Evaluation of Electrical Cardiometry for Measuring Cardiac Output and Derived Hemodynamic Variables in Comparison with Lithium Dilution in Anesthetized Dogs.

Numerous cardiac output (CO) technologies were developed to replace the 'gold standard' pulmonary artery thermodilution due to its invasiveness and the risks associated with it. Minimally invasive lithium dilution (LiD) shows excellent agreement with thermodilution and can be used as a reference standard in animals. This study evaluated CO via noninvasive electrical cardiometry (EC) and acquired hemodynamic variables against CO measured using LiD in six healthy, anesthetized dogs administered different treatments (dobutamine, esmolol, phenylephrine, and high-dose isoflurane) impacting CO values. These treatments were chosen to cause drastic variations in CO, so that fair comparisons between EC and LiD across a wide range of CO values (low, intermediate, and high) could be made. Statistical analysis included linear regression, Bland-Altman plots, Lin's concordance correlation coefficient (ρc), and polar plots. Values of p < 0.05 represented significance. Good agreement was observed between EC and LiD, but consistent underestimation was noted when the CO values were high. The good trending ability, ρc of 0.88, and low percentage error of ±31% signified EC's favorable performance. Other EC-acquired variables successfully tracked changes in CO measured using LiD. EC may be a pivotal hemodynamic tool for continuously monitoring circulatory changes, as well as guiding and treating cardiovascular anesthetic complications in clinical settings.

Transpulmonary ultrasound dilution is an acceptable technique for cardiac output measurement in anesthetized pigs.

OBJECTIVE: To evaluate cardiac output (CO) measurements using transpulmonary ultrasound (TPUD) technology and compare results with those of the gold standard, pulmonary arterial catheter thermodilution (PACTD), in 6 healthy anesthetized pigs during acute hemodynamic changes caused by manipulation of the blood volume. ANIMALS: 6 healthy male Landrace pigs. PROCEDURES: Over a period of 1 week, pigs were anesthetized with isoflurane, mechanically ventilated, and underwent instrumentation in dorsal recumbency. They were subjected to sequential experimental states during which the blood volume was manipulated so that the animals transitioned from normovolemia to hypovolemia (20% and 40% of blood volume depletion), back to normovolemia (autologous blood transfusion), and then to hypervolemia (following colloid bolus). During each volume state, CO measurements were compared between TPUD and PACTD. RESULTS: The mean ± SD relative bias between TPUD and PACTD was 7.71% ± 21.2% with limits of agreement -33.9% to 49.3%, indicating TPUD slightly underestimated CO values, compared with values obtained with PACTD. The mean ± SD of the bias between the 2 methods was 0.13 ± 0.5 L/min. Only 5 of 36 (13.9%) TPUD CO measurements had an absolute value of relative bias > 30%. The percentage error calculated for TPUD was 29.4%. CLINICAL RELEVANCE: Results suggested that TPUD measurements have acceptable agreement with PACTD measurements. Moreover, TPUD exhibits promising potential in being used interchangeably with PACTD for future hemodynamic research involving swine as species of interest.

The effect of erector spinae plane block on perioperative analgesic consumption and complications in dogs undergoing hemilaminectomy surgery: a retrospective cohort study.

OBJECTIVE: To compare the perioperative use of analgesics and complication rates in dogs administered an erector spinae plane (ESP) block or a traditional opioid-based (OP) treatment as part of analgesic management during hemilaminectomy. STUDY DESIGN: Retrospective cohort study. ANIMALS: Medical records of 114 client-owned dogs. METHODS: General data included demographics, duration of procedure, number of laminae fenestrated, perioperative use of steroid and non-steroidal anti-inflammatory drugs. Intra- and postoperative analgesics used in 48 hours and complications rates were compared between groups. Opioid use was expressed in morphine equivalents [ME (mg kg-1)]. Continuous data were compared using the Mann-Whitney U test and incidence of events with a Fisher's exact tests. Multiple linear regression was used to evaluate association between perioperative ME consumption (dependent variable) with other independent variables. Data are presented as median (range). Differences were considered significant when p < 0.05. RESULTS: Group ESP comprised 42 dogs and group OP 72 dogs. No differences were observed in the general data. Intraoperative ME was 0.65 (0.20-3.74) and 0.79 (0.19-5.60) mg kg-1 in groups ESP and OP, respectively (p = 0.03). Intraoperative infusion of lidocaine was administered intravenously (IV) to 23.8% and 68% of groups ESP and OP, respectively (p < 0.0001). Intraoperative infusion of ketamine was administered IV to 21% and 40% of groups ESP and OP, respectively (p = 0.04). Regression analysis revealed the ESP block as the only independent variable affecting the perioperative ME consumption. Pharmacological intervention to treat cardiovascular complications was administered to 21.4% and 47.2% of dogs in groups ESP and OP, respectively (p = 0.008). There were no differences in postoperative complication rates. CONCLUSIONS AND CLINICAL RELEVANCE: ESP block was associated with reduced perioperative opioid consumption, intraoperative adjuvant analgesic use and incidence of pharmacological interventions to treat cardiovascular complications in dogs undergoing hemilaminectomy.

