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Copyright of Canadian Veterinary Journal / Revue Vétérinaire Canadienne is the property of Canadian Veterinary Medical Association and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Veterinary Dermatology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: Echocardiographic assessment of left ventricular (LV) size and function using area-based indices and volumetric estimates is not well established in horses., Objective: To report reference intervals and measurement variability for uni-, 2-, and 3-dimensional echocardiographic indices of LV size and systolic function in Warmblood horses and to provide proof of concept for allometric scaling of variables to body weight. Unidimensional indices were to be compared to area-based indices and LV volume estimates to establish their clinical use., Animals: Thirty healthy Warmblood horses and 70 Warmblood horses with a primary diagnosis of mitral regurgitation or aortic regurgitation., Methods: Echocardiographic indices of LV size and systolic function were measured using an existing echocardiography database. Weight-related variables were scaled to body weight (BWT). Reference intervals and measurement variability were calculated, the influence of valvular regurgitation on LV size and function was investigated and agreement between different variables for detection of reduced, normal, and increased LV size and systolic function was assessed., Results: Reference values for healthy Warmblood horses were reported. Measurement variability was sufficiently low for clinical use of all variables. Allometric scaling was effective to correct diastolic LV dimensions and cardiac output for differences in BWT. Various echocardiographic indices resulted in different conclusions regarding identification of LV enlargement and systolic dysfunction in healthy horses and horses with valvular regurgitation., Conclusions and Clinical Importance: Echocardiographic assessment of LV size and systolic function should include joint assessment of multiple uni- and multidimensional indices. Area-based or volumetric indices that reflect LV long-axis motion should be included., (© 2020 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals LLC on behalf of American College of Veterinary Internal Medicine.)

Background: Little is known about normal heart rate variability (HRV) in horses during exercise. It can be difficult to separate premature beats from normal beat-to-beat variation at higher heart rates., Objectives: The aim was to quantify HRV in healthy horses during a high-speed treadmill-standardized exercise test (HSET) and to compare with the HRV in horses observed to have arrhythmias during exercise., Animals: Thirteen healthy horses (Group H), 30 horses with arrhythmias (Group A), and 11 horses with poor performance but no observed arrhythmias (Group O)., Methods: Prospective, observational study. All horses performed a HSET with simultaneous electrocardiograph (ECG) recorded. The ECGs were corrected for artifacts, and arrhythmias noted. Percent instantaneous beat-to-beat cycle length variation (% R-R variation) was calculated, and HRV analyses were performed on trot, canter, and recovery segments., Results: Group H showed between -4.4 and +3.8% R-R variation during trot and between -6.1 and +5.4% R-R variation during the canter phase of the HSET. Group A had significantly larger maximum and 1st percentile R-R shortening and lengthening compared with Group H and Group O during the recovery phase where most arrhythmias were observed. During recovery, a cutoff of 6% maximum % R-R shortening predicted the presence of arrhythmia with 88% sensitivity and 97% specificity and likelihood ratio of 26., Conclusions and Clinical Importance: Healthy horses have little instantaneous R-R variation during exercise. If a cardiac cycle shortens more than 6% from the previous cycle during the recovery phase, this R-R interval is likely to represent an arrhythmic event., (© 2018 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Background and Aim of the Study: Bioengineered living autologous valves with remodeling and growth capacity represent a promising concept for future cardiac and venous valve repair. A meticulous understanding of the mechanisms involved in recellularization and remodeling is essential for the safe and efficient clinical translation of this technology. In this context, the first investigations of bioengineered vascular grafts in immune-incompetent or transgenic rodents represented an important step. However, the in-vivo assessment of bioengineered synthetic scaffold-based (biodegradable) valve replacements in rodent models has not been achieved to date., Methods: Miniaturized monocuspid PGA (polyglycolic acid)-P4HB (poly-4-hydroxybutyrate)-based valves were created, incorporated into metallic stents (length 2.0 mm, diameter 1.1 mm) and introduced into catheter-based implantation devices. Wistar outbred rats (n = 8) underwent a laparotomy, abdominal aorta arteriotomy and valve delivery into the abdominal aorta. Valve placement and function were evaluated following deployment using ultrasound (Doppler- and M-mode). Explanted tissues were analyzed both macroscopically and histopathologically., Results: No significant physiological or hemodynamic changes were observed, including heart rate, pressure gradients, velocity values and cardiac output before and after valve implantation. The cross-sectional area at the level of the stented valve was reduced by 22%. Valvular leaflet oscillation was observed in two animals, and thrombus formation in the stent was observed in one animal. Histological evaluation revealed cellular infiltration within 3 h in vivo, and no signs of thrombus deposition on the valvular surface., Conclusions: This study demonstrated the technical feasibility of the transcatheter implantation of bioengineered stented miniaturized valves into the infrarenal rat aorta, without affecting the animal's physiological and hemodynamic variables and with valvular oscillation in part of the implants. These results could serve as a basis for the implementation of a chronic rat in-vivo model for mechanistic studies in bioengineered valvular tissues under systemic hemodynamic conditions. Video 1: 2D ultrasonographic projection revealing graft's leaflet oscillation.

