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- Author or Editor: Noboru Sasaki x
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OBJECTIVE To elucidate the relationship between acute volume overload and left atrial phasic function in healthy dogs.
ANIMALS 6 healthy Beagles.
PROCEDURES Dogs were anesthetized. A Swan-Ganz catheter was placed to measure mean pulmonary capillary wedge pressure (PCWP). Cardiac preload was increased by IV infusion with lactated Ringer solution at 150 mL/kg/h for 90 minutes. Transthoracic echocardiography was performed before (baseline) and at 15, 30, 45, 60, 75, and 90 minutes after volume loading began. At each echocardiographic assessment point, apical 4-chamber images were recorded and analyzed to derive time–left atrial area curves. Left atrial total (for reservoir function), passive (for conduit function), and active (for booster-pump function) fractional area changes were calculated from the curves.
RESULTS Volume overload resulted in a significant increase from baseline in PCWP from 15 to 90 minutes after volume loading began. All fractional area changes at 15 to 90 minutes were significantly increased from baseline. In multiple regression analysis, quadratic regression models were better fitted to the relationships between PCWP and each of the total and active fractional area changes than were linear regression models. A linear regression model was better fitted to the relationship between PCWP and passive fractional area change.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that left atrial phasic function assessed on the basis of left atrial phasic areas was enhanced during experimental cardiac volume loading in healthy dogs. The effect of volume load should be considered when evaluating left atrial phasic function by indices derived from left atrial phasic sizes.
To determine the effects of IV administration of pimobendan on hemodynamic indices and indices of left atrial (LA) longitudinal strain by speckle-tracking echocardiography in healthy dogs.
6 healthy Beagles.
After the dogs were anesthetized, the right heart was catheterized and 2-D conventional and speckle-tracking echocardiography were performed before and after IV administration of 0.15 mg of pimobendan/kg. Speckle-tracking echocardiography was performed to assess the 3 LA phasic functions through LA deformation (longitudinal strain and strain rate) and volumetric analyses.
Pimobendan significantly increased stroke volume and cardiac output and decreased systemic vascular resistance. Pimobendan significantly improved left ventricular function assessed by the Tei index and LA booster pump function assessed by LA longitudinal strain and change in fractional volume during atrial systole. Indices of LA reservoir and conduit function were unchanged.
CONCLUSIONS AND CLINICAL RELEVANCE
In healthy dogs, IV administration of pimobendan improved the indices of LA booster pump function but had no effect on the indices of LA reservoir and conduit functions. Further studies are needed to validate whether these results can be extrapolated to dogs with myxomatous mitral valve disease.
To investigate the association between changes in cerebral blood flow and electrographic epileptic seizure in dogs using transcranial Doppler ultrasonography (TCD).
6 healthy Beagle dogs.
Each dog was administered pentetrazol (1.5 mg/kg/min) or saline (0.9% NaCl) solution under general anesthesia with continuous infusion of propofol. Both pentetrazol and saline solution were administered to all 6 dogs, with at least 28 days interval between the experiments. Blood flow waveforms in the middle cerebral artery and the basilar artery were obtained using TCD at baseline, after pentetrazol administration, and after diazepam administration. TCD velocities, including peak systolic velocity, end-diastolic velocity, and mean velocity and resistance variables, were determined from the Doppler waveforms.
During ictal-phase of pentetrazol-induced seizures, the TCD velocities significantly increased in the basilar and middle cerebral arteries while TCD vascular resistance variables did not change in either artery. The TCD velocities significantly decreased after diazepam administration. Systemic parameters, such as the heart rate, mean arterial pressure, systemic vascular resistance, cardiac index, end-tidal carbon dioxide, oxygen saturation, and body temperature, did not change significantly during seizures.
This study showed that cerebral blood flow, as obtained from TCD velocities, increased by 130% during ictal-phase of pentetrazol-induced seizures in dogs. The elevated velocities returned to baseline after seizure suppression. Thus, TCD may be used to detect electrographic seizures during the treatment of status epilepticus in dogs, and further clinical studies clarifying the association between changes in cerebral blood flow and non-convulsive seizure cases are needed.
