Cardiovascular indicators and mitral valve disease in dogs with spontaneous hypercortisolism - prospective evaluation

Background: Canine hypercortisolism (HC) is the most prevalent endocrinopathy in dogs in southern Brazil. The prognosis depends on several factors including the general health status, owners´ commitment, and the development of disease complications and comorbidities occurrence, such as cardiovascular complications including mitral valve disease (MVD), systemic arterial hypertension, and left ventricular hypertrophy. The main objective of the present study was to assess cardiovascular parameters in canine HC, based on investigating survival-related variables. The study also aimed to evaluate the influence of concurrent preclinical (MVD) on dogs` survival and the impact of HC on MVD progression. Materials, Methods & Results: A total of 25 dogs with spontaneous HC were enrolled and divided into 2 subgroups accordingly to their echocardiographic findings: group HC (normal echocardiography at first evaluation, n = 16); and group HC + MVD (concurrent presence of stages B1 and B2 MVD diagnosed at the first evaluation, n = 9). The patients were evaluated at diagnosis (T0); 6 months after treatment begging (T1); and after 12 months of treatment (T2). The owners were further contacted by phone or e-mail for 1 more year after T2 regarding survival information. A control group (CG, n = 20) was also evaluated at T0 and T1. At each evaluation, dogs were submitted to a complete clinical evaluation and physical exam, associated with a minimum database (CBC, serum biochemistry, and urine analysis) and cardiovascular evaluation composed of systolic blood pressure determination, electrocardiogram (ECG), and echodopplercardiography. In the HC group, 11/16 dogs underwent the evaluation at T2, while 4/9 dogs from the HC + MVD group and 17/20 dogs from the CG underwent the evaluation at T2. Five dogs (31.25%) from the HC group and 4 dogs (44.44%) from the HC + MVD group died before the end of the follow-up period. In the control group, only 1 dog (5.26%) died before the end of the study. Despite the higher mortality in the HC + MVD group during the follow-up period, there was no significant difference (P = 0.632) in survival when compared with the HC group. The MVD of 4 dogs included in the HC + MVD group was classified as stage B1, while the other 5 dogs were classified as stage B2. Only 1 dog from the CG developed stage B1 MVD in the period studied; however, progression of the MVD stage was documented in 1/4 of dogs in the HC + MVD group and MVD development was documented in 3/11 of dogs from the HC group from T0 to T2. The odds ratio (OR) and respective 95% confidence interval (95%CI) for HC as a risk factor for MVD progression were 4.267 (0.4268 - 42.65; P = 0.342). Exercise intolerance (12/16 dogs) and dyspnea (6/16 dogs) were the cardiorespiratory clinical signs with the highest incidence in the HC group at T0. When compared to the control group, both exercise intolerance (P < 0.001) and dyspnea (P = 0.03) occurrence were significantly higher in the HC group. The age (P = 0.001) and the occurrence of dyspnea (P = 0.036) at diagnosis were significantly higher in dogs with HC that died during the follow-up than those that remained alive. Regarding the occurrence of cardiac arrhythmias verified by ECG, no statistically significant differences were observed among groups. Discussion: The study suggests that systemic hypertension and altered echocardiographic measurements did not interfere with dogs' survival; however, dyspnea was associated with a worse prognosis. Finally, it is possible to conclude that mitral valve degeneration is a common comorbidity in dogs with HC, however, it was not evidenced their interference in the survival of dogs with this endocrine disease or even a role of the HC in the progression of the MVD.

Risk of arrhythmias in dogs with structural heart disease / Potencial arrítmico de cardiopatias em cães

Presently, pet life expectancy is becoming longer and several diseases inherent to age have been diagnosed, with heart disease being a frequent finding. Although various heart diseases have different pathophysiologies, many morphological and hemodynamic changes can predispose patients to arrhythmias. The presence of arrhythmias can worsen the underlying heart disease and predispose patients to develop new alterations, making arrhythmia detection important for establishing adequate therapeutic protocols and a better prognosis. The present study aimed to determine the arrhythmias most frequently found in dogs treated at the Cardiology and Respiratory Diseases Service (SCDR) of the Small Animals Sector of the Veterinary Hospital of the Federal Rural University of Rio de Janeiro (UFRRJ), during the period from January to 2014 to December 2017, relating them to sex, age group, size, and the presence or absence of heart disease. A total of 586 medical records of dogs treated with SCDR-UFRRJ were retrospectively evaluated. Of these, 15.4% had arrhythmias, 95.6% had diagnoses of heart disease, 61.1% (55/90) were diagnosed with mitral valve disease, and 27.8% (25/90) had dilated cardiomyopathies. The most frequent rhythm disturbances were premature ventricular complexes associated with chronic degenerative mitral valve disease or dilated cardiomyopathy. Statistical analysis confirmed the risk of a cardiac patient developing rhythm or conduction alterations (OR, 4.46; p = 0.0003). In conclusion, the pathophysiology of heart failure can lead to the development of rhythm and conduction disorders.

