The analgesic effects of magnesium in veterinary patients: a qualitative evidence synthesis.

OBJECTIVE: To perform a qualitative evaluation of the analgesic effects of magnesium in domestic animals, including its anaesthetic sparing effects. STUDY DESIGN: All database searches were made using PubMed and Google Scholar. Studies published after 1990, evaluating the use of magnesium and reporting information on analgesia, in dogs, cats, horses, cows, goats and sheep were selected (last search in August 2023). A reference check in the selected papers was performed to identify any study which was omitted. The CERQual (Confidence in Evidence from Reviews of Qualitative research) approach was used to assess confidence and analyse the evidence. RESULTS: A total of 20 studies relevant to the analgesic effects of magnesium in veterinary patients and two reviews were included. All were published after 2006. Of the 20, five studies provided information about analgesia in the postoperative period in dogs with heterogenous results. Magnesium added epidurally increased the duration of the sensory block in several species. Motor block was also observed when added to spinal analgesia. Results regarding volatile agents sparing effect were conflicting. Occasional moderate adverse effects were reported in dogs, such as nausea and vomiting, when administered as a bolus in conscious animals, and hypotension when administered intraperitoneally. Collapse was reported in horses after epidural administration. CONCLUSIONS AND CLINICAL RELEVANCE: The evidence of an analgesic effect of magnesium in veterinary patients remains scarce considering the paucity and low quality of published data. Further research may be helpful to establish the efficacy and indications of magnesium in multimodal analgesia in animals.

The influence of hypoxaemia, hypotension and hypercapnia (among other factors) on quality of recovery from general anaesthesia in horses.

OBJECTIVE: To investigate the effect of hypoxaemia, hypotension and hypercapnia, among others, on quality of recovery from general anaesthesia in horses. STUDY DESIGN: Retrospective, single-centre study. ANIMALS: A sample of 1226 horses that underwent general anaesthesia between June 2017 and June 2021. METHODS: Horses and ponies weighing > 200 kg, aged > 6 months, anaesthetized using a xylazine- or medetomidine-isoflurane balanced anaesthesia protocol and presenting a complete anaesthetic record were included. Data were extracted from the clinic record system and from the original anaesthesia records. Recoveries were divided into 'good' and 'bad' based on the available recovery scores. Influence of hypoxaemia [PaO2 < 60 mmHg (7.99 kPa)], hypotension (mean arterial pressure < 70 mmHg for at least 15 minutes) and hypercapnia [PaCO2 > 60 mmHg (7.99 kPa)], anaesthesia protocol, body weight, age, breed, sex, American Society of Anesthesiologists status, type of procedure, emergency or nonemergency, duration of anaesthesia, positioning, times spent in lateral and sternal recumbency during recovery, time until standing and nonassisted or assisted recovery on the assigned recovery score (good/bad) were investigated using generalized linear regression analysis (p < 0.05). RESULTS: Hypoxaemia and prolonged duration of anaesthesia were significantly associated with a bad recovery score. No other factors had a significant influence on recovery quality. CONCLUSION AND CLINICAL RELEVANCE: Hypoxaemia and prolonged anaesthesia duration have a negative effect on quality of anaesthetic recovery in horses. Clinically, this highlights the importance of keeping anaesthetic time as short as possible and to monitor oxygenation and treat hypoxaemia as soon as possible.

Adrenalectomy for the treatment of hypotension in a cat with phaeochromocytoma associated with caudal vena cava syndrome.

An 11-year-old spayed female, Persian cat was referred to the Jeonbuk Animal Medical Center for evaluation of a 2-month history of lethargy and anorexia. Physical examination revealed tachycardia and hypotension. Abdominal imaging via sonography and CT identified a right adrenal gland mass causing severe deviation and compression of the caudal vena cava. After stabilising the blood pressure and heart rate through positive inotropes and fluid therapy, right adrenalectomy was performed. Surgery confirmed the adrenal gland mass was severely compressing the caudal vena cava. Histopathological examination revealed that the mass was a pheochromocytoma. After adrenalectomy, blood pressure and heart rate stabilised and remained unaffected 8 months postsurgery. This report describes a rare case of an adrenal pheochromocytoma leading to caudal vena cava compression in a cat presenting with hypotension.

