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In dogs, myocardial injury (MI) is a poorly characterized clinical entity; therefore, this study aimed to provide a detailed description of dogs affected by this condition. Dogs diagnosed with MI according to the concentration of cardiac troponin I (cTnI) were retrospectively searched. Signalment, diagnostic, therapeutic, and outcome data were retrieved. Dogs were divided into six echocardiographic (dilated cardiomyopathy phenotype; hypertrophic cardiomyopathy phenotype; hypertrophic cardiomyopathy phenotype with systolic dysfunction; abnormal echogenicity only; endocarditis; and no echocardiographic abnormalities suggestive of MI), four electrocardiographic (abnormalities of impulse formation; abnormalities of impulse conduction; abnormalities of ventricular repolarization; and no electrocardiographic abnormalities suggestive of MI), and nine etiological (infective; inflammatory; neoplastic; metabolic; toxic; nutritional; immune-mediated; traumatic/mechanical; and unknown) categories. Statistical analysis was performed to compare cTnI values among different categories and analyze survival. One hundred two dogs were included. The median cTnI value was 3.71 ng/mL (0.2–180 ng/mL). Echocardiographic and electrocardiographic abnormalities were documented in 86 of 102 and 89 of 102 dogs, respectively. Among echocardiographic and electrocardiographic categories, the dilated cardiomyopathy phenotype (n = 52) and abnormalities of impulse formation (n = 67) were overrepresented, respectively. Among dogs in which a suspected etiological trigger was identified (68/102), the infective category was overrepresented (n = 20). Among dogs belonging to different echocardiographic, electrocardiographic, and etiological categories, cTnI did not differ significantly. The median survival time was 603 days; only eight of 102 dogs died due to MI. Dogs with MI often have an identifiable suspected trigger, show various echocardiographic and electrocardiographic abnormalities, and frequently survive to MI-related complications. [ABSTRACT FROM AUTHOR]

Studies on the use of amiodarone or sotalol are limited in dogs. Therefore, this study aimed to provide data on the efficacy and safety of these drugs in dogs with ventricular tachyarrhythmia (VT) and/or supraventricular tachyarrhythmia (SvT). Dogs with VT and/or SvT treated with amiodarone or sotalol as a first-line therapy were retrospectively evaluated. Signalment, clinical, diagnostic, therapeutic, and outcome data were retrieved. For VT, efficacy was demonstrated through a decrease of the Lown-Wolf grade to less than five or a reduction of at least 85% in the number of ventricular premature complexes observed on Holter monitoring. For SvT, efficacy was represented by cardioversion or a reduction in the mean heart rate on Holter monitoring ≤140 beats/min. Treatment-related side effects (TRSEs) were classified as clinically relevant and irrelevant. Statistical analysis was performed to compare data before and after antiarrhythmic prescription. Sixty-four dogs were included. Amiodarone and sotalol were efficacious in treating both VT (85.7% and 90.0% of cases, respectively) and SvT (75% and 71.4% of cases, respectively). No significant differences were found when comparing their efficacy rates in dogs with VT and SvT (P=0.531 and 0.483, respectively). Clinically relevant TRSEs were rare with both amiodarone and sotalol (8.3% and 5% of cases, respectively), while clinically irrelevant TRSEs occurred more frequently with amiodarone (29.2%) than with sotalol (10%). In dogs with tachyarrhythmias, amiodarone and sotalol are generally efficacious and safe, as clinically relevant TRSEs seem rare. This study provides novel data on the effects of amiodarone and sotalol in dogs with tachyarrhythmias. [ABSTRACT FROM AUTHOR]

Left atrial tear (LAT) is a life-threatening complication in dogs with myxomatous mitral valve disease (MMVD). The study objective was to describe clinical presentation, echocardiographic findings, treatment strategies, and survival in dogs with LAT compared to a control group of dogs with a similar stage of MMVD but no LAT. Two-center retrospective case–controlled study including 15 dogs with and 15 dogs without LAT was conducted. Clinical and echocardiographic data were reviewed, and survival information were collected. Nine dogs in each group were in stage C of MMVD, while the remaining were in stage B2. No differences between groups were found regarding age, body weight, sex, kidney values, and echocardiography-derived cardiac dimensions. Most reported clinical signs associated with LAT included weakness, respiratory signs, and syncope. Treatment varied and was mainly focused on the management of congestive heart failure. Three dogs with LAT received a pericardiocentesis. All 15 dogs with LAT had died of cardiac causes, five dogs during the first seven days after admission. The median survival time for all 15 dogs with LAT was 52 days compared to 336 days in the control group (P=0.103). When excluding five dogs with LAT that died during the first seven days, the median survival increased to 407 days, not different compared to the control group (P=0.549). Dogs with MMVD and LAT have a high short-term mortality; however, when surviving the acute phase, the long-term prognosis may not differ from dogs with a similarly advanced degree of MMVD but without LAT. [ABSTRACT FROM AUTHOR]