Com a maior expectativa de vida dos animais de estimação, diversas enfermidades inerentes a idade têm sido diagnosticadas, sendo as cardiopatias um achado frequente. Apesar das diferentes cardiopatias terem fisiopatologias distintas, diversas alterações morfológicas e hemodinâmicas podem ocorrer predispondo ao aparecimento de arritmias. A presença de arritmias pode agravar a doença cardíaca de base e predispor ao desenvolvimento de novas alterações, tornando-se importante a sua detecção para instituição de protocolos terapêuticos adequados e melhor prognóstico da doença. O presente estudo teve como objetivo determinar as arritmias mais frequentemente encontradas em cães atendidos no Serviço de Cardiologia e Doenças Respiratórias (SCDR) do Setor de Pequenos Animais do Hospital Veterinário da Universidade Federal Rural do Rio de Janeiro (UFRRJ), no período de janeiro de 2014 a dezembro de 2017, relacionando-as com sexo, faixa etária, porte e presença ou não de cardiopatias. De maneira retrospectiva, foram avaliados 586 prontuários de cães atendidos no SCDR-UFRRJ. Destes, 15.4% apresentavam alguma arritmia e 95,6% apresentavam diagnostico de alguma cardiopatia, sendo 61.1% (55/90) diagnosticados com endocardiose de mitral e 27.8% (25/90) com cardiomiopatia dilatada. O distúrbio de ritmo mais frequente foram os complexos ventriculares prematuros associados a doença valvar degenerativa crônica de mitral ou a cardiomiopatia dilatada. Na análise estatística, o risco de um paciente cardiopata desenvolver alterações de ritmo ou de condução foi confirmado (OR: 4,46; p=0,0003). Conclui-se que a fisiopatologia da insuficiência cardíaca pode levar ao desenvolvimento de distúrbios de ritmo e também distúrbios de condução.

Electrocardiographic, echocardiographic and heart biomarker parameters in sheep experimentally poisoned by Palicourea marcgravii (Rubiaceae) / Parâmetros eletrocardiográficos, ecocardiográficos e de biomarcadores cardíacos em ovinos intoxicados experimentalmente por Palicourea marcgravii (Rubiaceae)

The present study aimed to identify and describe cardiac alterations in sheep experimentally poisoned with Palicourea marcgravii through analysis of serum cardiac biomarkers (serum troponin I and creatine kinase - CK-MB) and electro and echocardiographic assessments to contribute to a better understanding of the poisoning pathophysiology. P. marcgravii is the main plant within a group of 22 species that cause sudden death in Brazil; its toxic principle is sodium monofluoroacetate. Eight healthy crossbreed male sheep, aged between five and twelve months, weighing 14 to 27kg, were evaluated. The animals received 1g kg-1 of P. marcgravii plants orally. The sheep were evaluated before administering the plant (T0) through electro and echocardiography and blood collection to assess cardiac biomarkers (CK-MB and cTnI). Collections and analyses were repeated every four hours until the animal's death. During the study, there was the presence of extravasation of serum troponin I carried out in a qualitative test, with positive values at time T4, and the serum CK-MB biomarker had a peak at T4 and slightly decreased at T8. The electro and echocardiographic examinations showed that the cause of death in these animals was due to acute heart failure characterized by arrhythmias, tachycardia/ventricular fibrillation, drop in cardiac output, left ventricular (LV) systolic dysfunction by the progressive decrease in the LV ejection fraction (EF), decrease in LV fractional shortening (FS), and decrease in aortic flow velocity and aortic flow gradient. This study seems to be the first to evaluate cardiac alterations in sheep poisoned by P. marcgravii through cardiac biomarkers and electro and echocardiographic exams.

O presente estudo objetivou identificar e descrever as alterações cardíacas de ovinos intoxicados experimentalmente por Palicourea marcgravii através das análises de biomarcadores cardíacos séricos (troponina I sérica e a creatinoquinase - MB) e das avaliações eletro e ecocardiográficas contribuindo para o melhor entendimento da fisiopatologia da intoxicação. Palicourea marcgravii é a principal planta dentro de um grupo de 22 espécies que causam "morte súbita" no Brasil e seu princípio tóxico é o monofluoracetato de sódio. Foram utilizados oito ovinos saudáveis machos, sem raça definida, com idades entre cinco e doze meses e peso de 14 a 27kg. Os animais receberam 1g/kg de Palicourea marcgravii por via oral. Os ovinos foram avaliados momentos antes da administração da planta (T0) através de eletro e ecocardiograma e coleta de sangue para avaliação dos biomarcadores cardíacos (CK-MB e cTnI). As análises e coletas foram repetidas a cada quatro horas até o óbito do animal. Durante o estudo observou-se extravasamento de troponina I sérica realizada em teste qualitativo, com valores positivos já em T4, assim como o biomarcador CK-MB sérico teve seu pico de aumento em T4 e em T8 houve uma leve redução. Aos exames eletro e ecocardiográfico foi possível determinar que a causa do óbito nestes animais ocorreu devido à insuficiência cardíaca aguda caracterizada por arritmias, taquicardia/fibrilação ventricular, queda no débito cardíaco, disfunção sistólica do ventrículo esquerdo (VE) pela diminuição progressiva da fração de ejeção (EF) do VE, diminuição na fração de encurtamento (FS) do VE, diminuição da velocidade do fluxo aórtico e do gradiente do fluxo aórtico. Este é o primeiro estudo que avalia as alterações cardiológicas de ovinos intoxicados por P. marcgravii através de biomarcadores cardíacos e exames eletro e ecocardiográficos.