Evaluation of the agreement between lingual and thoracic limb noninvasive blood pressure with invasive blood pressure measurements in anaesthetized horses.

OBJECTIVE: To evaluate the agreement between noninvasive arterial blood pressure (NIBP) measured from the tongue and thoracic limb with invasive blood pressure (IBP), and to compare NIBP measured from the tongue and thoracic limb in anaesthetized horses. STUDY DESIGN: Prospective clinical study. ANIMALS: A group of eight client-owned healthy horses anaesthetized for scheduled procedures, American Society of Anesthesiologists classification I-II, weighing (mean ± standard deviation) 498 ± 91 kg and aged 7.8 ± 6.75 years. METHODS: Animals were premedicated with intravenous (IV) romifidine (0.04-0.08 mg kg-1) and methadone (0.1 mg kg-1). General anaesthesia was induced IV with ketamine (2.5 mg kg-1) and midazolam (0.05 mg kg-1) and maintained with isoflurane. The facial artery was catheterized for IBP measurements. Systolic (SAP), mean (MAP) and diastolic (DAP) arterial pressures were recorded from the NIBPtongue, NIBPlimb and IBP every 20 minutes during the procedure. Agreement between NIBP and IBP was evaluated based on the American College of Veterinary Internal Medicine criteria and American Association for Medical Instrumentation criteria using the Bland-Altman method. RESULTS: The mean bias and precision between IBP and NIBP measured from the tongue met the standards for all pressure ranges (< 10 mmHg and < 15 mmHg, respectively). NIBP measurements from the tongue and thoracic limb tended to underestimate IBP measurements. During hypotension, MAPtongue and DAPtongue overestimated IBP, but both precision and accuracy met the criteria. The overall accuracy and precision of NIBPlimb was poorer than NIBPtongue. The percentage of NIBPtongue that differed from IBP by < 10 mmHg was higher than that recorded with NIBPlimb for SAP (46% versus 25%), MAP (77% versus 28%) and DAP (79% versus 19%). CONCLUSIONS AND CLINICAL RELEVANCE: The tongue is a clinically suitable alternative for assessing arterial blood pressure compared with the thoracic limb and can reliably detect hypotension in healthy anaesthetized horses.

Intranasal dexmedetomidine as premedication for magnetic resonance imaging examinations in dogs with neurological disorders mitigates hypotension and hypothermia.

OBJECTIVE: This study aimed to evaluate the safety and feasibility of intranasal administration of dexmedetomidine as a premedication for preventing hypotension and hypothermia in canine patients undergoing MRI examinations. ANIMALS: Dogs undergoing MRI examinations for neurological disorders were enrolled in this study. The dogs were randomly assigned: 15 to the N-Dex group (without premedication) and 13 to the Dex group (125 µg/m2 of dexmedetomidine, intranasally, as a premedication). METHODS: During the examination, pulse rate, systolic blood pressure, diastolic blood pressure, and mean arterial blood pressure were recorded every 5 minutes for the first 30 minutes. Body temperature was measured before and after the examination. Any adverse events during the procedure were documented. RESULTS: Significant changes in pulse rate during the examination were not distinguishable. Although blood pressure and body temperature decreased in both groups under anesthesia, dogs in the Dex group had a significantly smaller drop in blood pressure and body temperature and fewer hypotension events than those in the N-Dex group MRI examinations of 1 hour's duration. Two dogs in the Dex group exhibited bradycardia at 45 and 60 minutes of MRI examination, which resolved after receiving atipamezole. CLINICAL RELEVANCE: Our results indicate that intranasal administration of 125 µg/m2 of dexmedetomidine as premedication is safe and can potentially mitigate hypothermia and hypotension in dogs with neurological disorders during MRI examinations.

Increasing age and severe intraoperative hypotension associated with nonsurvival in dogs with gallbladder mucocele undergoing cholecystectomy.

