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To determine whether moderate hypothermia during anesthesia significantly affects the serum concentration of transdermally delivered fentanyl and whether halothane or isoflurane affect these concentrations. Randomized cross-over experimental trial. Six mature, healthy Beagles (three males, three females) weighing 10.6 ± 0.43 kg. A 50-µg hour−1 fentanyl patch was applied 36 hours prior to anesthesia. Anesthesia was induced at time 0 ( t = 0). Each dog received four treatments: isoflurane + normothermia (ISO-NORM), isoflurane + hypothermia (ISO-HYPO), halothane + normothermia (HAL-NORM), and halothane + hypothermia (HAL-HYPO). Dogs were intubated and maintained at 1.5 times MAC. Animals in the hypothermia treatments were cooled to 35 °C during anesthesia. Serum fentanyl analysis was performed at −36, −24, −12, 0, 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 18, and 26 hours. Direct arterial blood pressures and arterial blood gases were monitored. The mean body temperatures (±SEM) during the anesthetic period for the four treatments were: ISO-NORM = 37.7 ± 0.07 °C, ISO-HYPO = 35.8 ± 0.1 °C, HAL-NORM = 37.7 ± 0.06 °C, and HAL-HYPO = 35.8 ± 0.13 °C. The mean (±SEM) serum fentanyl concentrations (SFC) for both hypothermia treatments were significantly lower than baseline concentrations at t = 1 hour and persisted for the duration of anesthesia for the ISO-HYPO treatment but only from t = 1 to 2 hours for the HAL-HYPO treatment. Serum fentanyl concentrations returned to baseline within one hour of the end of anesthesia, regardless of body temperature. There were no significant differences between treatments for systolic or diastolic blood pressure but mean blood pressures were higher during normothermia versus hypothermia during the last hour of anesthesia. Hypothermia during inhalation anesthesia produced a significant reduction in SFC using transdermal administration and was more protracted with isoflurane than halothane anesthesia. While significant reductions in SFC occurred, the SFC were still within the range believed to confer analgesia. [ABSTRACT FROM AUTHOR]

To determine if low molecular weight synthetic colloid fluids administered to dogs interfere with refractometric estimates of total plasma protein (TPPr) and urine osmolality (UOsm). Experimental study. Eighteen healthy Greyhound dogs. Anaesthetized Greyhounds subjected to haemorrhage for 60 minutes were given 80 mL kg–1 of Plasma-Lyte 148 (CRYST), or 20 mL kg–1 of hydroxyethyl starch 130/0.4 (HES) or succinylated gelatine (GELO) (n = 6 per group) intravenously over 20 minutes. Refractometric (TPPr) and biuret total plasma protein (TPPb) were measured before haemorrhage (Baseline), at end of shock (Shock), immediately (T20), then 40 minutes (T60), 100 minutes (T120) and 160 minutes (T180) after fluid administration. Urine specific gravity (USG) and UOsm were measured at all time points except T20. Estimated UOsm (eUOsm) was calculated from USG. Bias and limits of agreement (LOA) for TPPr versus TPPb, and eUOsm versus UOsm were calculated at each time point. For dogs given CRYST and GELO, median TPPr and TPPb decreased in parallel, with a small consistent TPP bias (CRYST range of bias, 0.38−0.67 g dL–1; GELO range of bias, 0.42−0.58 g dL–1). Dogs given HES showed divergence between median TPPr and TPPb after T20, with a peak bias at T20 of 1.62 g dL–1 (LOA 1.29−1.95). Dogs given HES and GELO had markedly increased USG [HES peak median USG at T180 of 1.119 (Q1−Q3 1.103−1.122); GELO peak median USG at T120 of 1.114 (Q1−Q3 1.082−1.119)], with large increases in bias between eUOsm and UOsm [HES peak bias at T60 of 2995 mOsm kg–1 (LOA 2032−3958 mOsm kg–1); GELO peak bias at T120 of 2465 mOsm kg–1 (LOA 940−3990 mOsm kg–1)]. Administration of HES and GELO to dogs with haemorrhagic shock interferes with refractometric measurements for at least 3 hours after administration. [ABSTRACT FROM AUTHOR]

