MethodsDogs were anaesthetised with a standardised protocol. The proportion of dogs with invasively measured MAP <60 mmHg for ≥10 min was recorded. The area under the MAP*time curve (MAP-AUC) was calculated for a standard perioperative period. The association of explanatory variables, including sex, age, body mass and indices of hydration (urine specific gravity (USG), packed cell volume and total solids) measured prior to surgery, with the MAP-AUC was explored using regression analysis in the first cohort (n = 71) and externally validated in the second cohort (n = 24). ResultsIn cohort 1, 35 of 71 dogs (0.49, 95% confidence interval (CI) 0.37-0.61) dogs and 17/24 dogs in cohort 2 (0.71, 95% CI 0.53-0.89) developed hypotension. Regression analysis showed that age and USG were significantly associated with MAP-AUC for cohort 1 (P = 0.0138). There was a positive association of MAP-AUC with age and a negative association with USG. The association of MAP-AUC with USG was supported in cohort 2, with a significant negative association (P = 0.014, r = −0.54) ConclusionThe high frequency of hypotension in both cohorts supports blood pressure monitoring during anaesthesia of young, healthy dogs. USG, an index of hydration, appears negatively associated with MAP during anaesthesia, suggesting that subclinical dehydration may contribute to lower MAP during surgical anaesthesia.

Optimal mechanical ventilation of the pregnant ewe during anaesthesia is of vital importance for maintaining fetal viability. This study aimed to compare peak inspiratory pressure (PIP), oxygenation and cardiovascular parameters with pressure-control (PCV) or volume-control (VCV) mechanical ventilation of anaesthetized pregnant sheep. Twenty ewes at 110 days gestation underwent general anaesthesia in dorsal recumbency for fetal surgery in a research setting. All the sheep were mechanically ventilated; one group with PCV (n ¼ 10) and another with VCV (n ¼ 10) to maintain normocapnia. PIP, direct arterial blood pressure, heart rate, arterial pH and arterial oxygen tension were recorded. PIP was lower in the PCV group (P < 0.001). Arterial oxygen tension was higher in the PCV group (P ¼ 0.013). Mean and diastolic pressures were lower in the PCV group (P ¼ 0.029 and P ¼ 0.047, respectively). Both VCV and PCV provide adequate oxygenation of pregnant sheep anaesthetized in dorsal recumbency, though PCV may provide superior oxygenation at a lower PIP.

seen does not explain the significant phenotypic heterogeneity observed in NM patients or mouse models, suggesting that additional factors determine disease phenotype. Proteomic assessments of skeletal muscles from the Acta1 H40Y, Acta1 D286G, and Neb cKO mouse models of NM identified cellular pathways affected in all mouse models. Interestingly, mitochondrial dysfunction was present in all models, yet different mitochondria-associated proteins were affected. These results suggested that mitochondrial function was differentially impaired in different NM models. Biochemical assays including respirometry, complex activity function of each element of the electron transport chain, glutathione, and citrate synthase were performed to identify specific dysfunctions. Respirometry revealed mitochondrial impairment relative to wildtype counterparts in the Acta1 H40Y and Neb cKO mouse models but not the Acta1 D286G mouse model. Citrate synthase and glutathione show all normal levels in mutant animals relative to their controls, suggesting that the dysfunction lies in the respiratory chain. Electron transport chain analysis is currently ongoing. These studies form a foundation for future work on the impact of mitochondrial dysfunction in NM and its role in phenotype variability in NM, with the ultimate goal of guiding the development of treatment strategies.

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