Electromyography (EMG) is used to understand muscle activity patterns in animals. Understanding how much variation exists in muscle activity patterns in homologous muscles across animal clades during similar behaviours is important for evaluating the evolution of muscle functions and neuromuscular control. We compared muscle activity across a range of archosaurian species and appendicular muscles, including how these EMG patterns varied across ontogeny and phylogeny, to reconstruct the evolutionary history of archosaurian muscle activation during locomotion. EMG electrodes were implanted into the muscles of turkeys, pheasants, quail, guineafowl, emus (three age classes), tinamous and juvenile Nile crocodiles across 13 different appendicular muscles. Subjects walked and ran at a range of speeds both overground and on treadmills during EMG recordings. Anatomically similar muscles such as the lateral gastrocnemius exhibited similar EMG patterns at similar relative speeds across all birds. In the crocodiles, the EMG signals closely matched previously published data for alligators. The timing of lateral gastrocnemius activation was relatively later within a stride cycle for crocodiles compared to birds. This difference may relate to the coordinated knee extension and ankle plantarflexion timing across the swing-stance transition in Crocodylia, unlike in birds where there is knee flexion and ankle dorsiflexion across swing-stance. No significant effects were found across the species for ontogeny, or between treadmill and overground locomotion. Our findings strengthen the inference that some muscle EMG patterns remained conservative throughout Archosauria: for example, digital flexors retained similar stance phase activity and M. pectoralis remained an 'anti-gravity' muscle. However, some avian hindlimb muscles evolved divergent activations in tandem with functional changes such as bipedalism and more crouched postures, especially M. iliotrochantericus caudalis switching from swing to stance phase activity and M. iliofibularis adding a novel stance phase burst of activity. K E Y W O R D S evolution, locomotion, morphology, musculoskeletal system, neural control
20Objectives The aim of this study was to optimize dexmedetomidine and alfaxalone 21 dosing, for intramuscular administration with butorphanol, to perform minor surgeries 22 in cats. 23Methods Initially, cats were assigned to one of 5 groups, each composed of 6 animals 24 and receiving, in addition to 0.3 mg/kg butorphanol IM, one of the following: A: 0.005 25 mg/kg dexmedetomidine, 2 mg/kg alfaxalone; B: 0.008 mg/kg dexmedetomidine, 1.5 26 mg/kg alfaxalone; C: 0.012 mg/kg dexmedetomidine, 1 mg/kg alfaxalone; D: 0.005 27 mg/kg dexmedetomidine, 1 mg/kg alfaxalone; and E: 0.012 mg/kg dexmedetomidine, 2 28 mg/kg alfaxalone. Thereafter, a modified "direct search" method, conducted in a 29 stepwise manner, was used to optimize drugs dosing. The quality of anaesthesia was 30 evaluated on the basis of composite scores (one for anaesthesia and one for recovery), 31 of Visual Analogue Scales, and of propofol requirement to suppress spontaneous 32 movements. The medians or means of these variables were used to rank the treatments: 33 "unsatisfactory" and "promising" combinations were identified to calculate, through the 34 equation first described by Berenbaum in 1990, new dexmedetomidine and alfaxalone 35 doses to be tested in the next step. At each step, 5 combinations (one new plus the best 36 previous four) were tested. 373 Results None of the tested combinations resulted in adverse effects. Four steps and 120 38 animals were necessary to identify the optimal drug combination (0.014 mg/kg 39 dexmedetomidine, 2.5 mg/kg alfaxalone and 0.3 mg/kg butorphanol). 40Conclusions and relevance The investigated drug mixture, at the doses found with the 41 optimization method, is suitable for cats undergoing minor clinical procedures. 42 43
Summary
No published reports on the occurrence of Mendelson's syndrome (pneumonitis caused by aspiration during anaesthesia) in horses were found in the literature. Although the peculiar anatomy of the equine stomach makes horses less prone than other species to regurgitate, gastric reflux may still occur in horses with colic under certain circumstances. The colic horses in this report had in common stomach impaction, abdominal distention and preanaesthetic placement of a nasogastric tube, which was not withdrawn prior to induction. In both cases, a significant volume of gastric reflux was noted pouring from the endotracheal tube during general anaesthesia for exploratory laparotomy. It was hypothesised that the cause of gastric reflux was the combination of increased intra‐abdominal pressure and patency of the cardia, and that inhalation of gastric content occurred at induction, before tracheal intubation. Treatment, which failed to improve oxygenation, consisted of repositioning of the horses to facilitate passive drainage of gastric content from the airways, active suction through the endotracheal tubes, ventilation strategies, improvement of haemodynamics to increase the pulmonary perfusion, and administration of bronchodilators. One horse was subjected to euthanasia owing to poor prognosis. Aspiration pneumonitis should be regarded as a life‐threatening, although rare, perianaesthetic complication in equine colic cases. Patency of the cardia and increased intra‐abdominal pressure are possible predisposing factors. Partial or even total withdrawal of the nasogastric tube prior to anaesthetic induction and tracheal intubation performed with the horse positioned in sternal recumbency may be undertaken as preventive measures in patients at high risk of developing Mendelson's syndrome.
Background: Osteoarthritis (OA) is common in dogs and causes chronic pain that affects the quality of life and may not respond to analgesics.Objective: The objective of this study was to determine whether low-level laser therapy (LLLT) would improve the quality of life and help reducing systemic analgesics, in dogs with OA.Methods: Seventeen client-owned dogs diagnosed with OA and associated pain were included. The diagnosis of OA was confirmed by orthopedic and radiographic examination. Pain was evaluated in each dog with the canine brief pain inventory (CBPI), compiled by the dog owners, as well as with a visual analog scale (VAS) and the colorado state canine chronic pain scale, used by the clinician. The LLLT was performed weekly in each study dog, for a total period of 6 weeks. The CBPI was then repeated at 2, 4, 6, and 8 weeks after the first laser session, whereas the VAS was reassessed at weeks 2 and 6. The dogs were observed for the occurrence of laser-related side effects.Results: Both CBPI and VAS were significantly reduced after the first laser session (9.2 ± 3.8 and 5.2 ± 1.1, respectively) compared to pretreatment values (11.8 ± 3.6 and 7.6 ± 0.9, respectively; and p = 0.018 and p < 0.001, respectively) and continued to decrease over time until the end of the therapy. Based on these results and improved function, as assessed by the orthopedic surgeon, the pharmacological analgesic therapy was reduced by the clinician at week 2 in 13 of 17 dogs. Laser-related side effects were not observed.Conclusion: This retrospective report provides a basis for future investigations, needed to clarify whether laser therapy may be beneficial to treat canine OA-associated pain. The preliminary findings are promising and suggest that LLLT may help reducing the analgesic administration and improving client satisfaction and the quality of life of dogs with OA.
Keywords: Canine osteoarthritis, Chronic pain, Low-intensity laser therapy, Orthopedic pain.
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