Objective To determine the cardiovascular and acid-base effects of 6% hydroxyethyl starch (HES) 130/0.4 and 0.9% sodium chloride (NaCl) administered to anaesthetized greyhounds with haemorrhagic shock. Study design Prospective, experimental, complete randomized block design. Animals Twelve healthy adult greyhounds. Methods After 60 minutes of isoflurane anaesthesia, 48 mL kg-1 of blood was removed to induce hypotension. Dogs were randomized to receive either 20 mL kg-1 of HES 130/0.4 or 80 mL kg-1 of 0.9% NaCl over 20 minutes. Haemoglobin, arterial and central venous blood gas and electrolytes, lactate, mean arterial pressure (MAP) and cardiac index were measured at: T0, 60 minutes after induction of anaesthesia, immediately prior to blood removal; T1, immediately after blood removal; T2, immediately after fluid administration; and T3, 40 minutes after fluid administration. Oxygen extraction ratio (O2ER) was calculated at each sample time. Results O2ER increased at T1 and decreased at T2 and T3, with no difference between the two groups. Dogs administered HES 130/0.4 had higher lactate at T2 [mean (95% confidence interval) 1.3 (0.8e1.9) mmol L-1] than dogs administered 0.9% NaCl [0.8 (0.5e1.1) mmol L-1]; p = 0.045. Dogs administered HES 130/0.4 had a higher MAP at T3 [88 (74-102) mmHg] than dogs administered 0.9% NaCl [69 (60-79) mmHg]; p = 0.019. Dogs administered 0.9% NaCl were more acidaemic at T2 and T3, including higher hydrogen ion, lower bicarbonate, lower base excess and higher chloride concentrations. Conclusion and clinical relevance The effect of 20 mL kg-1 of HES 130/0.4 on shock, as measured by O2ER, was no different than that of 80 mL kg-1 of 0.9% NaCl in dogs under general anaesthesia. Acidaemia in the NaCl group is likely attributable to hyperchloraemic metabolic acidosis from the larger volume administered. [ABSTRACT FROM AUTHOR]

To document changes in urinary biomarker concentration and conventional diagnostic tests of acute kidney injury (AKI) following hypotension and fluid resuscitation in anaesthetized dogs. Experimental, repeated measures, prospective study. A group of six male adult Greyhound dogs. Following general anaesthesia, severe hypotension was induced by phlebotomy, maintaining mean arterial blood pressure (MAP) < 40 mmHg for 60 minutes, followed by resuscitation with intravenous gelatine solution to maintain MAP > 60 mmHg for 3 hours. Following euthanasia, renal tissue was examined by light microscopy (LM) and transmission electron microscopy (TEM). Urinary and serum concentrations of neutrophil gelatinase-associated lipocalin (NGAL), cystatin C (CysC), and gamma-glutamyl transpeptidase (GGT), serum creatinine and urine output were measured at baseline and hourly until euthanasia. Data are presented as mean and 95% confidence interval and analysed using repeated measures analysis of variance with Dunnett's adjustment, p < 0.05. Structural damage to proximal renal tubular cells was evident on LM and TEM. Urinary biomarker concentrations were significantly elevated from baseline, peaking 2 hours after haemorrhage at 19.8 (15.1–25.9) ng mL–1 NGAL (p = 0.002), 2.54 (1.64–3.43) mg mL–1 CysC (p = 0.009) and 2043 (790–5458) U L–1 GGT (p < 0.001). Serum creatinine remained within a breed-specific reference interval in all dogs. Urinary protein–creatinine ratio (UPC) was significantly elevated in all dogs from 1 hour following haemorrhage. Urinary NGAL, CysC and GGT concentrations, and UPC were consistently elevated within 1 hour of severe hypotension, suggesting that proximal renal tubules are damaged in the earliest stage of ischaemia-reperfusion AKI. Measurement of urinary biomarkers may allow early diagnosis of AKI in anaesthetized dogs. Urinary GGT concentration and UPC are particularly useful as they can be measured on standard biochemistry analysers. [ABSTRACT FROM AUTHOR]