Objective: To evaluate the non-calibrated, minimally invasive cardiac output (CO) monitor FloTrac/Vigileo (FloTrac) against thermodilution (TD) CO in standing horses., Study Design: Prospective, experimental trial., Animals: Nine adult horses weighing a median (range) of 535 (470-602) kg., Methods: Catheters were placed in the right atrium, pulmonary artery and carotid artery under local anaesthesia. CO was measured 147 times by TD and FloTrac and indexed to body weight. Changes in CO were achieved with romifidine or xylazine and dobutamine constant rate infusions. Bland-Altman analysis, concordance and polar plot analysis were used to assess agreement and ability to track changes in CO., Results: Mean ± standard deviation COTD of 48 ± 16 mL kg(-1) minute(-1) (range: 19-93 mL kg(-1) minute(-1) ) and mean COF loTrac of 9 ± 3 mL kg(-1) minute(-1) (range: 5-21 mL kg(-1) minute(-1) ) were measured. Low agreement with a large mean bias of 39 mL kg(-1) minute(-1) and wide limits of agreement of 8-70 mL kg(-1) minute(-1) were found. The percentage error of 108% and precision of TD of ± 18% resulted in an estimated precision of FloTrac of ± 106%. Comparison of changes in COF loTrac with changes in COTD gave a concordance rate of 52% in the four-quadrant plot, and a mean polar angle of -11° with radial limits of agreement of ± 61 ° in the polar plot. Mean arterial pressure (MAP) and COF loTrac were positively correlated (r = 0.5, p < 0.0001). No correlation of MAP with COTD was observed., Conclusions and Clinical Relevance: The FloTrac system, originally designed for use in humans, neither measured absolute CO in standing horses accurately nor tracked relative changes in CO measured by TD correctly. The false dependence of COF loTrac on arterial blood pressure further discourages the use of this technique in horses., (© 2015 Association of Veterinary Anaesthetists and the American College of Veterinary Anesthesia and Analgesia.)

Five horses were presented for treatment of atrial fibrillation by transvenous electrical cardioversion (TVEC). A dexmedetomidine infusion was administered for sedation during positioning of the cardioversion catheters, and continued during general anesthesia. Shocks were applied until return to sinus rhythm. Dexmedetomidine infusion provided excellent conditions for TVEC catheter placement and procedure.

Objective: Plasma atrial/A-type natriuretic peptide concentration (CpANP) was measured in horses presenting with various heart diseases to assess its potential diagnostic value., Animals: Fifteen healthy horses (Group 1) and 60 horses with various heart diseases associated with normal chamber size and function (Group 2, n = 24), associated with abnormal left atrial (LA) size and/or function but normal left ventricle (LV) (Group 3, n = 19), or associated with both abnormal LA and LV size and/or function (Group 4, n = 17)., Methods: CpANP was measured by a commercially available radioimmunoassay. Echocardiographic measurements were compared between groups by one-way ANOVA and Holm-Sidak post-hoc test. Receiver operating characteristics (ROC) analyses were performed to identify the best cut-offs to distinguish between groups. Relations between echocardiographic measurements and biomarker concentrations were assessed with backward stepwise multiple linear regression., Results: CpANP increased from Group 1 to 4 and was significantly higher in horses with heart disease than in controls. CpANP was associated with maximum LA area and LV fractional area change. The ROC analyses showed good specificity but poor sensitivity to distinguish between healthy horses and horses with heart disease overall, and between healthy horses and horses with altered left-sided chamber dimensions and/or function., Conclusion: CpANP is increased in horses with heart disease associated with altered left-sided chamber dimensions and/or function. However, its diagnostic value is compromised by poor sensitivity., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Background: The DNA of equine papillomavirus type 2 (EcPV2) is consistently found in equine papillomas and squamous cell carcinomas, indicating a causal association of EcPV2 in the pathogenesis of these tumours; however, little is known about the prevalence of this virus., Hypothesis/objectives: The aim of this study was to determine the geno- and seroprevalence of EcPV2 in clinically healthy horses in Switzerland., Animals: Fifty horses presented to the equine department of the university clinic, displaying no skin or mucous membrane lesions or severe signs of other diseases, were sampled., Methods: Cytobrush samples from the penis or vulva and serum samples were collected. To determine the genoprevalence of EcPV2, DNA was extracted from cytobrush samples and tested for viral DNA with a PCR assay amplifying a 338 bp fragment of the E7/E1 region of the viral genome. Seroprevalence was tested using an enzyme-linked immunosorbent assay aimed to detect antibodies against the major capsid protein (L1) of EcPV2., Results: In five of 50 horses (10%), EcPV2-specific DNA was amplified but no antibodies could be detected, whereas in 14 of 50 horses (28%), antibodies against EcPV2 but no DNA were demonstrated. Both antibodies and viral DNA were detected in four of 50 horses (8%). Neither antibodies nor viral DNA were found in 27 of 50 horses (54%)., Conclusions and Clinical Importance: The seroprevalence suggests that EcPV2 is prevalent in the Swiss equine population, while the genoprevalence indicates that currently ongoing infections are less common. The discrepancy between geno- and seroprevalence probably indicates different stages of infection in the tested cohort., (© 2014 ESVD and ACVD.)

