Daniel S. J. Pang

Sedation scales are commonly used to assess sedation levels in dogs, but no threshold scores exist to guide decisions on the need for additional sedatives. The objectives were to determine sedation score thresholds for obtaining orthopedic radiographs without restraint, evaluate inter-rater reliability, and compare video and real-time scoring. Dogs (N = 64) sedated for obtaining various orthopedic radiographs were scored using a validated sedation scale, both in real time (1 rater) and via video assessment (3 raters). Sedation threshold scores were determined using receiver operating characteristic curves and the Youden index based on a rater opinion (yes or no) of whether radiographs could be completed without restraint. Two thresholds were calculated: 1 for all radiograph types and 1 specifically for stifle radiographs. Discrimination between adequately and inadequately sedated dogs was evaluated via the area under the curve (AUC). Inter-rater reliability was assessed using the intraclass correlation coefficient, and agreement between scoring methods was analyzed using the Bland-Altman approach. The threshold sedation scores were ≥ 16/21 (AUC = 0.71) for all radiographs and ≥ 12/21 (AUC = 0.77) for stifle radiographs, both indicating moderate ability to distinguish between adequately and inadequately sedated dogs. The inter-rater reliability of combined scores was very good (intraclass correlation coefficient > 0.81) for all raters, and the mean bias between video and real-time scoring was -0.08. The determined threshold scores can assist clinicians in determining whether additional sedation is necessary. The sedation scale demonstrated high reliability and accuracy, particularly when scored via video.

Providing perioperative analgesia in farm animal species is often hampered by limited analgesic agent availability, legal restrictions, or an absence of licensed products. A 38.7 kg, 6‐month‐old male Boer goat presented for surgical repair of a non‐strangulated umbilical hernia. Following preanaesthetic sedation with intramuscular xylazine (0.05 mg/kg), general anaesthesia was induced with intravenous midazolam (0.2 mg/kg) and ketamine (2.3 mg/kg) and maintained with isoflurane carried in oxygen. An ultrasound‐guided rectus sheath block was performed, with 0.5 mL/kg of lidocaine 1% delivered in each of the two injection sites. Surgery progressed uneventfully, with no indications of nociception: autonomic responses to surgical stimulation were not observed, with stability in heart rate, respiration rate and arterial blood pressure. Yohimbine (0.1 mg/kg) was given intravenously to accelerate recovery and facilitate tracheal extubation. The goat was returned to its owner 1.5 hours after recovery, and the owner reported a rapid return to normal function (eating, drinking and voiding).

To compare sedation following premedication delivered via subcutaneous (SC) injection at or adjacent to the Governing Vessel 20 acupuncture location (GV20adj), interscapular SC injection (iscapSC), or lumbar epaxial intramuscular (IM) injection. Cats receiving ovariohysterectomy or castration surgery, randomly allocated to GV20adj (n = 18), iscapSC (n = 18), or IM (n = 20) groups. Premedication consisted of dexmedetomidine (10 μg/kg) and methadone (0.2 mg/kg). Sedation, infrared temperature (GV20adj and iscapSC sites), and signs of nausea and vomiting were recorded. The GV20adj injection resulted in greater sedation than iscapSC injection (P < 0.05) and similar sedation compared to IM injection. Sedation was more consistent with GV20adj than IM injection. Site temperature was higher at the GV20adj site than the iscapSC site (P < 0.0001). Nausea symptoms were similar between groups (P = 0.209), with increased vomiting in the iscapSC group (15/18 cats) compared to GV20adj (8/18, P = 0.035) and IM groups (9/20, P = 0.021). Sedation via GV20adj injection was similar to, but more consistent than, IM injection, and superior to iscapSC injection. Higher GV20adj site temperature suggested greater perfusion, potentially explaining differences in sedation and vomiting. The GV20adj injection route in cats is a viable route for premedication or sedation.

OBJECTIVE: To collect medication error (ME) data during the perianesthetic period from small animal clinics. SAMPLE: 6 small animal general practice veterinary clinics. METHODS: Small animal general practice veterinary clinics were recruited in this prospective observational study, with staff given a presentation on medical errors and instructed on how to submit medication error reports to an online reporting system. Errors were classified according to type and timing. RESULTS: A total of 2,728 general anesthesia or sedation procedures were performed, with 49 ME reports submitted. One duplicated report of the same error was excluded, resulting in a ME rate of 1.8%. Most reports (69% [33/48]) were near misses. The remaining 31% were MEs that reached the patient but did not cause harm. Wrong dose errors were the most common type (63% [30/48]), of which 80% (24/30) were calculation errors. Premedication/sedation and maintenance were the most reported stages, at 47% (20/43) and 23% (10/43), respectively. None of the MEs reported resulted in an adverse event, with an approximately 2:1 ratio of near-miss to no-harm MEs. The observed patterns of MEs reported, including type and timing, represent a target for further education. CLINICAL RELEVANCE: These results quantify the ME rate in general practice veterinary clinics, providing an initial benchmark for MEs during the perianesthetic period.

Overdose of carbon dioxide gas (CO₂) is a common euthanasia method for rodents; however, CO₂ exposure activates nociceptors in rats at concentrations equal to or greater than 37% and is reported to be painful in humans at concentrations equal to or greater than 32.5%. Exposure of rats to CO₂ could cause pain before loss of consciousness. We used 2 standardized loss of righting reflex (LORR) methods to identify CO₂ concentrations associated with unconsciousness in Wistar, Long–Evans, and Sprague–Dawley rats (n = 28 animals per strain). A rotating, motorized cylinder was used to test LORR while the rat was being exposed to increasing concentrations of CO₂. LORR was defined based on a 15-second observation period. The 2 methods were 1) a 1-Paw assessment (the righting reflex was considered to be present if one or more paws contacted the cylinder after the rat was positioned in dorsal recumbency), and 2) a 4-Paw assessment (the righting reflex was considered to be present if all 4 paws contacted the cylinder after the rat was positioned in dorsal recumbency). Data were analyzed with Probit regression, and dose-response curves were plotted. 1-Paw EC₉₅ values (CO₂ concentration at which LORR occurred for 95% of the population) were Wistar, 27.2%; Long–Evans, 29.2%; and Sprague–Dawley, 35.0%. 4-Paw EC₉₅ values were Wistar, 26.2%; Long–Evans, 25.9%, and Sprague–Dawley, 31.1%. Sprague–Dawley EC₉₅ values were significantly higher in both 1- and 4-Paw tests as compared with Wistar and Long–Evans rats. No differences were detected between sexes for any strain. The 1-Paw EC₉₅ was significantly higher than the 4-Paw EC₉₅ only for Sprague-Dawley rats. These results suggest that a low number of individual rats from the strains studied may experience pain during CO₂ euthanasia.

Euthanasia is one of the most commonly performed procedures in biomedical research, involving tens of millions of animals in North America and Europe every year. The use of sodium pentobarbital, injected intraperitoneally, for killing rodents is described as an acceptable technique by the AVMA and CCAC euthanasia guidelines. This drug and route are recommended over inhalant anesthetics, carbon dioxide, and physical methods for ethical and aesthetic reasons as well as efficiency. However, a growing body of evidence challenges the efficacy and utility of intraperitoneal pentobarbital. This methodology has been described as inconsistent and may induce pain and stress. With these considerations in mind, a review of the literature is needed to assess the evidence surrounding this killing method, the associated welfare implications, and potential for refinement.