OBJECTIVE: To identify prognostic indicators and inflammatory markers associated with nonsurvival in dogs with gallbladder mucoceles (GBMs) following cholecystectomy and to evaluate C-reactive protein (CRP) and haptoglobin concentrations in dogs with GBMs compared to healthy controls. ANIMALS: 25 dogs that underwent cholecystectomy for removal of GBM and 20 healthy control dogs. METHODS: A prospective, multicenter cohort study. Survival outcomes to hospital discharge and 2 weeks postdischarge were recorded from medical records. Laboratory variables, inflammatory markers (CRP and haptoglobin), and 25-hydroxyvitamin(OH) D (25[OH]D) concentrations were measured preoperatively. Associations between signalment, clinicopathologic variables, acute patient physiologic and laboratory evaluation (APPLEFAST) scores, inflammatory markers, 25(OH)D concentration, and survival were analyzed using logistic regression. RESULTS: 76% (19/25) and 68% (17/25) of dogs survived to hospital discharge and 2 weeks postdischarge, respectively. For each additional year of age, the odds of nonsurvival in hospital and 2 weeks postdischarge increased by 2.2 (P = .01; 95% CI, 1.2 to 5.0) and 1.7 (P = .04; 95% CI, 1.0 to 3.2), respectively. Intraoperative systolic blood pressure ≤ 65 mm Hg increased the probability of nonsurvival in hospital (P < .04). Gallbladder perforation, APPLEFAST scores, and preoperative serum concentrations of CRP, haptoglobin, and 25(OH)D were not associated with survival. Serum CRP and haptoglobin concentrations were greater in dogs with GBM compared to controls (P < .001). CLINICAL RELEVANCE: Increasing age and intraoperative systolic blood pressure ≤ 65 mm Hg were associated with nonsurvival in dogs with GBM undergoing cholecystectomy. Serum CRP, haptoglobin, and 25(OH)D were not associated with nonsurvival postcholecystectomy in this sample population.

Association between body mass and hypotension in dogs under general anaesthesia.

OBJECTIVES: To investigate the association between body mass and hypotension during general anaesthesia in dogs undergoing surgical and diagnostic procedures within a referral hospital. MATERIALS AND METHODS: Retrospective evaluation of the anaesthetic records of 1789 dogs was performed. Data on signalment, anaesthetic protocol and physiological variables, including mean arterial pressure, were collected. A multivariable generalised linear model was used to identify associations between explanatory variables, including body mass, and hypotension. RESULTS: In the population studied, increasing body mass (per 10 kg) was significantly associated with decreasing odds of hypotension (odds ratio 0.68; 95% confidence interval: 0.60 to 0.77). Additional variables associated with a decreased odds of hypotension were pre-anaesthetic medication with alpha-2 agonists (odds ratio 0.63; 95% confidence interval 0.48 to 0.82) and increased body temperature (per 1°C) during general anaesthesia (odds ratio 0.77; 95% confidence interval 0.67 to 0.88). Brachycephaly (odds ratio 1.72; 95% confidence interval 1.25 to 2.38), ASA physical status classification >3 (odds ratio 2.03; 95% confidence interval 1.16 to 3.56), undergoing a surgical procedure (versus diagnostic) (odds ratio 1.57; 95% confidence interval 1.10 to 2.23) and bradycardia (odds ratio 1.37; 95% confidence interval 1.05 to 1.80) were independently associated with increased odds of hypotension. CLINICAL SIGNIFICANCE: Dogs of lower body mass and brachycephalic breeds may be at higher risk of hypotension during general anaesthesia or alternatively represent subpopulations in which accurate blood pressure measurement presents a greater challenge. Monitoring blood pressure accurately in these groups requires particular attention and provisions for treating hypotension should be readily accessible.

Cardiac output affects the response to pulsed inhaled nitric oxide in mechanically ventilated anesthetized ponies determined by CT angiography of the lung.