Transient myocardial thickening (TMT) in cats is a poorly characterized clinical entity. Therefore, this study aimed to provide descriptions of additional cats diagnosed with this clinical phenomenon. For this multicenter observational retrospective study, cats diagnosed with TMT were searched in three medical databases. TMT was defined for cats with at least two echocardiograms showing an increased end-diastolic left ventricular wall thickness (LVWTd; i.e. ≥6 mm) at presentation and subsequent echocardiographic normalization (i.e. LVWTd <5.5 mm). Signalment, history, clinical, laboratory, therapeutic, and outcome data were retrieved. Twenty seven cats were included. The median age was 3 years. In 9/27 cats, an antecedent event was documented. At admission, 27/27 cats had evidence of myocardial injury (median value of cardiac troponin I 5.5 ng/mL), 25/27 cats had congestive heart failure, 13/27 cats had hypothermia, 8/27 cats had systemic hypotension, 7/27 cats had bradycardia, and 7/27 cats had electrocardiographic evidence of an arrhythmia. The median LVWTd was 6.4 mm. A potential cause of myocardial injury was identified in 14/27 cats. The median time from diagnosis to a significant reduction in LVWTd was 43 days. TMT can be diagnosed in a wide range of cats, including young subjects. An antecedent predisposing event and/or a possible causative trigger can be identified in some. The reduction in LVWTd that defines this phenomenon usually occurs over a variable time frame. This study represents the largest investigation of TMT in cats and provides additional information on this uncommon clinical entity. [ABSTRACT FROM AUTHOR]

An 11-year-old mixed breed dog was presented with exercise intolerance and syncope. At admission, transthoracic echocardiography revealed myxomatous mitral valve disease (MMVD) associated with severe left atrial (LA) enlargement and moderate anechoic pericardial effusion with a hyperechoic density suggestive of a thrombus. Rupture of the LA free wall secondary to MMVD was suspected, and medical therapy with furosemide and pimobendan was initiated. After one month, recheck echocardiography showed mild anechoic pericardial effusion and an acquired atrial septal defect with a left-to-right intracardiac shunting flow. In light of the dog's history, the latter finding was suspected to be secondary to a further rupture of the LA wall due to MMVD, this time affecting the interatrial septum. The images described here allow us to suspect that sequential LA wall ruptures developed over time in the same subject affected by MMVD, a clinical presentation not previously described in veterinary medicine. [ABSTRACT FROM AUTHOR]

The T wave is a poorly characterized electrocardiographic variable in small animals. Therefore, this study aimed to describe T wave features in a large population of healthy dogs. Medical records were reviewed to identify healthy dogs ≥one-year-olds that underwent an electrocardiogram. T wave qualitative (morphology, polarity, and concordance between R and T waves) and quantitative (duration, amplitude, mean electrical axis, ratio between T and R waves amplitudes, interval from the peak to the end of the T wave, and ratio between the duration of the latter interval and that of the QT) variables were evaluated. Continuous and categorical variables were compared between dogs of distinct sex, body weight (BW), age and somatotype using the Mann–Whitney U test and χ2 test, respectively. Spearman's correlation coefficients between quantitative variables and age and BW were calculated. Reference intervals of quantitative variables were determined in the overall population. One hundred and twenty-nine dogs were enrolled. Concerning morphology, the asymmetrical (slow/fast) pattern occurred more frequently than the symmetrical and biphasic ones. Concerning polarity, positive T waves occurred more frequently than negative and neutral ones. T and R waves were predominantly concordant. No meaningful differences were found when comparing qualitative and quantitative variables between dogs of distinct sex, BW, age and somatotype. No significant correlations were found between quantitative variables and age and BW. Reference intervals of quantitative variables are provided. Canine T wave features were addressed and statistically reliable reference intervals made available for clinical use. [ABSTRACT FROM AUTHOR]