Diagnostic accuracy of the electrocardiogram for detection of atrial and ventricular overloads in dogs

Background: Analysis of the electrocardiogram may suggest atrial and ventricular overloads. However, it has a lowsensitivity and specificity for diagnosis of cardiac chamber overload. The accuracy of electrocardiographic interpretation can be improve using new cut-offs for the duration and amplitude of the electrocardiographic waves. Ourobjective was to evaluate the use of the electrocardiogram in the diagnosis of atrial and ventricular overload, usingechocardiography as the gold standard test for the diagnosis of atrioventricular overload. We aimed to define newcut-off values that would increase the sensitivity and specificity of the electrocardiogram for diagnosis of chamberoverload in dogs.Materials, Methods & Results: Eletrocardiogram records were obtained in 81 dogs divided into 3 groups: Group1A (healthy dogs ≤ 10 kg); Group 1B (dogs ≤ 10 kg with mitral or tricuspid valve disease); Group 2 (dogs weighingbetween 10.1 and 20 kg) and Group 3 (dogs > 20.1 kg). Duration in milliseconds (ms) and amplitude in millivolts(mV) of P waves and QRS complexes, PR and QT segment, T wave amplitude and ST segment were evaluated in leadDII. Using leads I and III, the mean cardiac electrical axis in the frontal plane, expressed in degrees, was determinedas the mean of three consecutive measurements. Values considered normal in Group 1A and 1B for the durantion ofP wave was ≤ 45 ms and QRS duration ≤ 55 ms. In Group 2 the duration of P wave was ≤ 47 ms and QRS duration ≤61 ms. In Group 3 the duration of P wave was ≤ 50 ms and duration QRS ≤ 64 ms. These values (duration of P waveand QRS duration) were compared with echocardiographic measurements of the left atrium, considering the referencevalue AE/Ao ≤ 1.4 and measurements of the left ventricle in M-mode according to the body weight, respectively. AP wave amplitude ≤ 0.4 mV suggested that the right atrium size was normal and this was...

Diagnostic accuracy of the electrocardiogram for detection of atrial and ventricular overloads in dogs

Background: Analysis of the electrocardiogram may suggest atrial and ventricular overloads. However, it has a lowsensitivity and specificity for diagnosis of cardiac chamber overload. The accuracy of electrocardiographic interpretation can be improve using new cut-offs for the duration and amplitude of the electrocardiographic waves. Ourobjective was to evaluate the use of the electrocardiogram in the diagnosis of atrial and ventricular overload, usingechocardiography as the gold standard test for the diagnosis of atrioventricular overload. We aimed to define newcut-off values that would increase the sensitivity and specificity of the electrocardiogram for diagnosis of chamberoverload in dogs.Materials, Methods & Results: Eletrocardiogram records were obtained in 81 dogs divided into 3 groups: Group1A (healthy dogs ≤ 10 kg); Group 1B (dogs ≤ 10 kg with mitral or tricuspid valve disease); Group 2 (dogs weighingbetween 10.1 and 20 kg) and Group 3 (dogs > 20.1 kg). Duration in milliseconds (ms) and amplitude in millivolts(mV) of P waves and QRS complexes, PR and QT segment, T wave amplitude and ST segment were evaluated in leadDII. Using leads I and III, the mean cardiac electrical axis in the frontal plane, expressed in degrees, was determinedas the mean of three consecutive measurements. Values considered normal in Group 1A and 1B for the durantion ofP wave was ≤ 45 ms and QRS duration ≤ 55 ms. In Group 2 the duration of P wave was ≤ 47 ms and QRS duration ≤61 ms. In Group 3 the duration of P wave was ≤ 50 ms and duration QRS ≤ 64 ms. These values (duration of P waveand QRS duration) were compared with echocardiographic measurements of the left atrium, considering the referencevalue AE/Ao ≤ 1.4 and measurements of the left ventricle in M-mode according to the body weight, respectively. AP wave amplitude ≤ 0.4 mV suggested that the right atrium size was normal and this was...(AU)

Cardioprotection stimulated by resveratrol and grape products prevents lethal cardiac arrhythmias in an animal model of ischemia and reperfusion

