Anesthetic management and anesthesia-related complications in dogs with a dilated cardiomyopathy phenotype: a retrospective study of 30 dogs (2010-2024).

OBJECTIVE: To describe perioperative anesthetic management in canines with a dilated cardiomyopathy (DCM) phenotype and to compare the frequency of general anesthesia-related complications with a control group of dogs without heart disease. ANIMALS: 30 dogs with DCM phenotype (cases) and 30 dogs without heart disease (controls). METHODS: Dogs presented to a teaching hospital between 2010 and 2024 that were diagnosed with a DCM phenotype via echocardiography were included in this study. Controls were dogs that presented during the same time period and were matched with cases based on their age, breed, and type of procedure; however, no standardization of treatment between the groups was performed. Medical records were reviewed to evaluate the occurrence of anesthetic complications. RESULTS: Of dogs with a DCM phenotype, 2 had overt DCM, 22 had occult DCM, and 6 had equivocal DCM. Dogs with DCM exhibited a lower likelihood of being premedicated with dexmedetomidine or induced with propofol. Conversely, DCM dogs were more likely to be induced with etomidate or midazolam compared to their counterparts without DCM. Dogs with DCM demonstrated an increased likelihood of experiencing cardiac arrhythmias during anesthesia, received comparatively lower volumes of IV fluids, and were more likely to be administered dobutamine during anesthesia. No significant differences were identified in terms of postanesthesia complications or survival rates to discharge. CLINICAL RELEVANCE: Dogs with a DCM phenotype, primarily characterized by asymptomatic presentation, demonstrated comparable perioperative outcomes under general anesthesia when compared to matched controls, though the lack of standardization in anesthetic management limits definitive conclusions.

Analgesic effects of a retrobulbar block with 0.75% ropivacaine in dogs undergoing enucleation.

OBJECTIVE: To assess the analgesic effects of a retrobulbar block with ropivacaine in dogs undergoing enucleation. STUDY DESIGN: Prospective, randomized, masked placebo-controlled trial. ANIMALS: A total of 23 client-owned dogs. METHODS: Dogs were randomized to be administered a preoperative inferior-temporal palpebral retrobulbar injection of either ropivacaine 0.75% (1 mL 10 kg-1; group RG) or equivalent volume of 0.9% saline (control; group CG). Intraoperative variables recorded to detect a response to noxious stimuli included heart rate (HR) and mean arterial pressure (MAP). Three observers assessed and recorded pain using a numerical rating pain scale and visual analog scale (VAS) before anesthesia (baseline) and postoperatively at 0, 0.5, 1, 2, 3, 4, 5, 6 and 24 hours after extubation. Rescue analgesia was administered if intraoperative HR or MAP increased by ≥ 20% from the previously recorded surgical time point, average postoperative pain scores totaled ≥ 9/20, scored ≥ 3/4 in any one category with VAS ≥ 35/100, or if VAS was ≥ 35/100 with a palpation score > 0/4. RESULTS: Intraoperatively, there was no significant difference in HR or MAP between groups. Rescue analgesia was administered intraoperatively to four and one dogs and postoperatively to five and seven dogs in groups CG and RG, respectively, with no significant difference between groups. VAS scores were significantly lower in ropivacaine dogs at extubation (p = 0.02), but not at other postoperative time points. Adverse events were not observed in either group. CONCLUSIONS AND CLINICAL RELEVANCE: Preoperative retrobulbar 0.75% ropivacaine injection (1 mL 10 kg-1) provided analgesia in dogs following enucleation at extubation; however, intraoperative and postoperative pain control did not differ from a placebo injection with saline. Lack of differences between groups may have been influenced by sample size limitations.

Bone Marrow Aspiration Does Not Induce a Measurable Pain Response Compared to Sham Procedure.

Bone marrow is commonly collected from horses for regenerative medicine applications. Little information is available regarding pain experienced by the horse during bone marrow aspiration. The objective of this study was to characterize horse reaction and pain response during bone marrow aspiration (BMA) compared to a sham (SHAM) procedure. We hypothesized there would be significantly greater horse reaction or pain response measured by salivary cortisol, heart rate variability, and depth and duration of sedation between BMA and SHAM. Twelve university owned horses underwent a BMA and sham procedure, 4 weeks apart in a randomized cross-over design, while sedated with 0.4 mg/kg xylazine hydrochloride. As measures of sedation depth, head height was recorded and sedation level was scored at specific procedural time points. Salivary cortisol was measured immediately before and 2 h after each procedure. Heart rate variability was assessed before, during, and after each procedure. There were no differences in head height, sedation score, or salivary cortisol between groups. No differences were noted between groups in heart rate variability before or during the procedure, but there was a significant decrease in low frequency/high frequency (LF/HF) ratio after the procedure in the BMA group. Over time, there was a significant reduction in LF/HF ratio during the procedure in both groups. Overall, BMA from the sternum did not result in a measurable pain response during, or in the 2 h following the procedure, in comparison to a sham procedure.

Effects of oxymorphone hydrochloride or hydromorphone hydrochloride on minimal alveolar concentration of desflurane in sheep.

OBJECTIVE: To establish the minimum alveolar concentration (MAC) of desflurane and evaluate the effects of 2 opioids on MAC in sheep. ANIMALS: 8 adult nulliparous mixed-breed sheep. PROCEDURES: A randomized crossover design was used. Each sheep was evaluated individually on 2 occasions (to allow assessment of the effects of each of 2 opioids), separated by a minimum of 10 days. On each occasion, sheep were anesthetized with desflurane in 100% oxygen, MAC of desflurane was determined, oxymorphone (0.05 mg/kg) or hydromorphone (0.10 mg/kg) was administered IV, and MAC was redetermined. Physiologic variables and arterial blood gas and electrolyte concentrations were measured at baseline (before MAC determination, with end-tidal desflurane concentration maintained at 10%) and each time MAC was determined. Timing of various stages of anesthesia was recorded for both occasions. RESULTS: Mean ± SEM MAC of desflurane was 8.6 ± 0.2%. Oxymorphone or hydromorphone administration resulted in significantly lower MAC (7.6 ± 0.4% and 7.9 ± 0.2%, respectively). Cardiac output at MAC determination for desflurane alone and for desflurane with opioid administration was higher than that at baseline. No difference was identified among hematologic values at any point. Effects of oxymorphone and hydromorphone on durations of various stages of anesthesia did not differ significantly. CONCLUSIONS AND CLINICAL RELEVANCE: MAC of desflurane in nulliparous adult sheep was established. Intravenous administration of oxymorphone or hydromorphone led to a decrease in MAC; however, the clinical importance of that decrease was minor relative to the effect in other species.