OBJECTIVE: To measure changes in regional lung perfusion using CT angiography in mechanically ventilated, anesthetized ponies administered pulsed inhaled nitric oxide (PiNO) during hypotension and normotension. ANIMALS: 6 ponies for anesthetic 1 and 5 ponies for anesthetic 2. PROCEDURES: Ponies were anesthetized on 2 separate occasions, mechanically ventilated, and placed in dorsal recumbency within the CT gantry. Pulmonary arterial, right atrial, and facial arterial catheters were placed. During both anesthetics, PiNO was delivered for 60 minutes and then discontinued. Anesthetic 1: hypotension (mean arterial pressure < 70 mmHg) was treated using dobutamine after 30 minutes of PiNO delivery. Following the discontinuation of PiNO, dobutamine administration was discontinued in 3 ponies and was continued in 3 ponies. The lung was imaged at 30, 60, and 105 minutes. Anesthetic 2: hypotension persisted throughout anesthesia. The lung was imaged at 30, 60, and 90 minutes. At all time points, arterial and mixed venous blood samples were analyzed and cardiac output (Q˙t) was measured. Pulmonary perfusion was calculated from CT image analysis. RESULTS: During PiNO delivery, perfusion to well-ventilated lungs increased if ponies were normotensive, leading to increased arterial oxygenation, reduced alveolar dead space, and reduced alveolar to arterial oxygen tension gradient. When PiNO was stopped and dobutamine administration continued, alveolar dead space and venous admixture increased, in contrast to when dobutamine and PiNO were both discontinued. CLINICAL RELEVANCE: If PiNO is administered to mechanically ventilated, anesthetized ponies with concurrent hypotension and low Q˙t, this must be supported to achieve favorable redistribution of pulmonary perfusion to improve pulmonary gas exchange.

Low-dose epidural anesthesia decreases the use of intraoperative systemic analgesics in goats undergoing lower urinary tract surgery.

OBJECTIVE: To test whether the use of low-dose epidural anesthesia (EA) in goats undergoing lower urinary tract surgery reduces the requirements of perioperative analgesics, contributes to intraoperative hypotension, and improves postoperative comfort during the first 24 hours after surgery. ANIMALS: Retrospective analysis of 38 goats between January 2019 and July 2022. PROCEDURES: Goats were divided into 2 groups (EA or no EA). Demographic characteristics, surgical procedure, time of anesthesia, and anesthetic agents used were compared between treatment groups. Outcome variables potentially related to the use of EA included dose of inhalational anesthetics, incidence of hypotension (mean arterial pressure < 60 mm Hg), intraoperative and postoperative administration of morphine, and time to first meal after surgery. RESULTS: EA (n = 21) consisted of bupivacaine or ropivacaine 0.1% to 0.2% with an opioid. There were no differences between groups except for age (EA group was younger). Less inhalational anesthetic (P = .03) and less intraoperative morphine (P = .008) were used in the EA group. The incidence of hypotension was 52% for EA and 58% for no EA (P = .691). Administration of postoperative morphine was not different between groups (EA, 67%, and no EA, 53%; P = .686). Time to first meal was 7.5 hours (3 to 18 hours) for EA and 11 hours (2 to 24 hours) for no EA (P = .057). CLINICAL RELEVANCE: Low-dose EA reduced the use of intraoperative anesthetics/analgesics in goats undergoing lower urinary tract surgery without an increased incidence of hypotension. Postoperative morphine administration was not reduced.

Evaluation of urine specific gravity as a predictor of hypotension during anaesthesia in healthy dogs premedicated with dexmedetomidine.