Objective: To evaluate the applicability and accuracy of a continuous glucose monitoring system (CGMS) in critically ill foals by comparing the performance of the CGMS, a point-of-care (POC) glucometer, and an in-house standard laboratory assay (SLA)., Design: Prospective study., Setting: University teaching hospital., Animals: Seven critically ill neonatal foals requiring intensive care., Interventions: Foals were instrumented with a CGMS that measured interstitial glucose concentration every 5 minutes for the duration of 15-79 hours. Capillary and venous blood samples were taken every 4-6 hours for POC and SLA measurements, respectively., Measurements and Main Results: Bland-Altman analysis showed a mean bias (95% limits of agreement) of -0.1 (-3.9 to 3.5) mmol/L for comparison of CGMS versus SLA, 0.06 (-3.9 to 4.0) mmol/L for comparison of CGMS versus POC glucometer, and -0.16 (-1.8 to 1.5) mmol/L for comparison of POC glucometer versus SLA. Percent agreement and weighted kappa for classification in hypoglycemia, normoglycemia, and hyperglycemia were 68.4% and 0.296 for CGMS versus SLA, 72.4% and 0.442 for CGMS versus POC glucometer, and 80.7% and 0.568 for POC glucometer versus SLA., Conclusions: The CGMS may be helpful for monitoring a trend in interstitial glucose concentration in critically ill neonatal foals. However, considering the wide limits of agreement between methods, the CGMS should only be used as an adjunctive device to other, more accurate and readily available methods that are able to detect acute changes in glucose concentration. Its use is further limited by the relatively high costs of the sensors, the mandatory 2-hour initialization period, and the difficulties of keeping the transducer in place in an active foal. The POC glucometer used in this study is easy to use and proved to be sufficiently accurate for repeated, stall-sided glucose monitoring in neonatal foals., (© Veterinary Emergency and Critical Care Society 2013.)

Objective: Atrial natriuretic peptide (ANP) and cardiac troponin I (cTnI) serve as biomarkers for increased cardiac pressure/volume loading and for myocardial stress or damage. The objective was to describe the time course of plasma ANP concentrations (CpANP) and plasma cTnI concentrations (CpcTnI) in horses with mitral regurgitation (MR) compared to healthy horses at rest and after exercise, and to describe the relationship of CpANP with cardiac dimensions and intracardiac pressures., Animals: 15 healthy Warmblood horses and 7 Warmblood horses with MR., Methods: Cardiac dimensions at rest were measured using echocardiography. All horses underwent standardized treadmill exercise. Biomarker concentrations and intracardiac pressures were measured at rest and after exercise. Hypotheses were tested using statistical methods. The level of significance was P < 0.05., Results: Horses with MR showed increased left atrial (LA) and left ventricular (LV) dimensions but similar exercise capacity compared to healthy horses. Pulmonary capillary wedge pressures (PCWP) and CpANP increased with exercise. Horses with MR had higher PCWP and higher CpANP at rest and after exercise compared to healthy horses, with the maximum difference in CpANP reached 10 min after exercise. CpANP was significantly related to PCWP and - although inconsistently and only in healthy horses - to echocardiographic indices of LA and LV size and function. CpcTnI was low throughout the study in both groups., Conclusions: CpANP is increased in horses with MR and is related to LA pressures and to left heart dimensions. MR is not necessarily associated with exercise intolerance and exercise-induced myocardial stress or damage., (Copyright © 2013 Elsevier B.V. All rights reserved.)

