Effect of peri-operative crystalloid fluid rate on circulating hyaluronan in healthy dogs: A pilot study.

Hypervolemia can damage the endothelial glycocalyx, a key regulator of vascular permeability, coagulation and inflammation. A starting peri-operative crystalloid fluid rate of 5mL/kg/h is recommended for healthy dogs undergoing elective procedures but higher rates continue to be commonly used. This study aimed to determine if a higher starting perioperative fluid rate was associated with a greater increase in plasma concentrations of hyaluronan, a marker correlated with glycocalyx damage, in systemically healthy dogs undergoing elective surgical procedures. Based on a sample size calculation, 38 dogs undergoing ovariohysterectomy or castration were randomly assigned to receive lactated Ringer's at a starting perioperative fluid rate of 10mL/kg/h (n=19) or 5mL/kg/h (n=19). Plasma hyaluronan concentrations were measured by ELISA in pre- and post-fluid therapy samples. There were no significant differences between groups in hyaluronan values before (baseline, P=0.52) or after perioperative fluid administration (P=0.62). Compared to respective baseline values, hyaluronan values significantly increased following 5 and 10ml/kg/h fluid administration (P=0.02 for both comparisons). This preliminary study identified an increase in hyaluronan over the course of fluid therapy with both the low and high fluid rate. One possible explanation is that both fluid rates contribute to glycocalyx disruption, but it should be emphasized that hyaluronan is not specific to the glycocalyx. Further studies are needed to determine the origin of the increased circulating hyaluronan and its clinical significance in dogs undergoing elective surgical procedures.

Transient pelvic limb neuropathy following proximal metatarsal and tarsal magnetic resonance imaging in seven horses.

BACKGROUND: Pelvic limb neuropathy is a rare post-anaesthetic complication. In the authors' experiences, the incidence of post-anaesthesia neuropathy is increased following MRI of the proximal metatarsus and tarsal regions when compared with previously reported incidences of post-anaesthetic neuropathy. OBJECTIVES: This study reports the incidence, diagnosis, treatment and outcome of seven horses with post-anaesthesia neuropathy following proximal metatarsal and tarsal MRI. STUDY DESIGN: Retrospective case series. METHODS: Case record review of horses receiving general anaesthesia for MRI between 1 January 2012 and 31 December 2017. RESULTS: A total of 1134 MRI procedures were performed and reviewed for analysis. Eight cases of neuropathy were identified in 1088 limb scans (0.74%). Of these cases, one was subsequent to thoracic limb imaging (1/834; 0.12%) and seven were subsequent to imaging of proximal metatarsal and/or tarsal structures (7/181; 3.9%). Following proximal metatarsal and/or tarsal MRI, transient nondependent limb femoral neuropathy developed in six of the seven affected horses, with one additional horse developing peroneal neuropathy of the dependent limb. Recovery of pelvic limb function occurred within 72 h and 9 days in six and one horse, respectively. MAIN LIMITATIONS: Anaesthetic protocol and neuropathy treatment for the affected horses were not standardised. CONCLUSIONS: Though an uncommon complication in horses, transient neuropathy may occur more frequently following MRI of the proximal metatarsal and tarsal structures when compared with other MRI scans. This may be due to patient positioning and the requirement for limb traction for MRI of more proximal regions. Supportive care facilitates rapid return to function.

The clinical effects of a low dose dexmedetomidine constant rate infusion in isoflurane anesthetized cats.

