BackgroundMyocarditis is a disease caused by numerous etiological factors and characterized by a non-specific course. The only method allowing for precise characterization of inflammatory changes is the histopathological examination of heart muscle specimens. The study was conducted on heart muscle preparations from 11 dogs with ante-mortem diagnosis of cardiac disease. Animals presented with a poor response to an applied treatment or had suspected sudden cardiac death. The heart specimens were taken post-mortem, preserved and stained with haematoxylin and eosin. Subsequently, the presence and intensity of changes, i.e. inflammatory infiltration, the amount of connective tissue and features of cardiomyocyte degeneration were estimated. The specimens from dogs suspected of having a myocarditis of bacteriological etiology underwent additional bacteriological and immunohistochemical examination.ResultsThe examination revealed an inflammatory infiltration of variable intensity combined with the degenerative changes in all dogs. There were vegetative and abnormal cystic forms of Borrelia burgdorferi sensu lato in 6 dogs. A Staphylococcus aureus infection was confirmed in one dog and an acute coronary syndrome with neutrophil infiltration was revealed in another one.ConclusionsAlthough the clinical pattern in patients with myocarditis is diverse, the definitive morphological diagnosis is made based on the histopathological examination. This examination can lead to a better understanding of the pathogenesis of the disease. To the best of our knowledge, this is the first description of myocarditis combined with the presence of spore forms of Borrelia burgdorferi sensu lato in the heart specimens of dogs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13620-014-0028-8) contains supplementary material, which is available to authorized users.

IntroductionThe prevalence of arrhythmias in dogs and the influence of sex, breed, age, and body weight were analysed over a seven-year span.Material and MethodsIn total, 1189 referrals for cardiological examination by electrocardiography were received at one academic centre in Poland between 2008 and 2014. The largest proportion of the examined dogs were cross-breeds with body weight below 25 kg (n = 153, 12.87%), followed by German Shepherds (n = 122, 10.26%), Labrador Retrievers (n = 68, 5.72%), Yorkshire Terriers (n = 63, 5.3%), and Boxers (n = 60, 5.05%). Retrospective analysis was made of 1201 standing or right recumbent electrocardiograms without pharmacological sedation. The prevalence of arrhythmias was examined in terms of sex, age, body weight, and breed of the dogs.ResultsA total of 630 (52.46%) electrocardiograms showed no signs of arrhythmia, but 96 (7.99%) and 475 (39.55%) pointed to physiological and pathological arrhythmias respectively. The most commonly diagnosed type was atrial fibrillation with 33.68% incidence, followed by ventricular arrhythmias (28%), sinus pauses (27.58%), supraventricular arrhythmias (24%), and atrioventricular blocks (22.95%). Pathological arrhythmias were most commonly found in male dogs and in German Shepherds.ConclusionsAtrial fibrillation predominated, followed by premature ventricular complexes. Male dogs were generally more prone to heart rhythm disturbances.

Introduction: Pacemaker implantation is the only effective symptomatic treatment for life-threatening bradyarrhythmias. Major complications observed after implantation of cardiac pacemakers include lead dislocation, loss of pulse generator function, and inadequate stimulation. The aim of this retrospective single-centre study was to analyse the indications for pacemaker implantation and the incidence and types of complications associated with this procedure in dogs treated for symptomatic bradyarrhythmia. Material and Methods: The retrospective analysis included 31 dogs with symptomatic bradyarrhythmia, implanted with permanent cardiac pacemakers in 1992–2017. The list of analysed variables included patient age, breed, sex, indication for pacemaker implantation, comorbidities, and the incidence of procedure-related complications along with the type thereof. Results: The most common indication for pacemaker implantation was 3rd degree AVB, followed by SSS, advanced 2nd degree AVB, and PAS. Pacemaker implantation was associated with a 35% overall complication rate and 6.45% periprocedural mortality. There were no significant differences in terms of procedure-related complications with regard to age, sex, breed, indications for pacemaker implantation, or comorbidities. Conclusions: Cardiac pacing is the only effective treatment of symptomatic bradycardia, but as an invasive procedure, may pose a risk of various complications, including death.

The study has focused on the retrospective analysis of cases of coexisting congenital aortic stenosis (AS) and pulmonary artery stenosis (PS) in dogs.The research included 5463 dogs which were referred for cardiological examination (including clinical examination, ECG and echocardiography) between 2004 and 2014. Aortic stenosis and PS stenosis were detected in 31 dogs. This complex defect was the most commonly diagnosed in Boxers -7 dogs, other breeds were represented by: 4 cross-breed dogs, 2 Bichon Maltais, 3 Miniature Pinschers, 2 Bernese Mountain Dogs, 2 French Bulldogs, and individuals of following breeds: Bichon Frise, Bull Terrier, Czech Wolfdog, German Shepherd, Hairless Chinese Crested Dog, Miniature Schnauzer, Pug, Rottweiler, Samoyed, West Highland White Terrier and Yorkshire Terrier. In all the dogs, the murmurs could be heard, graded from 2 to 5 (on a scale of 1-6). Besides, in 9 cases other congenital defects were diagnosed: patent ductus arteriosus, mitral valve dysplasia, pulmonary or aortic valve regurgitation, tricuspid valve dysplasia, ventricular or atrial septal defect. The majority of the dogs suffered from pulmonary valvular stenosis (1 dog had supravalvular pulmonary artery stenosis) and subvalvular aortic stenosis (2 dogs had valvular aortic stenosis).Conclusions and clinical relevance -co-occurrence of AS and PS is the most common complex congenital heart defect. Boxer breed was predisposed to this complex defect. It was found that coexisting AS and PS is more common in male dogs and the degree of PS and AS was mostly similar.