Purpose: To evaluate the preventive cardioprotective effects of resveratrol and grape products, such as grape juice and red wine, in animal model of cardiac ischemia and reperfusion. Methods: Male Wistar rats orally pretreated for 21-days with resveratrol and grape products were anesthetized and placed on mechanical ventilation to surgically induce cardiac ischemia and reperfusion by obstruction (ischemia) followed by liberation (reperfusion) of blood circulation in left descending coronary artery. These rats were submitted to the electrocardiogram (ECG) analysis to evaluate the effects of pretreatment with resveratrol and grape products on the incidence of ventricular arrhythmias (VA), atrioventricular block (AVB) and lethality (LET) resulting from cardiac ischemia and reperfusion. Results: It was observed that the incidence of AVB was significantly lower in rats pretreated with resveratrol (25%), grape juice (37.5%) or red wine (12.5%) than in rats treated with saline solution (80%) or ethanol (80%). Similarly, incidence of LET was also significantly lower in rats pretreated with resveratrol (25%), grape juice (25%) or red wine (0%) than in rats treated with saline solution (62.5%) or ethanol (75%). Conclusion: These results indicate that the cardioprotective response stimulated by resveratrol and grape products prevents the lethal cardiac arrhythmias in animal model of ischemia and reperfusion, supporting the idea that this treatment can be beneficial for prevention of severe cardiac arrhythmias in patients with ischemic heart disease.(AU)

Eletrocardiografia computadorizada em cadelas com tumores mamários / Electrocardiography in bitches with mammary tumors

The incidence of cancer has increased due to greater longevity of the animals as a consequence of better control of other diseases, improvement of nutrition and good practices in preventive medicine. Malignant tumors can cause paraneoplastic syndrome such as hypercalcemia, anemia, cachexia, among others and consequent cardiovascular disorders. The electrocardiography (ECG) is a complementary exam that can reveal with its traces these rhythmic disorders. Based on that, the objective of this study was to evaluate the ECG in bitches with mammary tumors in order to detect in which type of tumor would be found significant changes as in cardiac rhythm, ECG waves, segments or cardiac axis. Twenty-nine female dogs were used in this study, being 19 bitches with mammary tumor, and they were allocated in three groups: G1: control group (n = 10), G2: benign neoplasia group (n = 6) and G3: malignant neoplasia group (n = 13). The most prevalent type of neoplasia in G2 was the benign mixed tumor (83%), followed by adenoma (17%) whereas in G3: carcinoma in mixed tumor (61%); papillary carcinoma (23%). Regarding cardiac rhythm, it was found sinus arrhythmia (SA) and normal sinus rhythm (NS): G1: 50% SA and 50% NS; G2: 67% SA and 33% NS; G3: 54% SA and 46% NS. No ventricular or atrial arrhythmias were detected. For other parameters in G1, G2 and G3, respectively (mean ± Std error): FC (bpm): 110±9.2, 120 ± 8.5, 124±7,5; P (ms): 48 ± 1.6, 51 ± 1.8, 50 ± 1.2; P (mV) 0.19 ± 0.02, 0.2 ± 0.02, 0.19 ± 0.02; PR (ms): 94 ± 4.3, 93 ± 5.5, 89 ± 3.9; QRS (ms): 56 ± 1.54, 60 ± 4, 62 ± 1.2; R (mV): 1.1 ± 0.06, 1.2 ± 0.24, 0.9 ± 0.13; QT (ms): 203 ± 9.4; 204 ± 7.9; 182 ± 15.6; and cardiac axis (°): 66 ± 6.2, 61 ± 7.9, 70 ± 7.5. There were no significant differences for all cardiac parameters and also for ST interval and T wave morphology. All electrocardiographic parameters found are in accordance with other studies carried out in the canine species. The results regarding tumor types differ from what was found in another study, in which in 18 bitches with mammary tumors, 55% were benign, with prevalence of adenomas (38%) followed by benign mixed tumors, and 45% malignant, with adenocarcinoma prevailing (22%). In another study, it was verified in 63 bitches the predominance of tubular carcinoma (26.56%) and carcinoma in mixed tumors (23.44%). Diverging from the electrocardiographic parameters of this study, a significant difference was found in the R wave amplitude value in the research by Barros et al., (2015) who performed computerized electrocardiography in 50 dogs, not only with mammary neoplasms (55% mammary carcinomas), but also in mastocytomas, lymphomas, benign tumors and other sarcomas. This author found out that the R wave amplitude values of the neoplasia group were lower when compared to the control group. In addition, we suspect that other types of tumors could result in more paraneoplastic syndrome than the mammary neoplasms found in this research. Neoplasms as lymphomas (T cells), apocrine gland anal sac adenocarcinomas, multiple myelomas and thymomas are known as a cause of hypercalcemia of malignancy and histiocytic sarcomas, myelomas, leukemia and lymphomas causing anemia. In conclusion, ECG has no changes in benign or malignant mammary tumors in dogs. However, this fact does not exclude the importance of its performance in pre-anesthetic evaluations. Further studies with a larger sample including the clinical staging of these bitches with a balanced number of animals with low and high staging are suggested.(AU)

Cardioprotective effects of pharmacological blockade of the mitochondrial calcium uniporter on myocardial ischemia-reperfusion injury