OBJECTIVE: To investigate the relationship between urine specific gravity (USG) and the risk of arterial hypotension during general anaesthesia (GA) in healthy dogs premedicated with dexmedetomidine and methadone. STUDY DESIGN: Prospective clinical cohort study. ANIMALS: A total of 75 healthy client-owned dogs undergoing GA for elective tibial plateau levelling osteotomy. METHODS: After placing an intravenous catheter, dogs were premedicated with dexmedetomidine (5 µg kg-1) and methadone (0.3 mg kg-1) intravenously. After induction of GA with alfaxalone to effect, the bladder was expressed and USG measured. An arterial catheter was placed, and residual blood was used to measure packed cell volume (PCV) and total protein (TP). GA was maintained with isoflurane vaporised in oxygen and a femoral and sciatic nerve block were performed. Arterial blood pressure < 60 mmHg was defined as hypotension and recorded by the anaesthetist. Treatment for hypotension was performed in a stepwise manner following a flow chart. Frequency of hypotension, treatment and response to treatment were recorded. Logistic regression modelling was used to assess the association between USG, TP and PCV and incidence of perioperative hypotension; p < 0.05. RESULTS: Data from 14 dogs were excluded. Of the 61 dogs, 16 (26%) were hypotensive during GA, 15 dogs needed treatment of which 12 were responsive to a decrease in inhalant vaporiser setting. The logistic regression model was not statistically significant (p = 0.8). There was no significant association between USG (p = 0.6), TP (p = 0.4), PCV (p = 0.8) and arterial hypotension during GA. CONCLUSIONS AND CLINICAL RELEVANCE: In healthy dogs premedicated with dexmedetomidine and methadone and maintained under GA with isoflurane and a femoral and sciatic nerve block, there was no relationship between the specific gravity of urine collected after premedication and intraoperative arterial hypotension.

Cuff size, cuff placement, blood pressure state, and monitoring technique can influence indirect arterial blood pressure monitoring in anesthetized bats (Pteropus vampyrus).

OBJECTIVE: Evaluate agreement between 2 non-invasive blood pressure (NIBP) techniques and invasive arterial blood pressure (IBP) in anesthetized bats using various cuff sizes and cuff positioning while also evaluating its performance during hypertension and hypotension. ANIMALS: 8 bats (1.1 ± 0.2 kg). PROCEDURES: Bats were anesthetized with isoflurane in oxygen. NIBP was measured using oscillometric (NIBP-O) and Doppler (NIBP-D) techniques in the pectoral limb (PEC) and pelvic limbs (PEL) using 3 cuff sizes (1, 2, and 3). NIBP measurements were compared with IBP; systolic (SAPinvasive), mean (MAPinvasive), and diastolic arterial blood pressure (DAPinvasive) during normotension, hypertension, and hypotension. Hypotension was induced with isoflurane (3.8 ± 1.2%) and hypertension with norepinephrine (3 ± 0.5 µg/kg/min). Data analysis included Bland-Altman analyses and 3-way ANOVA. Results were reported as mean bias (95% CI). RESULTS: NIBP-O monitor reported 29% errors, and experienced more failures with hypertension, cuff placement on PEC, and using a size 1 cuff. Across states, an agreement between NIBP-D and MAPinvasive with cuff 2 on PEL (-3 mmHg [-8, 1]), and NIBP-D and SAPinvasive with cuff 3 on PEC (2 mmHg [-5, 9 mmHg]) was achieved. NIBP-D over-estimated SAPinvasive and MAPinvasive during hypertension in both limbs with cuffs 1 and 2. Except during hypotension, NIBP-O underestimated MAPinvasive and DAPinvasive using a size 2 cuff on PEL. CLINICAL RELEVANCE: In anesthetized bats, NIBP-O is unreliable for estimating IBP. NIBP-D shows acceptable agreement with MAPinvasive with cuff size 2 on PEL, and with SAPinvasive with cuff size 3 on PEC across a wide range of IBP values.

Ultrafiltration during intermittent hemodialysis in dogs with acute kidney injury.