Abstract: A retrospective analysis was performed to determine the effects of age, breed, parity, and litter size on the duration of gestation in the bitch. Bitches at two locations were monitored from breeding to whelping. A total of 764 litters whelped from 308 bitches (36 large hounds, 34 Golden Retrievers, 23 German Shepherd Dogs (GSD), and 215 Labrador Retrievers). By breed, the number of whelpings was 152, 72, 58, and 482 for the hounds, Golden Retrievers, German Shepherd Dogs, and Labrador Retrievers, respectively. Whelping was predicted to be 57d from the first day of cytologic diestrus in the hounds or 65d from the initial progesterone rise in the other breeds. The average gestation duration (calculated as 8d prior to Day 1 of cytologic diestrus in hounds or measured from the initial progesterone rise in other breeds) by breed (days±S.D.) was 66.0±2.8, 64.7±1.5, 63.6±2.1, and 62.9±1.3 for the hounds, Golden Retrievers, German Shepherd Dogs, and Labrador Retrievers, respectively. The relationship of age, breed, parity, and litter size with the difference in gestation duration was evaluated using log linear modeling. Age or parity had no effect on gestation duration. Compared to Labrador Retrievers, the German Shepherd Dogs, Golden Retrievers and hounds were more likely to have a longer gestation duration; three, four and nearly eight times as likely, respectively. Bitches whelping four or fewer pups were significantly more likely to have a longer gestation duration than those whelping five or more pups; the prolongation averaging 1d. [Copyright &y& Elsevier]

Objective To determine the agreement of invasive blood pressure measured in the facial, metatarsal and carotid arteries, and evaluate the effects of two haemodynamic conditions on agreement. Study design Prospective randomized study. Animals A group of eight horses aged 7 (4–23) years with a body weight of 493 ± 33 kg. Methods Horses were anaesthetized and positioned in dorsal recumbency. Invasive blood pressure was measured simultaneously via catheters placed in the facial, metatarsal and carotid arteries. Cardiovascular function and agreement between arteries was assessed before and during administration of phenylephrine and sodium nitroprusside. These were administered until carotid mean pressure (MAPc) increased or decreased from baseline (65 ± 5) to >90 or <50 mmHg, respectively. Data recorded at each sample time included systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures for carotid (c), facial (f) and metatarsal (m) arteries as well as cardiac output ( Q ˙ t ) and systemic vascular resistance (SVR). Bland–Altman analysis was used to assess agreement between peripheral and central sites, and regression analysis to determine influence of Q ˙ t and SVR. Results The largest difference was observed in SAPc and SAPm with a bias and limits of agreement (LOA) of 2 (−15 to 19) mmHg. The bias (LOA) for MAPc and MAPf was 2 (−4 to 9) mmHg and for MAPc and MAPm was 5 (−4 to 14) mmHg. The best agreement for DAP was seen between DAPc and DAPf with bias (LOA) of 1 (−3 to 5) mmHg. Regression analysis indicated marginal influence on agreement by Q ˙ t on MAPc and MAPf. Conclusions and clinical relevance MAP and DAP of the carotid artery were higher than those of the peripheral arteries, which may lead to overzealous treatment of hypotension, albeit maintaining central pressures. Q ˙ t and SVR did not largely influence the difference between sites. [ABSTRACT FROM AUTHOR]