Feasibility and efficacy of ultrasonographic and laparoscopic guidance for microwave ablation of clinically normal canine ovaries.

OBJECTIVE: To determine the optimal energy profile for and to assess the feasibility and efficacy of ultrasonographic and laparoscopic guidance for microwave ablation (MWA) of clinically normal canine ovaries. SAMPLE: 44 extirpated ovaries from 22 healthy dogs. PROCEDURES: In the first of 2 trials, 13 dogs underwent oophorectomy by routine laparotomy. Extirpated ovaries underwent MWA at 45 W for 60 (n = 11) or 90 (12) seconds; 3 ovaries did not undergo MWA and served as histologic controls. Ovaries were histologically evaluated for cell viability. Ovaries without viable cells were categorized as completely ablated. Histologic results were used to identify the optimal MWA protocol for use in the subsequent trial. In the second trial, the ovaries of 9 dogs underwent MWA at 45 W for 90 seconds in situ. Ultrasonographic guidance for MWA was deemed unfeasible after evaluation of 1 ovary. The remaining 17 ovaries underwent MWA with laparoscopic guidance, after which routine laparoscopic oophorectomy was performed. Completeness of ablation was histologically assessed for all ovaries. RESULTS: 2 ovaries were excluded from the trial 1 analysis because of equivocal cell viability. Six of 11 ovaries and 10 of 10 ovaries that underwent MWA for 60 and 90 seconds, respectively, were completely ablated. In trial 2, laparoscopic-guided MWA resulted in complete ablation for 12 of 17 ovaries. Dissection of the ovarian bursa for MWA probe placement facilitated complete ablation. CONCLUSIONS AND CLINICAL RELEVANCE: Laparoscopic-guided MWA at 45 W for 90 seconds was feasible, safe, and effective for complete ablation of clinically normal ovaries in dogs.

Comparison of intestinal leak pressure between cadaveric canine and commercial synthetic intestinal tissue that did and did not undergo enterotomy.

OBJECTIVE: To compare initial leak pressure (ILP) between cadaveric canine and synthetic small intestinal segments that did and did not undergo enterotomy. SAMPLE: Eight 8-cm grossly normal jejunal segments from 1 canine cadaver and eight 8-cm synthetic small intestinal segments. PROCEDURES: Intestinal segments were randomly assigned to undergo enterotomy (6 cadaveric and 6 synthetic segments) or serve as untreated controls (2 cadaveric and 2 synthetic segments). For segments designated for enterotomy, a 2-cm full-thickness incision was created along the antimesenteric border. The incision was closed in a single layer with 4-0 suture in a simple continuous pattern. Leak testing was performed with intestinal segments occluded at both ends and infused with dilute dye solution (999 mL/h) until the solution was observed leaking from the suture line or serosal tearing occurred. Intraluminal pressure was continuously monitored. The ILP at construct failure was compared between cadaveric and synthetic control segments and between cadaveric and synthetic enterotomy segments. RESULTS: Mean ± SD ILP did not differ significantly between cadaveric (345.11 ± 2.15 mm Hg) and synthetic (329.04 ± 24.69 mm Hg) control segments but was significantly greater for cadaveric enterotomy segments (60.77 ± 15.81 mm Hg), compared with synthetic enterotomy segments (15.03 ± 6.41 mm Hg). CONCLUSIONS AND CLINICAL RELEVANCE: Leak testing should not be used to assess the accuracy or security of enterotomy suture lines in synthetic intestinal tissue. Synthetic intestinal tissue is best used for students to gain confidence and proficiency in performing enterotomies before performing the procedure on live animals.

Description of ultrasound-guided quadratus lumborum block technique and evaluation of injectate spread in canine cadavers.