BACKGROUND: Ultrafiltration is performed to alleviate fluid overload in dogs with acute kidney injury (AKI) undergoing intermittent hemodialysis (IHD). OBJECTIVES: To describe prescription patterns for ultrafiltration in dogs receiving IHD for AKI and risk factors for ultrafiltration-related complications. ANIMALS: Seventy-seven dogs undergoing 144 IHD treatments between 2009 and 2019. METHODS: Medical records of dogs receiving IHD for AKI were reviewed. The initial 3 IHD treatments in which ultrafiltration was prescribed were included. Ultrafiltration-related complications were defined as those requiring an intervention such as transient or permanent discontinuation of ultrafiltration. RESULTS: Mean fluid removal rate per treatment was 8.1 ± 4.5 mL/kg/h. Ultrafiltration-related complications occurred in 37/144 (25.7%) of treatments. Hypotension was rare (6/144, 4.2% of treatments). No ultrafiltration-related complications resulted in deaths. The mean prescribed fluid removal rate per treatment was higher in dogs with ultrafiltration-related complications than without (10.8 ± 4.9 mL/kg/h vs 8.8 ± 5.1 mL/kg/h, respectively; P = .03). The mean delivered fluid removal rate per treatment was significantly lower in dogs with UF-related complications compared to those without complications (6.8 ± 4.0 mL/kg/h vs 8.6 ± 4.6 mL/kg/h, respectively; P = .04). Variables associated with ultrafiltration-related complications (P < .05) included central venous oxygen saturation, body temperature before IHD treatment, total extracorporeal circuit volume and BUN at the end of IHD treatment. CONCLUSIONS AND CLINICAL IMPORTANCE: Ultrafiltration during IHD in dogs with AKI is overall safe. Higher prescribed ultrafiltration rates were associated with increased risk of complications. Decrease in central venous oxygen saturation is associated with ultrafiltration-related complications, emphasizing the utility of in-line blood monitoring.

Comparison between continuous rate infusion and target-controlled infusion of propofol in dogs: a randomized clinical trial.

OBJECTIVE: To compare a propofol continuous rate infusion (CRI) with a target-controlled infusion (TCI) in dogs. STUDY DESIGN: Randomized prospective double-blinded clinical study. ANIMALS: A total of 38 healthy client-owned dogs. METHODS: Dogs premedicated intramuscularly with acepromazine (0.03 mg kg-1) and an opioid (pethidine 3 mg kg-1, morphine 0.2 mg kg-1 or methadone 0.2 mg kg-1) were allocated to P-CRI group (propofol 4 mg kg-1 intravenously followed by CRI at 0.2 mg kg-1 minute-1), or P-TCI group [propofol predicted plasma concentration (Cp) of 3.5 µg mL-1 for induction and maintenance of anaesthesia via TCI]. Plane of anaesthesia, heart rate, respiratory rate, invasive blood pressure, oxygen haemoglobin saturation, end-tidal carbon dioxide and body temperature were monitored by an anaesthetist blinded to the group. Numerical data were analysed by unpaired t test or Mann-Whitney U test, one-way analysis of variance and Dunnett's post hoc test. Categorical data were analysed with Fisher's exact test. Significance was set for p < 0.005. RESULTS: Overall, propofol induced a significant incidence of relative hypotension (mean arterial pressure 20% below baseline, 45%), apnoea (71%) and haemoglobin desaturation (65%) at induction of anaesthesia, with a higher incidence of hypotension and apnoea in the P-CRI than P-TCI group (68% versus 21%, p = 0.008; 84% versus 58%, p = 0.0151, respectively). Propofol Cp was significantly higher at intubation in the P-CRI than P-TCI group (4.83 versus 3.5 µg mL-1, p < 0.0001), but decreased during infusion, while Cp remained steady in the P-TCI group. Total propofol administered was similar between groups. CONCLUSIONS AND CLINICAL RELEVANCE: Both techniques provided a smooth induction of anaesthesia but caused a high incidence of side effects. Titration of anaesthesia with TCI caused fewer fluctuations in Cp and lower risk of hypotension compared with CRI.

Cardiovascular effects of dobutamine, norepinephrine and phenylephrine in isoflurane-anaesthetized dogs administered dexmedetomidine-vatinoxan.