The objective of this study was to compare the cardiopulmonary effects of a xylazine or romifidine loading-dose, followed by a constant rate infusion (CRI) of the same α(2)-agonist. Nine research horses were treated in a randomized, blinded, crossover design with xylazine or romifidine. After instrumentation, a loading dose of intravenous xylazine (1mg/kg) or romifidine (80μg/kg) was administered, immediately followed by a CRI of xylazine (0.69mg/kg/h) or romifidine (30μg/kg/h) for a duration of 2h. Cardiopulmonary variables were recorded before bolus administration, during CRI, and for 1h after discontinuing drug administration. A significant decrease in haemoglobin concentration (tHb), arterial oxygen content (CaO(2)), oxygen delivery (D˙O(2)), mixed venous partial pressure of oxygen, heart rate, and cardiac output (Q˙t) followed the loading dose with both treatments. Carotid arterial blood pressure (ABP), systemic vascular resistance, and right atrial pressure (RAP) increased significantly. The increased ABP was followed by a significant decrease compared to baseline. Mean pulmonary arterial pressure increased significantly with romifidine only. No significant changes in stroke volume, arterial partial pressure of oxygen, and oxygen consumption were observed. Changes in Q˙t and RAP were more pronounced with romifidine. During CRI, tHb, and CaO(2) were significantly higher with romifidine, whereas D˙O(2) did not differ between treatments. Overall, cardiopulmonary effects were more pronounced and lasted longer with romifidine compared to xylazine. However, during CRI, there was no difference in D˙O(2) between drugs. With both α(2)-agonists, cardiovascular effects were most pronounced after loading dose administration and tended to stabilize during CRI., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Objectives: To investigate the relationship of heart rate (HR) and ECG time intervals to body weight (BWT) in healthy horses and ponies. We hypothesized that HR and ECG time intervals are related to BWT., Animals: 250 healthy horses of >30 breeds; 5.5 (1-30) y [median (range)]; 479 (46-1018) kg., Methods: Prospective study. Standard base-apex ECGs were recorded while the horses were standing quietly in a box stall. Mean HR over 15 s was calculated and RR interval, PQ interval, QRS duration, and QT interval were measured by a single observer.QT was corrected for differences in heart rate using Fridericia's formula (QT(cf) = QT/(3)√RR). The relationship between ECG variables and BWT, age, sex, and RR interval was assessed using multivariate backward stepwise regression analyses. Goodness of fit of the model was improved when using log(BWT) compared to BWT. Body weight was overall the strongest predictor of HR and ECG time intervals. Therefore, only log(BWT) was included as an independent variable in the final model. The level of significance was p = 0.05., Results: HR (R(2) = 0.21) showed a significant negative relationship and PQ (R(2) = 0.53), QRS (R(2) = 0.23), QT (R(2) = 0.14), and QT(cf) (R(2) = 0.02) showed significant positive relationships to log(BWT)., Conclusions: Small equine breeds undergoing routine ECG recordings have slightly faster heart rates and shorter ECG time intervals compared to larger equine breeds. Although the magnitude of absolute differences may be small, body weight needs to be considered among other factors when comparing HR and ECG time intervals to normal ranges in horses., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Objective: To study the applicability of anatomical M-mode (AMM) for assessment of left ventricular (LV) size and function in horses, evaluate agreement with conventional M-mode (CMM), determine reliability, and establish reference intervals for AMM measurements., Animals: 98 horses; 13.1 +/- 5.6 years; 538 +/- 78 kg., Methods: Two-dimensional and M-mode recordings were analyzed retrospectively. Standard LV dimensions and indices of LV function, including time intervals, were measured in CMM and compared with AMM studies in long-axis (lx) and short-axis (sx) views., Results: The percentages of measureable cycles were 99%, 97%, and 90% for routine LV studies in CMM(sx), AMM(sx), and AMM(lx) mode. For time intervals, >or= 93% of cycles could be measured using AMM compared to a maximum of 77% using CMM. AMM(sx) measurements agreed well with CMM(sx) measurements for LV studies; the agreement of AMM(lx) with CMM(sx) was markedly lower. The LV ejection time and the duration of electromechanical systole, but not the LV pre-ejection period and the index of myocardial performance, showed fair agreement between methods. Intraobserver and interobserver measurement variabilities were low for most variables., Conclusions: AMM can replace CMM for assessment of LV dimensions in horses, but is not recommended for measurement of time intervals., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)