ± 72 mL/kg. Bioavailability for OTM administration of dexmedetomidine was 11.2 ± 4.5%. Peak sedation scores did not differ significantly between routes of administration. Decreases in heart rate, respiratory rate, and peak sedation score were evident sooner after IV administration. CONCLUSIONS AND CLINICAL RELEVANCE OTM administration of the injectable formulation of dexmedetomidine resulted in a similar degree of sedation and prolonged duration of action, compared with results for IV administration, despite relatively low bioavailability.

AIMS: To determine efficacy of a minimally invasive (MI) surgical approach using a human MI lumbar retractor for canine lumbosacral dorsal laminectomy and partial discectomy and to compare this technique to the standard open surgical (OS) approach.METHODS: Lumbosacral dorsal laminectomy and partial discectomy was performed on 16 largebreed canine cadavers using either a standard OS (n=8) or MI (n=8) approach. Skin and fascial incision length, procedure time, and intraoperative complications were recorded. Postoperatively specimens were evaluated for laminectomy and discectomy dimensions, and visible damage to the cauda equina and exiting nerve roots.RESULTS: Median length of skin and fascial incisions in the OS group were longer than in the MI group (p<0.001). Median laminectomy length was similar between both approaches (p=0.234) but width was greater for the MI than OS approach (p=0.002). Both approaches achieved similar partial discectomy width (p=0.279). Overall surgical time was longer for MI approaches compared to OS, with a median of 18.5 (min 15.5, max 21.8) minutes for MI compared to 14.6 (min 13.1, max 16.9) minutes for OS (p=0.001).CONCLUSIONS: The MI approach reduced incision lengths while retaining comparable laminectomy and discectomy dimensions. For this in vitro model the MI approach required more time to complete, but this difference may not be relevant in clinical cases.

Objective: To describe a novel surgical technique for ventral orbital reconstruction after ventral orbitectomy by using a temporalis fascia transposition flap. Study design: Case report. Methods: A 7-year-old, spayed female Boston terrier was treated for multilobular osteochondrosarcoma arising from the cranial aspect of the left zygomatic arch, causing asymmetry of the face and mild exophthalmos of the left eye. A ventral orbitectomy with a wide surgical excision (including the cranial aspect of the zygomatic bone, the medial aspect of the lacrimal bone, and the dorsal aspect of the maxilla) was performed with preservation of the left eye. To support and maintain the left eye in a normal position, a temporalis fascia transposition flap was elevated and used. No complications occurred during the procedure. Results: Thirteen days after surgery, the referring veterinarian reported no complications. Complete excision was confirmed on histopathology. Eighty-three days after surgery, the dog remained asymptomatic with only mild epiphora of the left eye. Follow-up information from the owner 11 months after surgery indicated that the dog was asymptomatic with minimal ventral globe deviation. Conclusion: Additional ventral support of the globe after ventral orbitectomy via a temporalis fascia transposition flap resulted in an excellent functional and cosmetic outcome. Clinical significance: A temporalis fascia transposition flap can be used to reconstruct the ventral aspect of the orbit in dogs.

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OBJECTIVE To determine the pharmacokinetics and pharmacodynamics of dexmedetomidine after IM administration in dogs. ANIMALS 6 healthy adult purpose-bred dogs (3 males, 3 females) with a mean ± SD body weight of 25.2 ± 1.8 kg. PROCEDURES Each dog received 10 µg/kg dexmedetomidine, IM. Heart rate and respiratory rate were counted via cardiac auscultation and visual assessment of chest excursions. Sedation was assessed utilizing 2 sedation scoring systems. Plasma concentrations were determined using ultra performance liquid chromatography–mass spectrometry. Plasma concentrations versus time data after IM dexmedetomidine were analyzed using noncompartmental analysis for extravascular administration. RESULTS Over the first 2 hours following IM injection of dexmedetomidine, plasma concentrations fluctuated in each dog. The geometric mean (range) maximum plasma concentration was 109.2 (22.4 to 211.5) ng/mL occurring at 20.5 (5 to 75) minutes, and the mean half-life was 25.5 (11.5 to 41.5) minutes. Heart rate was significantly lower than baseline from 30 minutes to 2 hours postdexmedetomidine administration, and respiratory rate was significantly lower than baseline from 45 minutes to 1.75 hours. Dogs were significantly more sedated from 30 minutes to 1.5 hours postdexmedetomidine administration. Median time to onset of sedation was 7.5 minutes (range, 2 to 10 minutes), and median time to peak sedation was 30 minutes (range, 15 to 60 minutes). CLINICAL RELEVANCE Variations in plasma concentrations occurred in all dogs for the 2 hours postinjection of dexmedetomidine at 10 µg/kg, IM. This was likely due to alterations in absorption due to dexmedetomidine-induced local vasoconstriction. Despite variable plasma concentrations, all dogs were sedated following IM dexmedetomidine administration.