OBJECTIVE: To describe a quadratus lumborum (QL) block technique in canine cadavers and the spread of injectate. STUDY DESIGN: Prospective, randomized, descriptive, experimental anatomic study. ANIMALS: A group of 12 adult canine cadavers. METHODS: Gross and ultrasound anatomy of the sublumbar musculature and the relationship with the spinal nerves was studied in two cadavers. Bilateral ultrasound-guided injections were performed in eight cadavers in the fascial plane between the QL and psoas muscle using a dye-lidocaine solution [low volume (LV) 0.15 mL kg-1 or high volume (HV) 0.3 mL kg-1]. The ultrasound transducer was positioned caudal and parallel to the proximal aspect of the last rib, and an insulated needle was introduced in-plane using a ventrolateral to dorsomedial approach. Dissections were performed to determine the number of spinal nerves successfully stained (>1 cm) and the presence of injectate in the epidural space or abdominal cavity. Additionally, two cadavers were transversally cryosectioned after QL injection. RESULTS: Ventral branches of the last thoracic and first three lumbar spinal nerves ran between the bundles of the QL muscle and between the QL and psoas muscles. The target fascial plane was ultrasonographically identified and filled with the dye solution following all injections. Ventral branches of the thirteenth thoracic and first, second and third lumbar nerves were stained by 0.0%, 71.4%, 100%, 100%, and 25%, 100%, 100%, 100% using LV and HV, respectively. Multisegmental spread stained the lumbar sympathetic trunk on 0 (0-3) and 3 (0-4) vertebral levels with LV and HV, respectively. No abdominal or epidural spread was identified. CONCLUSION AND CLINICAL RELEVANCE: Although no significant differences were found, HV resulted in a higher percentage of stain on spinal nerves and sympathetic trunk than LV. Further studies are warranted to determine if the QL block provides somatic and visceral abdominal analgesia in dogs.

Initial leak pressures of four anastomosis techniques in cooled cadaveric canine jejunum.

OBJECTIVE: To compare the effectiveness of four different intestinal anastomosis techniques at preventing leakage after enterectomy. STUDY DESIGN: Experimental study. SAMPLE POPULATION: Grossly normal jejunal segments (N = 70) from three fresh canine cadavers. METHODS: Eight-centimeter cooled canine cadaveric jejunal segments were randomly assigned to a control group (six segments) and four treatment groups (16 segments each [two segments/anastomotic construct]): (1) handsewn anastomosis (HSA), (2) barbed suture anastomosis (B-HSA), (3) stapled functional end-to-end anastomosis (SFEEA), and (4) stapled functional end-to-end anastomosis with an oversew (SFEEA-O). Control segments and anastomotic constructs were infused intraluminally to the point of leakage. Initial leak pressures were recorded and compared. RESULTS: Initial leak pressures (median + range) for jejunal control segments, HSA, B-HSA, SFEEA, and SFEEA-O were 331.88 mmHg (range, 315.34-346.64), 35.17 (20.29-56.24), 24.99 (6.08-38.64), 28.77 (18.80-85.09), and 35.92 (12.05-80.71), respectively. No difference was detected between leak pressures of anastomosed segments (P = .35), all of which were more variable and lower than those of intact segments. CONCLUSION: No difference in initial leak pressures was detected between the four anastomosis techniques tested in cooled canine cadaveric jejunum. CLINICAL SIGNIFICANCE: All four anastomosis techniques evaluated in this study may be suitable in dogs.

Ultrasound-guided erector spinae plane block in canine cadavers: relevant anatomy and injectate distribution.

OBJECTIVE: To investigate the distribution and nerve staining of two volumes of lidocaine-dye solution after ultrasound-guided erector spinae plane (ESP) injections in canine cadavers. STUDY DESIGN: Experimental cadaveric study. ANIMALS: A total of nine canine cadavers. METHODS: ESP injections were performed between the longissimus thoracis muscle and the dorsolateral edge of the ninth thoracic transverse process. Two cadavers were transversally cryosectioned after unilateral ESP injections [0.6 mL kg-1; high volume (HV)]. In seven cadavers, bilateral ESP injections with HV or low volume (0.3 mL kg-1; LV) were performed. Gadodiamide was added to the injectate for two cadavers and magnetic resonance imaging (MRI) was performed pre- and post-injection. Injectate distribution and nerve staining of the branches of the spinal nerves were recorded after gross anatomical dissection. The thoracic paravertebral and epidural spaces were examined for dye solution. RESULTS: Cryosections, MRI and gross dissections showed that the injectate spread dorsally to the transverse processes, over the ventromedial aspect of the longissimus thoracis muscle where the medial and lateral branches of the dorsal branches of the spinal nerves are located. LV and HV stained a median (range) of 4 (2-7) and 4 (3-8) medial branches, respectively (p = 0.52). LV and HV stained 4 (2-5) and 5 (4-7) lateral branches (p = 0.26), respectively. Ventral branches were not stained, and dye was not identified in the epidural or paravertebral spaces. CONCLUSIONS: and clinical relevance Medial and lateral branches were consistently stained over several spinal segments. The number of nerves stained was not different with HV or LV, and the ventral branches of the spinal nerves were not stained in any cadaver. ESP block may find a clinical application to desensitize structures innervated by the medial and lateral branches of the dorsal branches of the thoracic spinal nerves.

Use of a modified passive leg-raising maneuver to predict fluid responsiveness during experimental induction and correction of hypovolemia in healthy isoflurane-anesthetized pigs.

