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Arrhythmogenic right ventricular cardiomyopathy (ARVC) is an inherited myocardial disease seen in dogs, cats, and humans. A common entity in Boxers and the related English bulldog, the disease is characterized by fatty or fibrofatty replacement of the myocardium, ventricular arrhythmias, and the potential for syncope or sudden death. In some individuals, concomitant left ventricular involvement results in systolic dysfunction and a progression to congestive heart failure. The clinical and pathological characteristics of ARVC share many similarities in dogs and humans, and Boxers serve as an important spontaneous model of the disease. Although multiple mechanisms have been implicated in the pathogenesis of ARVC, the disease is ultimately considered to be a disorder of the desmosome. Multiple causal genetic mutations have been identified in people, and over 50% of affected humans have an identifiable mutation in desmosomal proteins. To date, only a single genetic mutation has been associated with ARVC in Boxer dogs. Other as-yet-undiscovered genetic mutations and epigenetic modifiers of the disease are likely. Treatment of ARVC in dogs is focused on controlling ventricular arrhythmias and associated clinical signs. This article will review the pathophysiology, clinical diagnosis, treatment, and prognosis of ARVC in the dog., Competing Interests: Conflict of Interest Statement The authors declare no conflicts of interest., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Introduction/objectives: The objectives were to conduct a survey of cardiologists on their recent experiences with cats that have dilated cardiomyopathy (DCM) and to retrospectively review individual cases of feline DCM., Animals, Materials and Methods: Part one: A survey was distributed to cardiologists with questions regarding caseload and clinical management of cats with DCM diagnosed over the past two years. Part two: Cardiologists completing the survey were invited to submit data from cats recently diagnosed with DCM. Data on signalment, clinical signs, diet, echocardiographic measurements and outcome were recorded., Results: Part one: From 52 completed surveys, many cardiologists responded that measuring and supplementing taurine and recommending a diet change in cats with DCM are common practices. Few (15%) cardiologists reported an increase in the number of feline DCM cases over the past two years, although some had cases that improved even if taurine deficiency was not present. Part two: Twenty of 37 (54%) cats ate low pea/lentil (low PL) diets, and 14/37 (38%) ate high PL diets at the time of diagnosis; three had incomplete diet information. Two of 13 cats (15%) in which taurine was measured had levels below the reference range. After adjusting for other variables, cats eating high PL diets that changed diets after diagnosis had a significantly longer survival time than that of cats eating high PL diets that did not change diets after diagnosis (P = 0.025)., Conclusions: Additional research is warranted to determine whether there could be a possible association between diet and DCM in cats., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objectives: To determine whether there are differences in measures of longitudinal right ventricular (RV) systolic function among Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC) compared with healthy control Boxer dogs. To explore relationships between markers of RV systolic function and age, body weight, gender, arrhythmia frequency, and markers of left ventricular (LV) systolic function in Boxer dogs., Animals: The study included 50 client-owned Boxer dogs., Methods: This is a retrospective echocardiographic study. Tricuspid annular plane systolic excursion (TAPSE) and pulsed wave tissue Doppler imaging-derived systolic myocardial velocity of the lateral tricuspid annulus (S') were measured in healthy control Boxers (n = 18), Boxers with ARVC and normal LV systolic function (n = 19), and Boxers with ARVC and reduced LV systolic function (n = 13)., Results: Tricuspid annular plane systolic excursion (p=0.002) and S' (p=0.001) were significantly different between affected and control groups. Significant correlations were found between measures of left heart size and function and both TAPSE and S'. No correlations were found between RV function parameters and age, gender, or body weight in this fairly homogeneous, single-breed population. Receiver operating characteristic curve analysis revealed that both TAPSE and S' had an area under the curve of 0.77 in distinguishing healthy Boxers from those with ARVC., Conclusions: Tricuspid annular plane systolic excursion and S' are reduced in Boxers with ARVC. In contrast to prior studies evaluating these parameters in dogs of different breeds and body types, no correlation was found between markers of RV function and body