Whether a brachymorphic conformation may lead to electrocardiographic peculiarities diverging from generic reference intervals (RIs) cited in textbooks remains to be established. Therefore, this study aimed at evaluating electrocardiographic variables in one of the most common brachymorphic breed, namely the French Bulldog (FB). Medical records were retrospectively reviewed to identify healthy FBs ≥1-year-old that underwent an electrocardiogram. The Mann–Whitney U test or the Student's t-test was used to compare continuous variables among male and female dogs, while the χ2 test was used for categorical variables. Spearman's correlation coefficients between electrocardiographic measurements and age and body weight were also calculated. Moreover, electrocardiographic RIs were determined. Eighty healthy FBs were enrolled; their electrocardiographic variables fitted with generic RIs, with the exception of the QRS-complex mean electrical axis (QRS-MEA). The median QRS-MEA value was 43.5° (from −18° to +90°). A QRS-MEA shift was found in 24/80 (30%) dogs; in all cases, it was a left shift (median 26°, from −18° to +39°). Specifically, 20 dogs showed a slight left shift (from +39° to +14°), while four dogs showed a marked one (from +9° to −18°). No meaningful differences were found when comparing electrocardiographic variables between males and females. No significant correlations between electrocardiographic variables and age or body weight were found, with the exceptions of the P-wave amplitude, PQ-interval duration and QT-interval duration. Healthy FBs can present a left shift of QRS-MEA. These data should be considered when interpreting FBs' electrocardiograms. [ABSTRACT FROM AUTHOR]

Urine chemistry has received growing attention to estimate the diuretic response in dogs with cardiac disease. The aim of the study was to evaluate the impact of time elapsed between the oral furosemide administration and sample collection on urine chemistry in dogs with myxomatous mitral valve disease (MMVD) receiving diuretic therapy in American College of Veterinary Internal Medicine (ACVIM) stage C. Seventy-three dogs with MMVD ACVIM stage C and 106 healthy dogs were prospectively included. Dogs with MMVD were divided, based on the time of sampling, in morning group (MMVD-MG) of one to 6 h and an evening group (MMVD-EG) over 6 h from oral furosemide administration. Analogously, healthy dogs sampled between 9 a.m. and 1 p.m. and between 2 and 7 p.m. were divided in a morning group (H-MG) and an evening group (H-EG), respectively. Urine chemistry, including fractional excretion of electrolytes, was evaluated and compared among groups. Higher excretion of sodium and chloride and higher urine sodium to urine potassium ratio (uNa+:uK+) were detected in MMVD-MG than MMVD-EG (P = 0.021, P = 0.038, and P = 0.016, respectively). Natriuresis, chloriuresis, and uNa+:uK+ were higher in MMVD-MG than H-MG, while no differences were found in the comparison between H-MG and H-EG and between MMVD-EG and H-EG. Urinary electrolyte excretion is significantly increased within 6 h from furosemide administration in MMVD ACVIM stage C dogs. Time of sampling from furosemide administration significantly affects urine chemistry in MMVD dogs and should be considered in clinical practice and the research field. [ABSTRACT FROM AUTHOR]

An asymptomatic nine-year-old Dobermann Pinscher underwent a screening for dilated cardiomyopathy. Echocardiography revealed left ventricular eccentric hypertrophy and systolic dysfunction; the rest of the echocardiographic parameters were within normal limits. Holter monitoring demonstrated sinus rhythm as the dominant cardiac rhythm during the first hours of the recording. Then, during a period of physiologically enhanced vagal tone (sleep), spontaneous development of atrial flutter (AFL) associated with variable ventricular response was documented. Alternation between AFL and paroxysmal atrial fibrillation was also observed. Subsequently, during a period of physiological increase of sympathetic tone (physical activity/excitement), spontaneous conversion of AFL to sinus rhythm occurred. In light of these findings, a presumptive diagnosis of vagal AFL was made. The images here described allow us to study the onset, behavior and termination of this intriguing electrocardiographic entity. [ABSTRACT FROM AUTHOR]

Although transient deep and giant negative T waves (NTWs) may develop during myocardial injury (MI) in humans, no data exist on this repolarization abnormality in canine MI. Therefore, this study aimed to describe the occurrence of transient deep/giant NTWs in dogs with MI. Medical records were retrospectively searched to identify dogs with MI and transient deep/giant NTWs. Signalment, history, and selected diagnostic test results were reviewed. Data analysis was descriptive. Six cases were diagnosed with MI associated with deep (n = 1) and giant (n = 5) transient NTWs. Myocardial injury was classified as acute in all cases and was due to snake envenomation (n = 3), sepsis (n = 2), and systemic inflammatory response syndrome (n = 1). At the time of deep/giant NTWs identification, all dogs had elevated cardiac troponin I and ≥1 echocardiographic abnormality of the left ventricular structure and/or function. Moreover, all dogs with giant NTWs had prolonged QT intervals. After the MI resolution, T-wave polarity and QT-interval duration became normalized in all dogs. Moreover, left ventricular morphological and functional parameters were completely normalized in four dogs. In contrast, ventricular echogenicity remained heterogeneous in two dogs, despite otherwise normalized ventricular parameters. Five dogs were still alive at the conclusion of the study. Transient deep/giant NTWs may develop in dogs with acute MI and T-wave polarity changes seem to occur synchronously with the evolution of myocardial damage. Moreover, transient deep/giant NTWs seem associated with a favorable prognosis in canine MI. [ABSTRACT FROM AUTHOR]