OBJECTIVE To evaluate the use of a modified passive leg-raising maneuver (PLRM) to predict fluid responsiveness during experimental induction and correction of hypovolemia in isoflurane-anesthetized pigs. ANIMALS 6 healthy male Landrace pigs. PROCEDURES Pigs were anesthetized with isoflurane, positioned in dorsal recumbency, and instrumented. Following induction of a neuromuscular blockade, pigs were mechanically ventilated throughout 5 sequential experimental stages during which the blood volume was manipulated so that subjects transitioned from normovolemia (baseline) to hypovolemia (blood volume depletion, 20% and 40%), back to normovolemia, and then to hypervolemia. During each stage, hemodynamic variables were measured before and 3 minutes after a PLRM and 1 minute after the pelvic limbs were returned to their original position. The PLRM consisted of raising the pelvic limbs and caudal portion of the abdomen to a 15° angle relative to the horizontal plane. RESULTS Hemodynamic variables did not vary in response to the PLRM when pigs were normovolemic or hypervolemic. When pigs were hypovolemic, the PLRM resulted in a significant increase in cardiac output and decrease in plethysomographic variability index and pulse pressure variation. When the pelvic limbs were returned to their original position, cardiac output and pulse pressure variation rapidly returned to their pre-PLRM values, but the plethysomographic variability index did not. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested a modified PLRM might be useful for identification of hemodynamically unstable animals that are likely to respond to fluid therapy. Further research is necessary to validate the described PLRM for prediction of fluid responsiveness in clinically ill animals.

Effects of a single intravenous bolus injection of alfaxalone on canine splenic volume as determined by computed tomography.

The purpose of this study was to evaluate the effects of a single intravenous dose of alfaxalone on canine splenic volume. In 6 adult beagle dogs the splenic volume [mean ± standard error (SE)] was determined by computed tomography to be 0.17 ± 0.02 L before alfaxalone administration and 0.24 ± 0.02 L (P = 0.0091) and 0.23 ± 0.02 L (P = 0.0268) 15 and 30 min, respectively, after alfaxalone administration. Hematocrits (mean ± SE) obtained at the same times were, respectively, 46.3% ± 1.3%, 40.6% ± 1.3% (P = 0.0015), and 41.7% ± 1.3% (P = 0.0057). In conclusion, alfaxalone caused relaxation of the canine splenic capsule and an increase in the splenic volume, along with a decrease in the hematocrit in these dogs.

Le but de cette étude était d'évaluer les effets d'administration intraveineuse d'alfaxalone intraveineuse sur le volume splénique canin déterminé par la tomodensitométrie. Le volume de rate de 6 chiens beagle adultes a été déterminé par tomodensitométrie avant et après l'administration d'alfaxalone. Le volume splénique moyen (± erreur type) était 0,17 ± 0,02 L avant l'administration d'alfaxalone et 0,24 ± 0,02 L (P = 0,0091) et 0,23 ± 0,02 L (P = 0,0268) à 15 min et à 30 min après l'administration d'alfaxalone, respectivement. L'hématocrite moyen (± erreur type) était 46,3 % ± 1,3 % (SEM) avant l'administration d'alfaxalone et 40,6 % ± 1,3 % (P = 0,0015) et 41,7 % ± 1,3 % (P = 0,0057) à 15 min et à 30 min après l'injection. En conclusion, dans cette étude, l'alfaxalone a provoqué une relaxation de la capsule splénique canine et une augmentation de son volume avec une diminution de l'hématocrite.(Traduit par les auteurs).

Ultrasonographical identification of the superficial circumflex iliac artery as a landmark for location of the femoral nerve in dogs.

OBJECTIVE: To investigate the utility of identifying the superficial circumflex iliac artery (SCIA) via ultrasound as an anatomical landmark for ultrasound-guided femoral nerve block. STUDY DESIGN: Observational study. ANIMALS: A group of six canine cadavers weighing >20 kg. METHODS: Pelvic limbs from six canine cadavers were examined to study the relationship between the SCIA and the femoral nerve. Ultrasonographic imaging of the SCIA in each limb was obtained with the transducer placed transversely in the medial aspect of the pelvic limb at the inguinal area. Subsequently, a needle was inserted in close proximity to the femoral nerve using an in-plane technique based on the anatomical relationship between the SCIA and femoral nerve. A total of 0.1 mL of colored latex was then injected at the location where the femoral nerve was expected to be in relationship to the SCIA. Gross dissection of the inguinal region in each pelvic limb was performed after injection. Positive nerve location was defined when the colored latex was in contact with the femoral nerve. RESULTS: A total of eleven pelvic limbs were injected because the SCIA could not be successfully visualized in one limb. Upon dissection, colored latex was found to be in direct contact with the femoral nerve in all 11 injected limbs. CONCLUSIONS AND CLINICAL RELEVANCE: We concluded that the ultrasonographic visualization of the SCIA assisted in the accurate deposition of dye in proximity to the femoral nerve of canine cadavers. Further investigation will determine the efficacy of this technique for performing femoral nerve blocks.