To investigate the activities of gelatinases (matrix metalloproteinase [MMP]-2 and MMP-9) and serine proteases in the colorectal mucosa of Miniature Dachshunds (MDs) with inflammatory colorectal polyps (ICRPs).
15 MDs with ICRPs and 5 dogs with non–ICRP-related large bowel diarrhea (controls).
Zymographic methods were used to evaluate the activities of MMP-2, MMP-9, latent forms of MMP-2 and MMP-9 (pro–MMP-2 and pro–MMP-9), and serine proteases in inflamed and noninflamed tissue samples from MDs with ICRPs and in noninflamed tissue samples from control dogs. The associations of serine protease activities with MMP-2 or MMP-9 activity were also analyzed.
Activities of pro–MMP-2 and pro–MMP-9 were detected in most tissue samples, regardless of the tissue type, whereas activities of MMP-2 and MMP-9 were not detected in control tissue samples. In the inflamed tissue samples from MDs with ICRPs, the activities of MMP-2, pro–MMP-9, and MMP-9 were significantly higher than those in the noninflamed tissue samples from those dogs. Serine protease activities were significantly higher in the inflamed and noninflamed tissue samples from MDs with ICRP, compared with findings for control tissue samples. A weak correlation was detected between serine protease activities and MMP-9 activity.
CONCLUSIONS AND CLINICAL RELEVANCE
Study results suggested that gelatinase and serine protease activities are upregulated in the colorectal mucosa of MDs with ICRPs, possibly contributing to the pathogenesis of this disease through the functions of these enzymes in degradation of extracellular matrix and promotion of inflammatory cell migration and inflammatory responses.
To assess liver and spleen stiffness in healthy dogs by use of a novel 2-D shear wave elastography (SWE) technique and to investigate the repeatability and reproducibility of the technique.
8 healthy adult Beagles.
2-D SWE was performed on each dog to assess liver and spleen stiffness. Repeatability (intraday variability) and reproducibility (interday variability) of 2-D SWE were investigated. For all 8 dogs, 2-D SWE was performed 3 times in 1 day (4-hour intervals) and on 3 separate days (1-week interval). Data were expressed as mean ± SD values for shear wave velocity and the Young modulus in the liver and spleen. Intraday and interday coefficients of variation were assessed for all variables.
Mean ± SD shear wave velocity obtained for the liver and spleen was 1.51 ± 0.08 m/s and 2.18 ± 0.27 m/s, respectively. Mean value for the Young modulus obtained for the liver and spleen was 6.93 ± 0.79 kPa and 14.66 ± 3.79 kPa, respectively. Elasticity values were significantly higher for the spleen than for the liver. Intraday and interday coefficients of variation for all variables were < 25% (range, 3.90% to 20.70%).
CONCLUSIONS AND CLINICAL RELEVANCE
2-D SWE was a feasible technique for assessing liver and spleen stiffness of healthy dogs. Future studies on the application of 2-D SWE for dogs with chronic hepatitis, cirrhosis, and portal hypertension are needed to evaluate the clinical applicability of 2-D SWE.
OBJECTIVE To determine the relationship between acute volume overload and echocardiographic indices of right ventricular (RV) function and dyssynchrony in healthy dogs.
ANIMALS 7 healthy Beagles.
PROCEDURES Right heart catheterization and echocardiography were performed in 7 healthy anesthetized Beagles at baseline and after induction of volume overload. Volume overload was induced by IV infusion of lactated Ringer solution (150 mL/kg/h for 90 minutes). Echocardiographic indices of RV function, including peak velocity of systolic tricuspid annular motion, tricuspid annulus plane systolic excursion, fractional area change, RV Tei index, RV longitudinal strain (RVLS), and systolic RV longitudinal strain rate (RVLSR), were obtained by use of speckle tracking echocardiography (STE). In addition, SD of the systolic shortening time of the right ventricle for the 6 segments (RV-SD6) was determined with STE.