A 4-year-old Dachshund was referred for management of a mandibular fracture. The dog underwent cardiopulmonary arrest after sedation for skull radiography. Cardiopulmonary resuscitation was started immediately, and return of spontaneous circulation was rapidly obtained. However, after resuscitation, the dog was hemodynamically unstable. Additionally, global left ventricular systolic dysfunction and a focal hyperechoic myocardial lesion were found echocardiographically, and serum cardiac troponin I was severely elevated (82.80 ng/mL, upper hospital limit <0.7 ng/mL). The dog remained hospitalized in the intensive care unit and received supportive medical therapies, including intravenous inotropes (pimobendan, dobutamine). Over the following days, progressive hemodynamic and echocardiographic improvement was achieved in response to treatment. Moreover, after 72 h, a significant reduction of serum cardiac troponin I (9.80 ng/mL) was documented. On recheck, 3 weeks after discharge, the dog was clinically stable, and both left ventricular systolic function and serum cardiac troponin I (0.10 ng/mL) were normal. Based on clinical and instrumental findings after cardiopulmonary resuscitation, a probable diagnosis of reversible postresuscitation myocardial dysfunction associated with transient myocardial injury was made. [ABSTRACT FROM AUTHOR]

This report describes the transthoracic and transesophageal echocardiographic features of cor triatriatum sinister in an asymptomatic 6-year-old male French bulldog. Although cor triatriatum sinister represents a well-known and widely described cardiac malformation in humans, its description in the canine population is rare. In this clinical case, non-invasive echocardiographic techniques were helpful in visualizing and characterizing the lesion, allowing a valuable assessment of the malformation, and its hemodynamic consequences. [ABSTRACT FROM AUTHOR]

Preexcitation alternans and orthodromic atrioventricular reciprocating tachycardia were diagnosed in a 3-month-old Boxer. The images described here show how conventional electrocardiographic techniques (12-lead surface electrocardiography, 24-hour Holter monitoring, and ladder diagram) can be interpreted to gain detailed information on presence of canine atrioventricular accessory pathways and their conduction properties. [ABSTRACT FROM AUTHOR]

Abstract Objectives To assess the ability of electrocardiography (ECG) to predict left ventricular hypertrophy (LVH) in the cat and to investigate the prognostic value of selected ECG variables in cats with LVH. Animals Fifty-seven privately owned cats: 22 clinically healthy cats and 35 cats with LVH. Material and methods This is a clinical cohort study. Echocardiographic diagnosis and surface ECG were available. Electrocardiography analysis included rhythm diagnosis and specific electrocardiographic measurements. In cats with LVH, cause of death and outcome data were recorded and analyzed using Kaplan–Meier curves. Results The presence of arrhythmia had sensitivity and specificity of 31% and 100%, respectively, for identifying LVH. Among ECG measurements, duration of QT interval (QT) and QT interval corrected for heart rate (QTc) was statistically different between healthy cats and cats with LVH (p = 0.007). Overall, the most accurate cutoffs to identify LVH were QT > 170 ms (sensitivity and specificity 48.3% and 91%, respectively) and QTc > 188 ms (sensitivity and specificity 62% and 77%, respectively). In healthy cats, the highest QT and QTc values were 180 ms and 200 ms, respectively. Mean survival time was 58 days and indeterminable for cats with QT > 180 ms and QT ≤ 180 ms, respectively (p = 0.042) and 125 days and indeterminable for cats with QTc > 200 ms and QTc ≤ 200 ms, respectively (p = 0.017). Conclusions Arrhythmias as well as prolonged QT and QTc are useful ECG parameters in identifying LVH and predicting survival in affected cats. [ABSTRACT FROM AUTHOR]

A 14-year-old American Staffordshire terrier was presented for episodes of exercise-induced syncope. At admission, atrial flutter coupled to third-degree atrioventricular block was diagnosed electrocardiographically. On the second day of hospitalization, surface electrocardiogram revealed spontaneous conversion to sinus rhythm with persistence of atrioventricular block. Complete transthoracic echocardiograms were performed after each electrocardiographic examination. The combined use of conventional echocardiography with tissue Doppler imaging-based modalities allowed to investigate the atrial electromechanical correlation and function during typical atrial flutter and after its resolution. [ABSTRACT FROM AUTHOR]