Purpose To evaluate whether the attenuation of mitochondrial Ca2+ overload produced by pharmacological blockade of mitochondrial Ca2+ uniporter (MCU) protects the myocardium against injuries caused by cardiac ischemia and reperfusion (CIR). Methods CIR was induced in adult male Wistar rats (300-350 g) by occlusion of the left anterior descendent coronary artery (10 min), followed by reperfusion (120 min). Rats were treated with different doses of MCU blocker ruthenium red (RuR), administered 5 min before ischemia or reperfusion. Results In untreated rats, the incidences of ventricular arrhythmias (VA), atrioventricular block (AVB) and the lethality (LET) induced by CIR were 85%, 79% and 70%, respectively. In rats treated with RuR before ischemia, the incidences of VA, AVB and LET were significantly reduced to 62%, 25% and 25%, respectively. In rats treated with RuR after ischemia, the incidences of VA, AVB and LET were significantly reduced to 50%, 25% and 25%, respectively. Conclusion The significant reduction of the incidence of CIR-induced VA, AVB and LET produced by the treatment with RuR indicates that the attenuation of mitochondrial Ca2+ overload produced by pharmacological blockade of MCU can protect the myocardium against injuries caused by CIR.(AU)

Eletrocardiografia em cadelas submetidas à mastectomia unilateral total / Electrocardiogram in bitches submitted to unilateral total mastectomy

Background: The frequency of oncological diseases in companion animals has increased in recent years, mainly due tothe longer longevity of dogs. The neoplasms are not only open by the presence of the tumor and its location, but also byparaneoplastic syndromes, which are disorders that occur due to the production of substances by the tumor that cause.In addition to causing local changes and damages, oncological diseases may also result in injuries at distant sites, suchas paraneoplastic syndromes, which, if untreated, may result in death of animals. The present study aimed to investigatewhether female dogs with mammary tumors demonstrate electrocardiographic changes, and if so, to investigate whetherthese cease after removal of the tumor, and to relate the type of tumor with the occurrence of arrhythmias.Materials, Methods & Results: Eighteen female dogs, aged between 4 and 14 years, underwent electrocardiogram 24 hprior to undergoing a total unilateral mastectomy. After removal of the tumor, electrocardiograms were again performed 24(M24), 48 (M48), and 72 (M72), as well as 14 days (M14d) after surgery. Histological analysis of the neoplasms showedthat 55% of the tumors were benign, with predominance of adenoma (38%), and 45% were malignant, with predominanceof adenocarcinoma (22%). The following rhythms and arrhythmias were observed: normal sinus rhythm (37.2%), sinusarrhythmia (62.8%), wandering pacemaker (26%), 1st degree atrioventricular block (AVB; 5%), premature ventricularcomplex (PVC; 10%), and T-wave > 25% of R-wave (25%); more than one change could occur simultaneously. Out of theevaluated electrocardiographic parameters, a significant difference was observed in the QT interval between the followingtimepoints: M24 (204 ± 18), M48 (204 ± 22), and M72 (203 ± 23), as well as Mbasal (192 ± 15) and M14d (178 ± 43).Discussion: Regarding the observed rhythms, arrhythmias, and changes, respiratory sinus arrhythmia was the normal predominant... (AU)

Eletrocardiografia em cadelas submetidas à mastectomia unilateral total / Electrocardiogram in bitches submitted to unilateral total mastectomy

Background: The frequency of oncological diseases in companion animals has increased in recent years, mainly due tothe longer longevity of dogs. The neoplasms are not only open by the presence of the tumor and its location, but also byparaneoplastic syndromes, which are disorders that occur due to the production of substances by the tumor that cause.In addition to causing local changes and damages, oncological diseases may also result in injuries at distant sites, suchas paraneoplastic syndromes, which, if untreated, may result in death of animals. The present study aimed to investigatewhether female dogs with mammary tumors demonstrate electrocardiographic changes, and if so, to investigate whetherthese cease after removal of the tumor, and to relate the type of tumor with the occurrence of arrhythmias.Materials, Methods & Results: Eighteen female dogs, aged between 4 and 14 years, underwent electrocardiogram 24 hprior to undergoing a total unilateral mastectomy. After removal of the tumor, electrocardiograms were again performed 24(M24), 48 (M48), and 72 (M72), as well as 14 days (M14d) after surgery. Histological analysis of the neoplasms showedthat 55% of the tumors were benign, with predominance of adenoma (38%), and 45% were malignant, with predominanceof adenocarcinoma (22%). The following rhythms and arrhythmias were observed: normal sinus rhythm (37.2%), sinusarrhythmia (62.8%), wandering pacemaker (26%), 1st degree atrioventricular block (AVB; 5%), premature ventricularcomplex (PVC; 10%), and T-wave > 25% of R-wave (25%); more than one change could occur simultaneously. Out of theevaluated electrocardiographic parameters, a significant difference was observed in the QT interval between the followingtimepoints: M24 (204 ± 18), M48 (204 ± 22), and M72 (203 ± 23), as well as Mbasal (192 ± 15) and M14d (178 ± 43).Discussion: Regarding the observed rhythms, arrhythmias, and changes, respiratory sinus arrhythmia was the normal predominant...