Evaluation of the potential efficacy of an ultrasound-guided adductor canal block technique in dog cadavers.

OBJECTIVE: To evaluate an ultrasound-guided technique for adductor canal (AC) block by describing the distribution of methylene blue around the AC, popliteal fossa, saphenous, tibial and common fibular nerves in dog cadavers. STUDY DESIGN: Prospective experimental trial. ANIMALS: Ten mixed breed canine cadavers weighing 28.55 ± 3.94 kg. METHODS: Ultrasound scans of the AC were performed bilaterally in 10 canine cadavers. A high-frequency linear transducer was placed on the long axis of the pectineus muscle and using an in-plane technique, an insulated needle was introduced at a proximal to distal direction into the AC. Methylene blue 0.1% (0.3 mL kg-1) was administered followed by dissection. The presence of dye over the target nerves for ≥2 cm was considered successful distribution. Three of 10 cadavers were submitted to computed tomography (CT) and one of them to magnetic resonance (MR) evaluation. RESULTS: Methylene blue reached the AC in 20 (100%) and the popliteal fossa in 17 (85%) pelvic limbs. Staining was successful in the saphenous nerve (4.0 ± 1.57 cm) in 11 (55%) limbs, tibial nerve (2.65 ± 0.8 cm) in six (30%) and common fibular nerve (2.7 ± 0.9 cm) in four (20%). There was no evidence of staining around the motor branches of the femoral nerve. No intraneural or intravascular dye spread was found during dissections. Contrast distribution to the popliteal fossa was observed in three limbs (50%) in CT and in one (50%) MR image. CONCLUSIONS AND CLINICAL RELEVANCE: Although the tibial and common fibular nerves were not stained as often as the saphenous nerve, dye was encountered throughout the popliteal fossa near the nerves. The AC block may be useful for intra and postoperative analgesia in stifle surgery with minimal femoral motor dysfunction. However, further study is required to confirm its efficacy and safety in vivo.

Comparison of cardiac output measured by use of computed tomography and thermodilution in dogs.

OBJECTIVE To compare cardiac output (CO) measured by use of CT coronary angiography and thermodilution (criterion-referenced standard) at various CO values, record adverse effects, and determine the time needed to measure CO. ANIMALS 5 healthy purpose-bred Beagles (2 males and 3 females). PROCEDURES A prospective nonrandomized crossover study was conducted. Dogs were premedicated with butorphanol tartrate (0.2 mg•kg-1, IM). Anesthesia was induced by IV administration of etomidate (1 to 2 mg•kg-1) and midazolam (0.25 mg•kg-1). Orotracheal intubation was performed, and anesthesia was maintained by administration of isoflurane. The CO was determined by use of thermodilution and by use of CT at 3 CO values. Dobutamine was infused at various rates to obtain the 3 CO values. RESULTS 13 values were obtained and analyzed. The mean ± SD difference between methods was 0.09 ± 0.71 L•min-1 (95% confidence interval [CI], 0.52 to -0.34 L•min-1). Only 1 of 13 values was located on the 100% agreement line (ie, 0 line), 7 of 13 values were located within the 95% CI, and 5 of 13 values were outside the 95% CI. CONCLUSIONS AND CLINICAL RELEVANCE For this study, there was poor agreement between the 2 methods. The 95% CI interval was 0.52 to -0.34 L•min-1, and 5 of 13 values were outside the 95% CI. Therefore, results for the CT method appeared to be inappropriate for use in making clinical decisions.

Diagnostic usefulness of laparoscopy versus exploratory laparotomy for dogs with suspected gastrointestinal obstruction.