size, diameters of coronary arteries, susceptibility to coronary atherosclerosis, coronary stent-related restenosis, infarct development and post-infarction remodeling in these two species, and owing Swine are a well-recognized animal model for human cardiovascular diseases [1][2][3][4]. Porcine models have been increasingly used in human cardiovascular research due to similarities in the heart Agnieszka Noszczyk-Nowak 1, A-D, F , Alicja Cepiel 1, B, C, F , Adrian Janiszewski 2, B, E, F , Robert Pasławski 3, B, F , Jacek Gajek 4, A, E, F , Urszula Pasławska 1 A -research concept and design; B -collection and/or assembly of data; C -data analysis and interpretation; D -writing the article; E -critical revision of the article; F -final approval of article AbstractBackground. Swine are a well-recognized animal model for human cardiovascular diseases. Despite the widespread use of porcine model in experimental electrophysiology, still no reference values for intracardiac electrical activity and conduction parameters determined during an invasive electrophysiology study (EPS) have been developed in this species thus far. Objectives. The aim of the study was to develop a set of normal values for intracardiac electrical activity and conduction parameters determined during an invasive EPS of swine. Material and Methods. The study included 36 healthy domestic swine (24-40 kg body weight). EPS was performed under a general anesthesia with midazolam, propofol and isoflurane. The reference values for intracardiac electrical activity and conduction parameters were calculated as arithmetic means ± 2 standard deviations. Results. The reference values were determined for AH, HV and PA intervals, interatrial conduction time at its own and imposed rhythm, sinus node recovery time (SNRT), corrected sinus node recovery time (CSNRT), anterograde and retrograde Wenckebach points, atrial, atrioventricular node and ventricular refractory periods. No significant correlations were found between body weight and heart rate of the examined pigs and their electrophysiological parameters. Conclusions. The hereby presented reference values can be helpful in comparing the results of various studies, as well as in more accurately estimating the values of electrophysiological parameters that can be expected in a given experiment (Adv Clin Exp Med 2016, 25, 6, 1249-1254).

The presence of an accessory atrioventricular conduction pathway may provide the anatomical basis for some tachyarrhythmias. Persistent tachyarrythmias may result in the development of systolic dysfunction or tachycardiomyopathy and eventual progression to heart failure. In this paper we report the successful ablation of an accessory pathway involved in the pathogenesis of persistent orthodromic atrioventricular reciprocating tachycardia (AVRT) and heart failure in a 3-year-old male Labrador retriever. Electrophysiological study and radiofrequency (RF) catheter ablation were performed under general anesthesia. Electrophysiological study revealed AVRT resulting from a retrograde conduction via a right posteroseptal accessory pathway. The successful RF ablation of the accessory pathway resulted in the resolution of the tachycardia and return of normal sinus rhythm. Medical management of heart failure was withdrawn and no episodes of recurrent tachyarrhythmia were documented during a 3-month follow-up.

A 6-month-old, 17 kg, male Labrador Retriever was presented for an evaluation of a suspected patent ductus arteriosus (PDA). Transthoracic echocardiography confirmed a left-to-right shunting PDA with a minimal ductal diameter of 3.5 mm. A transcatheter PDA occlusion was performed, and a 16 mm Amplatzer Vascular Plug II was selected for the procedure. Within 13 days of discharge, the dog developed sudden lethargy, tachypnea, and coughing after physical activity. Thoracic radiographs showed the Amplatzer device to be abnormally positioned in the lumen of the pulmonary artery with a distinct alveolar pattern. Given the progressive cardiopulmonary distress of the dog, the owners opted for euthanasia. In the present case study, the authors have not been able to satisfactorily explain why the device migrated several days after the procedure. In order to avoid device migration, greater emphasis should be placed on strict activity restriction in dogs after percutaneous PDA occlusion.

SummaryThe majority of anaesthetics used in studies regarding heart arrhythmias may affect the cardiac conduction system, thus influencing the results. In veterinary medicine, xylazine, medetomidine and dexmedetomidine are commonly used for premedication in laboratory and companion animals. To date, there have been no studies assessing the effect of these substances on the cardiac conduction system. The aim of this study was to assess the effect of xylazine, medetomidine and dexmedetomidine on the parameters of the cardiac conduction system in pigs. The study was carried out on 18 Great White Polish male pigs weighing from 21 to 40 kg. The animals were divided into three equal groups. The animals from the first group received xylazine at a dose of 2 mg/ kg i.v.; those from the second group received medetomidine at 40 mcg/kg i.v.; and those from the third group received dexmedetomidine at 10 mcg/kg i.v. The electrophysiological activity of the heart was analysed using an invasive electrophysiological study (EPS). During the EPS, a decrease in the heart rate after substance administration was observed in all animals, but there were no statistically significant differences in the cardiac conduction parameters. A pro-arrhythmic effect of xylazine was observed, but no statistically significant changes in the EPS parameters were noted. Our results indicate that medetomidine and dexmedetomidine may be used as standard premedication drugs in electrophysiological studies in pigs. Their use may facilitate animal preparation procedures without affecting study results.