Prognostic value of coupling interval, prematurity index and heart rate variability in Boxer dogs / Valor prognóstico do intervalo de acoplamento, índice de prematuridade e variabilidade da frequência cardíaca em cães da raça Boxer

Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC) can experience sudden cardiac death regardless of presence/absence of clinical signs. The aims of this retrospective study were two-fold: 1) to investigate the coupling interval (CI) and prematurity index (PI) of ventricular arrhythmias (VA), and the heart rate variability (HRV) in Boxers, and 2) to evaluate their impact on overall survival time. The first 24-hour Holter 36 client-owned Boxer dogs meeting inclusion/exclusion criteria were evaluated for the number, morphology, site of origin, complexity, CI and PI, of ventricular premature complexes (VPCs), and time domain HRV. The effect on survival was assessed, considering the presence/absence of ventricular tachycardia (VT), and syncope. All-cause mortality was considered as the end-point, with median survival times being obtained by Kaplan-Meier analyses and compared by log-rank test. Polymorphic VPCs were more common in symptomatic dogs than asymptomatic. VPCs in dogs with VT were less premature, due to the influence of heart rate on PI despite comparable CI. The PI and mean heart rate (HRme) were significantly different between VT and non-VT dogs but did not discriminate adequately between groups as standalone tests. Median survival time was shorter in Boxer dogs with VT (463 vs 1645 days, HR: 4.31, P=0.03). The HRV parameters, SDNN and SDANN, were both associated with prognosis. The CI and PI were not demonstrated to be prognostic surrogates in Boxer dogs with VA. HRme≥112bpm is 100% sensitive but only 46% specific for detecting VT in Boxers on the 24-hour Holter. Presence of VT, SDNN≤245ms, or SDANN≤134ms at the time of the first 24-hour Holter was associated with a shorter survival.(AU)

Cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) podem apresentar morte súbita independentemente da presença/ausência de sinais clínicos. Os objetivos desse estudo retrospectivo foram: 1) investigar o intervalo de acoplamento (IA) e o índice de prematuridade (IP) das arritmias ventriculares e a variabilidade da frequência cardíaca (VFC) em Boxers, e 2) avaliar o impacto de tais características sob o tempo de sobrevida global. O primeiro Holter de 24 horas de 36 Boxers selecionados para os critérios de inclusão/exclusão foram avaliados para o número, morfologia, local de origem, complexidade, IA e IP dos complexos ventriculares prematuros (CVPs) e da VFC no domínio do tempo. O efeito na sobrevida foi avaliado, considerado a presença/ausência de taquicardia ventricular (TV), e síncope. O desfecho final foi a mortalidade global, com o tempo de sobrevida mediano sendo obtido pela análise de Kaplan-Meier e comparado pelo teste de log-rank. CVPs polimórficos foram mais comuns em cães sintomáticos. Os CVPs em Boxers com TV foram menos prematuros, devido à influência da frequência cardíaca (FC) sobre o IP, apesar de IA comparáveis. O IP e a FC média diferiram entre os cães com TV e os sem, mas não discriminam adequadamente os grupos como variáveis isoladas. A sobrevida global foi menor nos cães com TV (463 dias vs 1645 dias, HR=4,31, P=0,03). Os parâmetros da VFC, SDNN e SDANN, foram associados ao prognóstico. O IA e o IP não possuem valor prognóstico em Boxers com arritmias ventriculares. A FC média ≥112bpm é 100% sensível, mas apenas 46% específica para detectar Boxers com TV no Holter de 24 horas. A presença de TV, SDNN≤245ms, ou SDANN≤134ms no momento do primeiro Holter de 24 horas estão associados a menor sobrevida global no Boxer.(AU)

Prognostic value of coupling interval, prematurity index and heart rate variability in Boxer dogs / Valor prognóstico do intervalo de acoplamento, índice de prematuridade e variabilidade da frequência cardíaca em cães da raça Boxer

Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC) can experience sudden cardiac death regardless of presence/absence of clinical signs. The aims of this retrospective study were two-fold: 1) to investigate the coupling interval (CI) and prematurity index (PI) of ventricular arrhythmias (VA), and the heart rate variability (HRV) in Boxers, and 2) to evaluate their impact on overall survival time. The first 24-hour Holter 36 client-owned Boxer dogs meeting inclusion/exclusion criteria were evaluated for the number, morphology, site of origin, complexity, CI and PI, of ventricular premature complexes (VPCs), and time domain HRV. The effect on survival was assessed, considering the presence/absence of ventricular tachycardia (VT), and syncope. All-cause mortality was considered as the end-point, with median survival times being obtained by Kaplan-Meier analyses and compared by log-rank test. Polymorphic VPCs were more common in symptomatic dogs than asymptomatic. VPCs in dogs with VT were less premature, due to the influence of heart rate on PI despite comparable CI. The PI and mean heart rate (HRme) were significantly different between VT and non-VT dogs but did not discriminate adequately between groups as standalone tests. Median survival time was shorter in Boxer dogs with VT (463 vs 1645 days, HR: 4.31, P=0.03). The HRV parameters, SDNN and SDANN, were both associated with prognosis. The CI and PI were not demonstrated to be prognostic surrogates in Boxer dogs with VA. HRme≥112bpm is 100% sensitive but only 46% specific for detecting VT in Boxers on the 24-hour Holter. Presence of VT, SDNN≤245ms, or SDANN≤134ms at the time of the first 24-hour Holter was associated with a shorter survival.(AU)

Cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) podem apresentar morte súbita independentemente da presença/ausência de sinais clínicos. Os objetivos desse estudo retrospectivo foram: 1) investigar o intervalo de acoplamento (IA) e o índice de prematuridade (IP) das arritmias ventriculares e a variabilidade da frequência cardíaca (VFC) em Boxers, e 2) avaliar o impacto de tais características sob o tempo de sobrevida global. O primeiro Holter de 24 horas de 36 Boxers selecionados para os critérios de inclusão/exclusão foram avaliados para o número, morfologia, local de origem, complexidade, IA e IP dos complexos ventriculares prematuros (CVPs) e da VFC no domínio do tempo. O efeito na sobrevida foi avaliado, considerado a presença/ausência de taquicardia ventricular (TV), e síncope. O desfecho final foi a mortalidade global, com o tempo de sobrevida mediano sendo obtido pela análise de Kaplan-Meier e comparado pelo teste de log-rank. CVPs polimórficos foram mais comuns em cães sintomáticos. Os CVPs em Boxers com TV foram menos prematuros, devido à influência da frequência cardíaca (FC) sobre o IP, apesar de IA comparáveis. O IP e a FC média diferiram entre os cães com TV e os sem, mas não discriminam adequadamente os grupos como variáveis isoladas. A sobrevida global foi menor nos cães com TV (463 dias vs 1645 dias, HR=4,31, P=0,03). Os parâmetros da VFC, SDNN e SDANN, foram associados ao prognóstico. O IA e o IP não possuem valor prognóstico em Boxers com arritmias ventriculares. A FC média ≥112bpm é 100% sensível, mas apenas 46% específica para detectar Boxers com TV no Holter de 24 horas. A presença de TV, SDNN≤245ms, ou SDANN≤134ms no momento do primeiro Holter de 24 horas estão associados a menor sobrevida global no Boxer.(AU)

Arritmias no uso da dexmedetomina em cães / Arrhythmias in the use of dexmedethine in dogs

A dexmedetomidina é um fármaco agonista a-2 adrenérgico utilizado na anestesiologia veterinária, devido a suas propriedades sedativas e analgésicas. Existem preocupações quanto aos seus efeitos colaterais, principalmente cardiovasculares, dentre eles arritmias. As quais podem comprometer o débito cardíaco e a perfusão tecidual. As arritmias que podem ser observadas com o uso da dexmedetomidina são: bloqueio átrio ventricular de 1º, 2º e 3º grau; arritmia sinusal, e pausa sinusal. Dentre elas a de maior ocorrência é o bloqueio atrioventricular, principalmente o de 2º grau. Essas alterações são dose-dependentes, estudos demonstram que doses de 1 µg /kg podem desencadear a ocorrência de bradiarritmias. O tratamento das arritmias atrioventriculares envolve a administração de anticolinérgicos, antiarrítmicos e no caso de alterações desencadeadas pelo uso da dexmedetomidina a aplicação de um antagonista a-2 adrenérgico. Esta revisão tem como objetivo discorrer sobre as arritmias em cães ocasionadas pelo uso da dexmedetomidina.

Dexmedetomidine is a α-2 adrenergic agonist drug used in veterinary anesthesiologydue to its sedative and analgesic properties. There are concerns about its side effects, especially cardiovascular, among them arrhythmias. These may compromise cardiac output and tissue perfusion. The arrhythmias that may be observed with the use of dexmedetomidine are: ventricularatrium blockade of 1st, 2nd and 3rd degree; sinus arrhythmia, and sinus pause. Among them, the most frequent occurrence is atrioventricular block, especially the second degree. These changes are dose-dependent, studies have shown that doses of 1 μg/kg can trigger the occurrence of bradyarrhythmias. Treatment of atrioventricular arrhythmias involves the administration of anticholinergics, antiarrhythmics and in the case of changes triggered by the use of dexmedetomidinethe application of a α-2 adrenergic antagonist. This review aims to discuss the arrhythmias in dogs caused by the use of dexmedetomidine.

Arritmias no uso da dexmedetomina em cães / Arrhythmias in the use of dexmedethine in dogs

A dexmedetomidina é um fármaco agonista a-2 adrenérgico utilizado na anestesiologia veterinária, devido a suas propriedades sedativas e analgésicas. Existem preocupações quanto aos seus efeitos colaterais, principalmente cardiovasculares, dentre eles arritmias. As quais podem comprometer o débito cardíaco e a perfusão tecidual. As arritmias que podem ser observadas com o uso da dexmedetomidina são: bloqueio átrio ventricular de 1º, 2º e 3º grau; arritmia sinusal, e pausa sinusal. Dentre elas a de maior ocorrência é o bloqueio atrioventricular, principalmente o de 2º grau. Essas alterações são dose-dependentes, estudos demonstram que doses de 1 µg /kg podem desencadear a ocorrência de bradiarritmias. O tratamento das arritmias atrioventriculares envolve a administração de anticolinérgicos, antiarrítmicos e no caso de alterações desencadeadas pelo uso da dexmedetomidina a aplicação de um antagonista a-2 adrenérgico. Esta revisão tem como objetivo discorrer sobre as arritmias em cães ocasionadas pelo uso da dexmedetomidina.(AU)