OBJECTIVE To evaluate the feasibility of laparoscopy versus exploratory laparotomy for the diagnosis of specific lesions in dogs with suspected gastrointestinal obstruction. DESIGN Controlled trial. ANIMALS 16 client-owned dogs with physical and radiographic findings consistent with gastrointestinal obstruction. PROCEDURES Single-incision laparoscopy with intracorporeal and extracorporeal examination of the gastrointestinal tract was performed by 1 surgeon. Immediately afterward, exploratory laparotomy was performed by a second surgeon. Accessibility and gross appearance of organs, surgical diagnoses, incision lengths, procedure duration, and complications were compared between diagnostic techniques. RESULTS Mean (95% confidence interval) incision length was 4.9 cm (3.9 to 5.9 cm) for laparoscopy and 16.4 cm (14.0 to 18.7 cm) for exploratory laparotomy. Mean (95% confidence interval) procedure duration was 36.8 minutes (31.6 to 41.2 minutes) and 12.8 minutes (11.4 to 14.3 minutes), respectively. Diagnoses of the cause of obstruction were the same with both methods. In 13 dogs, the laparoscopic examination was successfully completed, and in the other 3, it was incomplete. In 4 dogs in which laparoscopy was successful, conversion to exploratory laparotomy or considerable extension of the laparoscopic incision would have been required to allow subsequent surgical treatment of identified lesions. No dogs developed major complications, and minor complication rates were similar between procedures. CONCLUSIONS AND CLINICAL RELEVANCE Laparoscopy was feasible and clinically applicable in dogs with suspected gastrointestinal obstruction. Careful patient selection and liberal criteria for conversion to an open surgical approach are recommended when laparoscopy is considered for the diagnosis of gastrointestinal lesions in dogs.

Measurement of intraocular pressure in healthy anesthetized horses during hoisting.

OBJECTIVE: To measure intraocular pressure (IOP) in horses during hoisting after induction of anesthesia. STUDY DESIGN: Prospective nonrandomized clinical study. ANIMALS: Eighteen healthy adult horses aged [mean±standard deviation (SD)] 10±4.2 years and weighing 491±110 kg anesthetized for elective procedures. METHODS: IOP was measured in the superior eye of each horse based on planned recumbency after induction of anesthesia. Measurements were taken directly after premedication with xylazine or detomidine with butorphanol, after induction with diazepam-ketamine, after intubation, when suspended by the hoist and on the operating table. During hoisting, the head was supported and the eye-heart height was measured to account for variations in head positioning among patients. IOPs were compared across time points using repeated-measures analysis of variance. Regression was used to compare IOP outcome with potential cofactors. RESULTS: Compared with measurements after premedication (17.5±2.5 mmHg) (mean±SD), hoisting significantly increased IOP (32.4±15.3 mmHg) (p<0.01). The highest recorded IOP in the hoist was 80.0 (range, 16.0-80.0) mmHg. The difference in IOP between premedication and hoisting was 15.0±16.2 (range, -1.0 to 68.0) mmHg. Body weight had a significant effect on absolute IOP and change in IOP in the hoist (p<0.01). CONCLUSIONS AND CLINICAL RELEVANCE: Hoist IOP was significantly higher than post-premedication IOP with heavier horses having higher hoist IOPs and greater increases in IOP. The clinician should take this relationship into account when anesthetizing and hoisting larger horses where an increase in IOP could be detrimental.

Cardiac arrest in an American Cocker Spaniel during a deep ear flush procedure.

CASE DESCRIPTION A 14-year-old spayed female American Cocker Spaniel with bilateral otitis media and no evidence of cardiovascular instability was anesthetized to allow performance of a deep ear flush. CLINICAL FINDINGS Otoscopic examination of the left ear revealed evidence of chronic inflammation; the ear was flushed with sterile saline (0.9% NaCl) solution. Examination of the right ear revealed more severe chronic inflammation than in the left ear, including a ruptured tympanum (timing of rupture unknown). The right ear was flushed with sterile saline solution, and several drops of otic medication were instilled. During infusion of saline solution, the ECG revealed a rapid decrease in heart rate until no more electrical activity was noted. Pulse also ceased to be detectable via pulse oximetry and femoral artery palpation. TREATMENT AND OUTCOME Isoflurane was discontinued immediately after recognition of cardiac arrest. Shortly after, atropine (0.04 mg/kg [0.02 mg/lb]) and epinephrine (0.3 mg/kg [0.14 mg/lb]) were administered IV, chest compressions and ventilation were performed for 2 to 3 minutes, and 3 boluses (each 5 mL/kg) of lactated Ringer solution were administered IV. The dog was extubated 8 minutes after anesthesia was discontinued, and its recovery was monitored for the next 5 hours. No further incidents of cardiac arrest occurred after recovery from anesthesia. CLINICAL RELEVANCE This case represented a rarely documented potential complication associated with otic manipulation in a dog: cardiac arrest secondary to stimulation of the auricular branch of the vagus nerve. Veterinarians should be prepared for and warn clients of this possibility prior to otic flushing.