RESULTS Volume overload significantly increased the RV end-diastolic pressure, compared with the baseline value. Echocardiographic indices of RV function, except for septal RVLSR, were significantly enhanced by volume overload. In contrast, RV-SD6 did not change with volume overload. Although echocardiographic indices of RV function, except for septal RVLSR, were correlated with RV end-diastolic pressure, RV-SD6 was not correlated.
CONCLUSIONS AND CLINICAL RELEVANCE Echocardiographic indices of RV function, including RVLS and RVLSR, were affected by acute short-term volume overload. Therefore, results for assessment of RV function by use of STE in dogs with clinical conditions associated with right-sided chronic volume overload, such as tricuspid and pulmonic regurgitation, should be interpreted with caution.
Objective—To examine the expression and distribution of tight junction (TJ) and adherens junction (AJ) proteins in canine duodenal and colonic mucosa.
Sample—Mucosa obtained from 4 healthy Beagles.
Procedures—Biopsy specimens of the duodenum and colon were obtained via endoscopy from 4 healthy dogs. The expression patterns and subcelluar localization of claudin-1, -2, -3, -4, -5, -7, and -8; E-cadherin; and β-catenin in the duodenum and colon were analyzed by use of immunoblotting and immunofluorescence microscopy.
Results—In the duodenum, there was clear expression of claudin-3 and -5, E-cadherin, and β-catenin proteins and weak expression of claudin-7 protein. In contrast, there was clear expression of claudin-2 and -3, E-cadherin, and β-catenin proteins and weak expression of claudin-5 and -7 proteins in the colon, as determined by use of immunoblotting. As determined by the use of immunofluorescence microscopy, the duodenum and colon had staining for claudin-3 and -5, E-cadherin, and β-catenin in the most apical region and staining for claudin-7 in the basolateral region. Staining for claudin-2 was also observed in the colon.
Conclusions and Clinical Relevance—Information was provided about the expression patterns of TJ and AJ proteins in the duodenum and colon of clinically normal dogs. These results may provide valuable information for use in evaluating the importance of these TJ and AJ proteins in the pathogenesis of inflammatory bowel disease in dogs.
Objective—To evaluate left atrial phasic function in healthy dogs by means of 2-D speckle tracking echocardiography with time-left atrial area curve analysis and to assess repeatability and reproducibility of obtained measurements.
Animals—6 healthy Beagles.
Procedures—Each dog underwent echocardiography twice on different days (3 nonconsecutive examinations/d). Images were analyzed with offline software; area of the left atrium was automatically calculated in each frame throughout the cardiac cycle to derive time-left atrial area curves. Variables used to assess left atrial phasic function (total, passive, and active emptying area and emptying fractions and mean active and total emptying rates) were calculated. Agreement between variables measured via speckle tracking echocardiography and a manual tracing method was assessed with modified Bland-Altman analysis. Within-day and between-day coefficients of variation were determined.
Results—Mean ± SD total, passive, and active emptying fractions of the left atrium were 49.8 ± 3.5%, 277 ± 4.0%, and 30.5 ± 4.3%, respectively. Mean ± SD total and active emptying rates were 16.0 ± 2.5 cm2/s and 25.1 ± 4.9 cm2/s, respectively. Within-day and between-day coefficients of variation were < 20% (range, 0.41% to 16.4%) for all variables except mean active emptying rate (between-day coefficient of variation, 29.2%). Agreement between variables measured via speckle tracking echocardiography and the manual tracing method was good, and differences between methods were nonsignificant.
Conclusions and Clinical Relevance—Evaluation of left atrial phasic function via speckle tracking echocardiography was feasible; repeatability and reproducibility of measurements were adequate in healthy dogs. Studies are needed to determine clinical applicability in canine patients.