OBJECTIVE: To determine whether dobutamine, norepinephrine or phenylephrine infusions alleviate hypotension in isoflurane-anaesthetized dogs administered dexmedetomidine with vatinoxan. STUDY DESIGN: Balanced, randomized crossover trial. ANIMALS: A total of eight healthy Beagle dogs. METHODS: Each dog was anaesthetized with isoflurane (end-tidal isoflurane 1.3%) and five treatments: dexmedetomidine hydrochloride (2.5 µg kg-1) bolus followed by 0.9% saline infusion (DEX-S); dexmedetomidine and vatinoxan hydrochloride (100 µg kg-1) bolus followed by an infusion of 0.9% saline (DEX-VAT-S), dobutamine (DEX-VAT-D), norepinephrine (DEX-VAT-N) or phenylephrine (DEX-VAT-P). The dexmedetomidine and vatinoxan boluses were administered at baseline (T0) and the treatment infusion was started after 15 minutes (T15) if mean arterial pressure (MAP) was < 90 mmHg. The treatment infusion rate was adjusted every 5 minutes as required. Systemic haemodynamics were recorded at T0 and 10 (T10) and 45 (T45) minutes. A repeated measures analysis of covariance model was used. RESULTS: Most dogs had a MAP < 70 mmHg at T0 before treatment. Treatments DEX-S and DEX-VAT all significantly increased MAP at T10, but systemic vascular resistance index (SVRI) was significantly higher and cardiac index (CI) lower after DEX-S than after DEX-VAT. CI did not significantly differ between DEX-S and DEX-VAT-S at T45, while SVRI remained higher with DEX-S. Normotension was achieved by all vasoactive infusions in every dog, whereas MAP was below baseline with DEX-VAT-S, and higher than baseline with DEX-S at T45. Median infusion rates were 3.75, 0.25 and 0.5 µg kg-1 minute-1 for dobutamine, norepinephrine and phenylephrine, respectively. Dobutamine and norepinephrine increased CI (mean ± standard deviation, 3.35 ± 0.70 and 3.97 ± 1.24 L minute-1 m-2, respectively) and decreased SVRI, whereas phenylephrine had the opposite effect (CI 2.13 ± 0.45 L minute-1 m-2). CONCLUSIONS AND CLINICAL RELEVANCE: Hypotension in isoflurane-anaesthetized dogs administered dexmedetomidine and vatinoxan can be treated with either dobutamine or norepinephrine.

Surgical treatment for left atrial rupture due to myxomatous mitral valve disease in three dogs: A case report.

INTRODUCTION: Myxomatous mitral valve degeneration (MMVD) is an acquired heart disease which sometimes result in pulmonary oedema and left atrial rupture. In previous reports, left atrial rupture has been non-surgically controlled and its prognosis investigated. There is, however, no report concerning surgically treated left atrial rupture with mitral valvuloplasty and follow-up results. OBJECTIVES: This report aimed to develop a surgical strategy for a case of left atrial rupture caused by MMVD. MATERIALS AND METHODS: Three dogs were presented at a private hospital for surgical treatment of MMVD. All three dogs had a previous history of left atrial rupture due to MMVD. The left atrium rapture was diagnosed from indicating that characteristics of the drained pericardial effusion consistent with blood. Mitral valvuloplasty was performed in all dogs using an extracorporeal circulation machine, and the surgical procedure was modified according to each case. In cases with severe adhesion between the pericardial and left atrial appendage, suturing of the left atrial appendage was performed strategically. Additionally, in cases with severe hypotension caused by left atrial rupture, cardiopulmonary bypass was started as soon as possible during the surgical procedure. DISCUSSION AND CONCLUSION: Since the haemodynamics of all dogs had improved, and the owner reported no cardiac-related clinical signs, all drugs were withdrawn 3 months after surgery. Since left atrial rupture due to MMVD can cause hypotension, cardiopulmonary bypass should be started as soon as possible during the surgical procedure to maintain the blood pressure and suturing of the left atrial appendage should be performed strategically.

Hypotonic induction of aquaporin5 expression in rat astrocytes through p38 MAPK pathway.