weight in this population of Boxer dogs., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objectives: To evaluate the responsiveness and optimal timing of a validated health-related quality of life questionnaire, and to assess the relationship between quality of life, severity of disease, and N-terminal pro B-type natriuretic peptide (NT-proBNP) in cats with acute congestive heart failure (CHF)., Animals: Thirty client-owned cats with acute CHF., Methods: Echocardiography, International Small Animal Cardiac Health Council (ISACHC) stage, and NT-proBNP were assessed in cats within 36 h of admission. The Cats' Assessment Tool for Cardiac Health (CATCH) Questionnaire (range of 0-80, with 80 being the worst possible score) was completed by cat owners and ISACHC stage was assessed at the time of hospital discharge, 3 days after discharge, and 7-14 days after discharge. NT-proBNP concentration was reassessed 7-14 days after discharge., Results: The ISACHC stage at time of admission improved significantly by reevaluation 7-14 days after discharge (P < 0.001). The decrease in median NT-proBNP concentration from time of admission (655 pmol/L; range, 188 to >1500 pmol/L) to reevaluation (583 pmol/L; range, 41 to >1500 pmol/L) was not significant (P = 0.59). Median CATCH score was 26 (range, 0-70) at baseline, 19 (range, 0 to 61) at discharge, and 19 (range, 2-49) 7-14 days after discharge (P = 0.89). CATCH scores did not correlate with NT-proBNP concentrations or ISACHC stage., Conclusions: These results suggest that the CATCH questionnaire requires further refinement for uses requiring a responsive instrument in cats with acute CHF., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objectives: Cardiac cachexia, a loss of lean body mass caused by heart disease, often accompanies congestive heart failure (CHF). Blocking myostatin, which is a protein that inhibits muscle growth, appears to greatly enhance muscle size and strength in rodent models and human clinical trials. The objective of this study was to evaluate a dog-specific myostatin antagonist (CAP-031) in a pilot study to test its safety and efficacy in dogs with CHF and cardiac cachexia., Animals: Dogs with CHF and cardiac cachexia., Methods: Eligible dogs received four weekly subcutaneous injections of CAP-031. Endpoints were body weight, body condition score (BCS, on a 1-9 scale), muscle condition score (MCS, on a five-point scale, where 0 = no muscle loss and 4 = severe muscle loss), appetite, and a quality of life (QOL) score., Results: Seven dogs with CHF and moderate-to-severe cachexia were enrolled in the study. For the six dogs that completed the study, the median age was 8.8 years (range 6.4-10.6). At baseline, the median body weight was 27.0 kg (range 17.3-62.0), the median BCS was 4 (2-5), and median MCS was 3 (3-4). There were no significant changes in body weight, BCS, appetite, or QOL score. The change in MCS (from a median of 3 at baseline to a median of 2.5 at week 4) was not statistically significant (p = 0.06)., Conclusions: The myostatin antagonist appeared to be well tolerated in most dogs. Earlier identification of cachexia is important, and randomized, controlled trials of myostatin antagonists or other drugs to treat cardiac cachexia are needed., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objectives: To describe a series of dogs with pulmonary artery dissection and patent ductus arteriosus (PDA)., Animals: Eight dogs., Methods: Retrospective case series., Results: Pulmonary artery dissection was diagnosed in 8 dogs, 3 were Weimaraners. Four dogs presented in left-sided congestive heart failure, 4 presented for murmur evaluation and without clinical signs, and 1 presented in right-sided congestive heart failure. In 7 dogs the dissection was first documented concurrent with a diagnosis of uncorrected PDA. In the other dog, with pulmonary valve stenosis and PDA, the dissection was observed on autopsy examination 17 months after balloon pulmonary valvuloplasty and ductal closure. Median age at presentation for the 7 dogs with antemortem diagnosis of pulmonary artery dissection was 3.5 years (range, 1.5-4 years). Three dogs had the PDA surgically ligated, 2 dogs did not undergo PDA closure, 1 dog failed transcatheter occlusion of the PDA with subsequent surgical ligation, 1 dog underwent successful transcatheter device occlusion of the PDA, and 1 dog had the PDA closed by transcatheter coil delivery 17 months prior to the diagnosis of pulmonary artery dissection. The 2 dogs that did not have the PDA closed died 1 and 3 years after diagnosis due to heart failure., Conclusions: Pulmonary artery dissection is a potential complication of PDA in dogs, the Weimaraner breed may be at increased risk, presentation is often in mature dogs, and closure of the PDA can be performed and appears to improve outcome., (Copyright © 2014 Elsevier B.V. All rights reserved.)