Objective To determine agreement between invasive blood pressures measured in three peripheral arteries in anaesthetized horses undergoing elective surgery. Study design Prospective balanced incomplete block design. Animals A total of 18 client-owned horses. Methods Invasive blood pressure (IBP) was measured simultaneously in one of the following three combinations: 1) transverse facial and facial artery; 2) transverse facial and metatarsal artery; and 3) facial and metatarsal artery. The agreement in blood pressure measured for each combination was performed in six horses. At each sample time, systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were measured concurrently in each artery, and the mean of three consecutive measurements was recorded. The position of horse, heart rate and use of dobutamine were also recorded. Bland–Altman analysis was used to assess agreement between sites. Results A total of 54 paired measurements were obtained, with 18 paired measurements from each combination. All paired measurements showed poor and haphazard (nonsystematic) agreement. The widest limit of agreement was 51 mmHg for SAP measured in the facial artery and metatarsal artery, with a bias of –11 mmHg. The smallest limit of agreement was 16 mmHg for MAP measured in the transverse facial and metatarsal artery, with a bias of 1 mmHg. Conclusions and clinical relevance There was poor and haphazard agreement for SAP, MAP and DAP measured in each pair of peripheral arteries in this study. These results show that blood pressure measured in different peripheral arteries cannot be used interchangeably. This has implications for studies that use IBP as an outcome variable and studies determining agreement between noninvasive blood pressure and IBP measurements in horses under general anaesthesia. [ABSTRACT FROM AUTHOR]

Objective To determine changes in urine neutrophil gelatinase-associated lipocalin concentration ( uNGAL) in anaesthetized Greyhound dogs that developed acute tubular damage following haemorrhage and resuscitation with colloid-based fluids. Study design Prospective experimental study. Animals Seven healthy adult entire male Greyhound dogs. Methods During isoflurane anaesthesia, approximately 50 mL kg−1 of blood was removed to maintain mean arterial pressure ( MAP) ≤40 mmHg for 1 hour followed by gelatin-based colloid administration to maintain MAP ≥60 mmHg for 3 hours. Data, including oxygen extraction ratio and uNGAL, were collected before (T0) and immediately following (T1) haemorrhage, and hourly during reperfusion (T2-T4). After T4, dogs were euthanized and renal tissue was collected for histology. Statistical analysis was performed using repeated-measures one-way anova. Data are presented as means (95% confidence interval). Results Histology identified renal tubular epithelial damage in all dogs. Urine NGAL concentration increased from 12.1 (0-30.6) ng mL−1 at T0 to 122.0 (64.1-180.0) ng mL−1 by T3. Compared with T0, uNGAL was significantly higher at T3 ( p = 0.016) and was increased 24-fold. Conclusions and clinical relevance Despite wide individual variation in baseline uNGAL, increases in uNGAL were observed in all dogs, suggesting that this biomarker has the potential to detect renal tubular injury following haemorrhage-induced hypotension and colloid-mediated reperfusion. [ABSTRACT FROM AUTHOR]

Objective To compare adequacy of oxygen delivery and severity of shock during maintenance of anaesthesia with isoflurane or alfaxalone infusion in greyhounds experiencing blood loss. Study design Prospective, randomised study. Animals Twenty-four greyhounds (ASA I). Methods All greyhounds were premedicated with methadone (0.2 mg kg−1) intramuscularly. Anaesthesia was induced with alfaxalone 2.5 mg kg−1intravenously. Following endotracheal intubation, the dogs were connected to an anaesthetic circle circuit delivering oxygen. Dogs were allocated to receive inhaled isoflurane or an intravenous infusion of alfaxalone for maintenance of anaesthesia. Isoflurane was initially administered to achieve an end-tidal concentration of 1.4% and alfaxalone was initially administered at 0.13 mg kg−1 minute−1. The dose of isoflurane or alfaxalone was adjusted during instrumentation to produce a clinically equivalent depth of anaesthesia. All dogs were mechanically ventilated to normocapnia (PaCO2 35-40 mmHg; 4.67-5.33 kPa). Passive warming maintained core body temperature between 37 and 38 °C. Measured and calculated indices of cardiovascular function, including mean arterial blood pressure ( MAP), cardiac index ( CI), systemic vascular resistance index ( SVRI), oxygen delivery index ( [ABSTRACT FROM AUTHOR]