Brain oedema is a common pathological phenomenon following many diseases and may lead to severe secondary damage. Astrocytes are the most numerous cells in the brain. Five aquaporins (AQPs) have been found in mature astrocytes, which play crucial roles in water transportation. However, most studies have focused on AQP4 or AQP9 and whether another aquaporin such as AQP5 involved in brain oedema is unclear. Here, we addressed the issue that the expression pattern of AQP5 in rat astrocytes in vitro was altered in the hypotonic condition through some mitogen-activated protein kinases (MAPK) pathways. Primary astrocytes were randomly divided into the control group and the hypotonic group. Cell viability was evaluated by MTT test. Immunofluorescence, Western blotting and real-time PCR were used to detect the expression of AQP5. Western blotting was used to detect the variation of MAPK pathway. The present study demonstrated that incubation of astrocytes in the hypotonic medium produced an increase inAQP5 expression, and AQP5 peaked at 6-12 h after hypotension solution exposure. In addition, MAPK pathways were set in motion under hypotension, but not all branches. Only the p38 inhibitor can inhibit AQP5 expression in cultured astrocytes. AQP5 is directly related to the extracellular hypotonic stimuli in astrocytes, which could be regulated through the p38 MAPK pathway.

Use of vasopressors for treatment of vasodilatory hypotension in dogs and cats by Diplomates of the American College of Veterinary Emergency and Critical Care.

OBJECTIVE: To identify the most common practices of Diplomates of the American College of Veterinary Emergency and Critical Care (DACVECCs) as they relate to the recognition and treatment of hypotension in dogs and cats, particularly concerning the use of vasopressors in vasodilatory shock states. DESIGN: A survey regarding vasopressor use was sent to all active DACVECCs using the Veterinary Information Network. Questions focused on respondent characteristics, method of recognition of hypotension, triggers for initiation of vasopressor therapy, first- and second-line vasopressor choice, and methods of determining response to therapy. SUBJECTS: A total of 734 DACVECCs were invited to participate, and 203 Diplomates (27.7%) completed the survey. RESULTS: For both dogs and cats, the most common first-line vasopressor was norepinephrine (87.9% in dogs and 83.1% in cats). The most common second-choice vasopressor was vasopressin (44.2% in dogs and 39.0% in cats). Cutoff values for initiating vasopressor therapy varied between species and modality used for blood pressure measurement. In general, most DACVECCs chose to initiate vasopressor therapy at a Doppler blood pressure <90 mm Hg or a mean arterial pressure of <60 or <65 mm Hg when using oscillometric or direct arterial blood pressure measurements in dogs and cats. CONCLUSIONS: Most DACVECCs adhere to published human guidelines when choosing a first-line vasopressor. However, there is significant variability in blood pressure measurement technique, cutoffs for initiation of vasopressor use, and choice of second-line vasopressors.

Evaluation of pimobendan effect on sublingual microcirculation in an experimental pharmacology induced hypotension porcine model.

New therapeutic approaches are needed to simultaneously resuscitate macro- and microcirculation during circulatory shock. The aims of this study were to explore the microcirculatory and macrocirculatory effects of pimobendan, an inodilator with dual phosphodiesterase 3 inhibitor and calcium-sensitizing effects, in an experimental porcine model of pharmacologically induced hypotension associating vasoplegia and decreased cardiac output. Eight piglets were anesthetized and monitored for their hemodynamic parameters. Hypotension was induced by sevoflurane overdose until a mean arterial pressure between 40 and 45 mmHg was reached. A bolus of pimobendan (0.25 mg/kg) was administered intravenously thereafter. Sublingual microcirculation was evaluated using a Sidestream Dark Field imaging device. Hemodynamic and microcirculatory parameters were recorded at the baseline period (A), immediately before pimobendan administration (B) and after pimobendan administration (C). Induction of hypotension was associated with a decreased cardiac index and microcirculation alterations. Pimobendan administration was associated with a significant increase in heart rate, cardiac index and decrease in systemic vascular resistance index. A significant increase in proportion of perfused vessels for all vessels (+8%, [2; 14], P = 0.01) and small vessels (+8% [1; 14], P = 0.03), in microvascular flow index (+0.31 AU, [0.04; 0,58], P = 0.03) were noticed, as well as a decrease in heterogeneity index (-0.34 [-0.66; -0.03], P = 0.04) and De Backer score for all vessels (-1.04, [-1.82; -0.25], P = 0.02). In conclusion, in a simple model of pharmacologically induced hypotension, pimobendan was associated with an improvement in several microcirculatory parameters.