This report describes an unusual congenital abnormality in a dog in which multiple distinct membranes were observed within the right atrium, creating obstruction to venous return from both the cranial vena cava and the caudal vena cava. A persistent left cranial vena cava was also identified. In addition to a membrane in the typical location for cor triatriatum dexter, the dog also had a perforated membrane separating the main right atrial body and tricuspid valve from a more cranial right atrial chamber and the right cranial vena cava. Balloon dilation was performed successfully to alleviate the obstruction to systemic venous return created by the two membranes. Due to the unusual anatomic features, angiography plus echocardiography was useful to completely characterize the congenital abnormality prior to intervention., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Objective: To prospectively evaluate the diagnostic accuracy of a point-of-care (POC) N-terminal pro-B-type natriuretic peptide (NT-proBNP) ELISA to assess the likelihood of moderate to severe occult heart disease (OcHD) in a clinical population of cats suspected to have heart disease., Animals: One hundred and forty-six asymptomatic client-owned cats with a heart murmur, gallop rhythm, arrhythmia, or cardiomegaly., Methods: Physical examination, blood pressure measurement and echocardiography were performed prospectively. Point-of-care ELISA was visually assessed as either positive or negative by a reader blinded to the echocardiographic results., Results: Forty-three healthy cats, 50 mild OcHD, 31 moderate OcHD, 6 severe OcHD, and 16 cats equivocal for OcHD were examined. Cats with OcHD included 65 with hypertrophic cardiomyopathy, 6 with restrictive or unclassified cardiomyopathy, 1 with arrhythmogenic right ventricular cardiomyopathy, and 15 with non-cardiomyopathic forms of heart disease. Point-of-care ELISA differentiated cats with moderate or severe OcHD with sensitivity/specificity of 83.8%/82.6% and overall accuracy of 82.9%. Positive POC ELISA increased likelihood of moderate or severe OcHD by a factor of 4.8 vs. those that tested negative. Point-of-care ELISA differentiated cats with moderate or severe cardiomyopathic OcHD with sensitivity/specificity of 88.6%/81.3% and overall accuracy of 83.2%., Conclusion: In a select sample of cats referred for cardiac evaluation, positive POC NT-proBNP ELISA increases likelihood of moderate to severe OcHD while negative POC NT-proBNP ELISA result excludes moderate to severe OcHD., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Hypothesis/objectives: To describe the therapeutic use of pimobendan in cats, describe the patient population to which it was administered, document potential side effects and report the clinical course following administration of pimobendan in conjunction with standard heart failure therapy. It is hypothesized that cats with advanced heart disease including congestive heart failure from a variety of causes will tolerate pimobendan with a minimum of side effects when used in treatment in conjunction with a variety of other medications., Animals, Materials and Methods: One hundred and seventy client owned cats with naturally occurring heart disease, one hundred and sixty four of which had congestive heart failure. Medical records were reviewed and owners and referring veterinarians were contacted for follow-up data. Data collected included pimobendan dose, other medications administered concurrently, data collected at physical examination, presence or absence of heart failure, adverse effects, classification of heart disease, echocardiographic data and survival time. The data were analyzed for significance between the initial visit and any follow-up visits., Results: All cats were treated with pimobendan. The median pimobendan dose was 0.24 mg/kg q 12 h. Pimobendan was used in combination with multiple concurrent medications including angiotensin converting enzyme inhibitors, diuretics and anti-thrombotics. Five cats (3.0%) had potential side effects associated with pimobendan. One cat (0.6%) had presumed side effects severe enough to discontinue pimobendan use. Median survival time for 164 cats with congestive heart failure after initiation of pimobendan was 151 days (range 1-870)., Conclusion: Pimobendan appears to be well tolerated in cats with advanced heart disease when used with a variety of concurrent medications. Randomized controlled studies need to be performed to accurately assess whether it is efficacious for treatment of congestive heart failure in cats., (Copyright © 2011 Elsevier B.V. All rights reserved.)

The case reported herein describes the placement of a permanent transvenous pacemaker in an older dog with a previously undiagnosed persistent left cranial vena cava (PLCVC) and recent onset symptomatic third-degree atrioventricular (AV) block. On presentation the dog was found to have atrial flutter and third-degree AV block and echocardiography demonstrated evidence of chronic valvular disease and pulmonary arterial hypertension. The persistent left cranial vena cava was discovered via angiography when difficulties were encountered with pacemaker placement. Successful right ventricular pacing necessitated passage of the lead through the coronary sinus. The attendant complications in pacemaker placement in the presence of a PLCVC are well-described in man but, to the authors' knowledge, have not been described in companion animals.