Eficácia e efeitos hemodinâmicos da anestesia raquidiana com ropivacaína isobárica, hipobárica ou hiperbárica em cães anestesiados com isofluorano / Efficacy and hemodynamic effects of spinal anesthesia with isobaric, hypobaric or hyperbaric ropivacaine in dogs anesthetized with isoflurane

O presente estudo objetivou avaliar a anestesia raquidiana com ropivacaína em cães alterando a baricidade do anestésico local, investigando as alterações hemodinâmicas e complicações. Foram utilizados seis cães, Beagle, 4 anos, submetidos a anestesia inalatória com isofluorano e aos tratamentos: Ghipo = anestesia raquidiana hipobárica (0,5 mL NaCl 0,9% + 0,5 mL ropivacaína 0,75%); Giso = anestesia raquidiana isobárica (0,5 mL NaCl 1,53% + 0,5 mL ropivacaína 0,75%); Ghiper = anestesia raquidiana hiperbárica (0,5 mL glicose 10% + 0,5 mL ropivacaína 0,75%). Após indução anestésica e manutenção com isofluorano, os animais foram posicionados em decúbito lateral direito para a passagem de um cateter de artéria pulmonar pela veia jugular esquerda. Após esse procedimento, a punção subaracnóide foi realizada entre L5-L6 com uma agulha espinhal 22G, seguida da administração de 1 mL de anestésico local em 1 min. Os animais foram mantidos por 60 minutos anestesiados em decúbito ventral. A FC, f, PAM, DC, PAPm e TºC apresentaram aumento progressivo em todos os grupos enquanto que a PCPm, apenas no GHIPO, aumentou ao longo de todos os momentos. O IRPT no GISO apresentou valores significativamente superiores no M1, M5 e M10 comparado aos demais grupos, exceto no M5, em que o GISO diferiu somente do GHIPER. O IRVP no GISO aumentou no M5 em comparação ao MB. Foram observados efeitos adversos como déficit motor unilateral, atonia vesical, excitação, dor aguda e quemose. De acordo com os dados obtidos no presente estudo pode-se concluir que os animais que receberam anestesia raquidiana com as soluções hiperbárica e isobárica apresentaram maior bloqueio motor comprovando que a baricidade influencia diretamente o tipo de fibra a ser bloqueada. A utilização de solução isobárica resulta em um bloqueio misto (motor e sensitivo). As alterações hemodinâmicas descritas na literatura como, bradicardia e hipotensão, não puderam ser evidenciadas neste estudo embora o volume de anestésico tenha sido baixo associado a influência dos efeitos do isofluorano. Em relação às complicações evidenciadas, sugere-se acompanhamento pós-anestésico dos animais submetidos à anestesia raquidiana a fim de que quaisquer alterações possam ser identificadas precocemente e tratadas.(AU)

The aim of the study was to assess hemodynamic changes and complications of spinal anesthesia with ropivacaine at different baricities. Six beagle dogs aged four years. The dogs were anesthetized with isoflurane and subjected to the following treatments: Ghypo = spinal anesthesia with hypobaric ropivacaine (0.5mL of 0.9% NaCl+0.5mL ropivacaine at 0.75%); Giso = isobaric spinal anesthesia (0.5mL of 0,906% NaCl+0.5mL ropivacaine at 0.75%); Ghyper = hyperbaric spinal anesthesia (0.5mL of 10% glucose+0.5mL ropivacaine at 0.75%). After induction to anesthesia and maintenance with isoflurane, animals were positioned in right lateral recumbency for pulmonary artery catheterization through the left jugular vein. Spinal anesthesia was carried out with injection of 1mL of local anesthetic using a 22G Quincke tip needle in the L5-L6 space along 1 minute. Dogs were maintained under inhalation anesthesia for 60 minutes in ventral recumbency. HR, FR, MAP, CO, mPAP and body temperature progressively increased in all groups, whereas PCWP increased only in GHYPO at all time points. The TPRI showed significantly higher values in GISO at M1, M5 and M10 compared to the other groups, except for M5, during which GISO differed only from GHYPER. The PVRI increased at M5 compared to MB in GISO. Side effects such as unilateral motor deficit, bladder atony, excitation, acute pain and chemosis were observed. The hemodynamic changes were not relevant, although inhalation anesthesia with isoflurane might have influenced the results. The changes observed in the study demonstrate that motor blockade is likely to be obtained with isobaric and hyperbaric ropivacaine, thereby confirming the influence of baricity on the type of nerve fibers on the spinal cord. The isobaric solution results in a mixed blockade (motor and sensory blockade). Hemodynamic changes such as hypotension and bradycardia were not evidenced in this study, although local anesthetics were administered in low volumes and together with isoflurane anesthesia. Regarding complications, post-anesthetic observation is warranted in order to identify and treat possible changes. Spinal anesthesia in the conditions studied did not cause hemodynamic changes in isoflurane-anesthetized dogs and is thus considered safe for routine practice, although a few complications are prone to occur.(AU)

Hypertension-Linked Pathophysiological Alterations in the Gut.