The aim of this study was to evaluate the effects of a low dose dexmedetomidine constant rate infusion (CRI) on cardiopulmonary function, inhalant anesthetic concentration and recovery in isoflurane anesthetized cats. In a prospective, randomized, blinded, controlled design, 12 cats undergoing anesthesia for ovariohysterectomy were administered hydromorphone (0.1mg/kg) intramuscularly, propofol (4.3-7.8mg/kg) intravenously and maintained with isoflurane. During isoflurane anesthesia, the cats were administered either a dexmedetomidine loading dose (0.5µg/kg) followed by a dexmedetomidine CRI (0.5µg/kg/h) (group LDD), or a saline loading dose followed by a saline CRI (group SAL). Heart rate (HR), respiratory rate, blood pressure, temperature, oxygen saturation (SpO2), end tidal carbon dioxide concentration (ETCO2), end tidal isoflurane concentration (ETISO) and anesthetic depth were recorded at nine time points (T0-T8). Overall effects (T1-8) and individual time point results were compared between groups. There were no significant differences in baseline variables (T0), age, weight, propofol dose, anesthesia and surgery time, time to extubation or recovery score between groups. Among the physiological variables measured, significant differences were observed in respiratory rate, ETCO2, and mean and diastolic blood pressure, between groups at individual time points. Systolic blood pressure, HR, SpO2, ETISO and temperature were not significantly different between groups at individual time points. Overall, ETCO2 and ETISO were significantly lower and respiratory rate was significantly higher for LDD compared to SAL. At the doses administered, a CRI of dexmedetomidine reduced isoflurane requirements in anesthetized cats undergoing ovariohysterectomy. The utility of a low dose dexmedetomidine CRI in the perioperative setting requires further investigation, since intraoperative cardiopulmonary values during dexmedetomidine infusion were not different from those receiving saline.

The effects of multiple anaesthetic episodes on equine recovery quality.

BACKGROUND: Although rare, 70% of equine fatalities during recovery from general anaesthesia (GA) are due to catastrophic fractures from poor recovery quality. OBJECTIVE: To determine the effect of repeated GA recovery on GA recovery quality. STUDY DESIGN: Experimental blinded trial. METHODS: Eight adult horses underwent six GA events on sevoflurane for distal limb MRI examination over a 14-week period. Prior to GA recovery, xylazine was administered. Randomly ordered video-recorded GA recoveries were scored by three blinded board certified veterinary anaesthesiologists, unaware of patient identity or GA event number, for nine parameters using a 100 mm visual analogue scale (VAS) where 0 = worst and 100 = best. The number of attempts to stand, duration of lateral and sternal recumbency, total recovery duration and physiologic parameters during each GA event were recorded. Repeated measures ANOVA were used to detect differences. Agreement between observer VAS scores was determined via inter-rater reliability using an intraclass correlation. RESULTS: With GA recovery experience, VAS scores for balance and coordination, knuckling, and overall quality of recovery were improved and the duration of lateral recumbency was increased. There were no differences in total recovery duration, number of attempts to stand, physiologic parameters other than heart rate during GA, or VAS scores for activity in lateral recumbency, move to sternal, move to stand, or strength. MAIN LIMITATIONS: Each GA event was relatively short and there was no surgical stimulation. The same results may not occur if there was surgical stimulation and pain during each GA event. CONCLUSION: Recovery from GA improves with multiple anaesthetic episodes in horses. Clinicians can advise clients that horses are likely to have better GA recovery on repeated GA recovery due to improved balance and coordination and reduced knuckling. Additionally, there is no change in anaesthetic morbidity with six repeated GA events over a 14-week period.

The lack of analgesic use (oligoanalgesia) in small animal practice.

Oligoanalgesia is defined as failure to provide analgesia in patients with acute pain. Treatment of pain in emergencies, critical care and perioperatively may influence patient outcomes: the harmful practice of withholding analgesics occurs in teaching hospitals and private practices and results in severe physiological consequences. This article discusses the prevalence, primary causes, species and regional differences and ways to avoid oligoanalgesia in small animal practice. Oligoanalgesia may be addressed by improving education on pain management in the veterinary curriculum, providing continuing education to veterinarians and implementing pain scales.

The present and future of opioid analgesics in small animal practice.

Opioids are the cornerstone for the treatment of acute pain in small animal patients. This is primarily because of their remarkable safety profile, high efficacy, and benefit of reversibility. There have been some significant advances in our knowledge on opioid pharmacology and clinical usage in companion animal medicine. This review discusses the progression of opioid use in small animal practice providing current misconceptions and controversies in light of routes of administration. Potential targets for research and drug development and novel therapies are discussed in addition to the concepts of glial cell modulators, individual variability, and opioid tolerance and hyperalgesia. The future brings an interesting perspective with the application of pharmacogenetics and individualized pain management in canine and feline practice.