RATIONALE: Sympathetic nervous system control of inflammation plays a central role in hypertension. The gut receives significant sympathetic innervation, is densely populated with a diverse microbial ecosystem, and contains immune cells that greatly impact overall inflammatory homeostasis. Despite this uniqueness, little is known about the involvement of the gut in hypertension. OBJECTIVE: Test the hypothesis that increased sympathetic drive to the gut is associated with increased gut wall permeability, increased inflammatory status, and microbial dysbiosis and that these gut pathological changes are linked to hypertension. METHODS AND RESULTS: Gut epithelial integrity and wall pathology were examined in spontaneously hypertensive rat and chronic angiotensin II infusion rat models. The increase in blood pressure in spontaneously hypertensive rat was associated with gut pathology that included increased intestinal permeability and decreased tight junction proteins. These changes in gut pathology in hypertension were associated with alterations in microbial communities relevant in blood pressure control. We also observed enhanced gut-neuronal communication in hypertension originating from paraventricular nucleus of the hypothalamus and presenting as increased sympathetic drive to the gut. Finally, angiotensin-converting enzyme inhibition (captopril) normalized blood pressure and was associated with reversal of gut pathology. CONCLUSIONS: A dysfunctional sympathetic-gut communication is associated with gut pathology, dysbiosis, and inflammation and plays a key role in hypertension. Thus, targeting of gut microbiota by innovative probiotics, antibiotics, and fecal transplant, in combination with the current pharmacotherapy, may be a novel strategy for hypertension treatment.

Evaluation of epiduroscopy for detection of vertebral canal and spinal cord lesions in dogs.

OBJECTIVE To evaluate the potential usefulness of epiduroscopy for clinical diagnosis and treatment of vertebral canal and spinal cord lesions in dogs. SAMPLE Cadavers of 6 mixed-breed dogs. PROCEDURES Dogs were positioned in sternal recumbency, and an endoscope was introduced into the lumbosacral epidural space. A fiberscope (diameter, 0.9 mm; length, 30 cm) was used for 3 dogs, and a videoscope (diameter, 2.8 mm; length, 70 cm) was used for the other 3 dogs. Visibility and identities of anatomic structures were recorded, and maneuverability of the endoscopes was assessed. Extent of macroscopic tissue damage was evaluated by manual dissection of the vertebral canal at the end of the procedure. RESULTS Intermittent saline (0.9% NaCl) solution infusion, CO2 insufflation, and endoscope navigation improved visualization by separating the epidural fat from the anatomic structures of interest. Images obtained with the fiberscope were small and of poor quality, making identification of specific structures difficult. Maneuverability of the fiberscope was difficult, and target structures could not be reliably reached or identified. Maneuverability and image quality of the videoscope were superior, and spinal nerve roots, spinal dura mater, epidural fat, and blood vessels could be identified. Subsequent manual dissection of the vertebral canal revealed no gross damage in the spinal cord, nerve roots, or blood vessels. CONCLUSIONS AND CLINICAL RELEVANCE A 2.8-mm videoscope was successfully used to perform epiduroscopy through the lumbosacral space in canine cadavers. Additional refinement and evaluation of the technique in live dogs is necessary before its use can be recommended for clinical situations.

Temporary percutaneous T-fastener gastropexy and continuous decompressive gastrostomy in dogs with experimentally induced gastric dilatation.

OBJECTIVE To evaluate a percutaneous, continuous gastric decompression technique for dogs involving a temporary T-fastener gastropexy and self-retaining decompression catheter. ANIMALS 6 healthy male large-breed dogs. PROCEDURES Dogs were anesthetized and positioned in dorsal recumbency with slight left-lateral obliquity. The gastric lumen was insufflated endoscopically until tympany was evident. Three T-fasteners were placed percutaneously into the gastric lumen via the right lateral aspect of the abdomen, caudal to the 13th rib and lateral to the rectus abdominis muscle. Through the center of the T-fasteners, a 5F locking pigtail catheter was inserted into the gastric lumen and attached to a device measuring gas outflow and intragastric pressure. The stomach was insufflated to 23 mm Hg, air was allowed to passively drain from the catheter until intraluminal pressure reached 5 mm Hg for 3 cycles, and the catheter was removed. Dogs were hospitalized and monitored for 72 hours. RESULTS Mean ± SD catheter placement time was 3.3 ± 0.5 minutes. Mean intervals from catheter placement to a ≥ 50% decrease in intragastric pressure and to ≤ 6 mm Hg were 2.1 ± 1.3 minutes and 8.4 ± 5.1 minutes, respectively. After catheter removal, no gas or fluid leakage at the catheter site was visible laparoscopically or endoscopically. All dogs were clinically normal 72 hours after surgery. CONCLUSIONS AND CLINICAL RELEVANCE The described technique was performed rapidly and provided continuous gastric decompression with no evidence of postoperative leakage in healthy dogs. Investigation is warranted to evaluate its effectiveness in dogs with gastric dilatation-volvulus.