Dexmedetomidine is a α-2 adrenergic agonist drug used in veterinary anesthesiologydue to its sedative and analgesic properties. There are concerns about its side effects, especially cardiovascular, among them arrhythmias. These may compromise cardiac output and tissue perfusion. The arrhythmias that may be observed with the use of dexmedetomidine are: ventricularatrium blockade of 1st, 2nd and 3rd degree; sinus arrhythmia, and sinus pause. Among them, the most frequent occurrence is atrioventricular block, especially the second degree. These changes are dose-dependent, studies have shown that doses of 1 μg/kg can trigger the occurrence of bradyarrhythmias. Treatment of atrioventricular arrhythmias involves the administration of anticholinergics, antiarrhythmics and in the case of changes triggered by the use of dexmedetomidinethe application of a α-2 adrenergic antagonist. This review aims to discuss the arrhythmias in dogs caused by the use of dexmedetomidine.(AU)

Prognostic value of coupling interval, prematurity index and heart rate variability in Boxer dogs

ABSTRACT: Boxer dogs with arrhythmogenic right ventricular cardiomyopathy (ARVC) can experience sudden cardiac death regardless of presence/absence of clinical signs. The aims of this retrospective study were two-fold: 1) to investigate the coupling interval (CI) and prematurity index (PI) of ventricular arrhythmias (VA), and the heart rate variability (HRV) in Boxers, and 2) to evaluate their impact on overall survival time. The first 24-hour Holter 36 client-owned Boxer dogs meeting inclusion/exclusion criteria were evaluated for the number, morphology, site of origin, complexity, CI and PI, of ventricular premature complexes (VPCs), and time domain HRV. The effect on survival was assessed, considering the presence/absence of ventricular tachycardia (VT), and syncope. All-cause mortality was considered as the end-point, with median survival times being obtained by Kaplan-Meier analyses and compared by log-rank test. Polymorphic VPCs were more common in symptomatic dogs than asymptomatic. VPCs in dogs with VT were less premature, due to the influence of heart rate on PI despite comparable CI. The PI and mean heart rate (HRme) were significantly different between VT and non-VT dogs but did not discriminate adequately between groups as standalone tests. Median survival time was shorter in Boxer dogs with VT (463 vs 1645 days, HR: 4.31, P=0.03). The HRV parameters, SDNN and SDANN, were both associated with prognosis. The CI and PI were not demonstrated to be prognostic surrogates in Boxer dogs with VA. HRme112bpm is 100% sensitive but only 46% specific for detecting VT in Boxers on the 24-hour Holter. Presence of VT, SDNN245ms, or SDANN134ms at the time of the first 24-hour Holter was associated with a shorter survival.

RESUMO: Cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) podem apresentar morte súbita independentemente da presença/ausência de sinais clínicos. Os objetivos desse estudo retrospectivo foram: 1) investigar o intervalo de acoplamento (IA) e o índice de prematuridade (IP) das arritmias ventriculares e a variabilidade da frequência cardíaca (VFC) em Boxers, e 2) avaliar o impacto de tais características sob o tempo de sobrevida global. O primeiro Holter de 24 horas de 36 Boxers selecionados para os critérios de inclusão/exclusão foram avaliados para o número, morfologia, local de origem, complexidade, IA e IP dos complexos ventriculares prematuros (CVPs) e da VFC no domínio do tempo. O efeito na sobrevida foi avaliado, considerado a presença/ausência de taquicardia ventricular (TV), e síncope. O desfecho final foi a mortalidade global, com o tempo de sobrevida mediano sendo obtido pela análise de Kaplan-Meier e comparado pelo teste de log-rank. CVPs polimórficos foram mais comuns em cães sintomáticos. Os CVPs em Boxers com TV foram menos prematuros, devido à influência da frequência cardíaca (FC) sobre o IP, apesar de IA comparáveis. O IP e a FC média diferiram entre os cães com TV e os sem, mas não discriminam adequadamente os grupos como variáveis isoladas. A sobrevida global foi menor nos cães com TV (463 dias vs 1645 dias, HR=4,31, P=0,03). Os parâmetros da VFC, SDNN e SDANN, foram associados ao prognóstico. O IA e o IP não possuem valor prognóstico em Boxers com arritmias ventriculares. A FC média 112bpm é 100% sensível, mas apenas 46% específica para detectar Boxers com TV no Holter de 24 horas. A presença de TV, SDNN245ms, ou SDANN134ms no momento do primeiro Holter de 24 horas estão associados a menor sobrevida global no Boxer.

Cardiomiopatia dilatada em cães: revisão de literatura / Dilated cardiomyopathy in dogs: literature review

A presente revisão tem por objetivo aprimorar o conhecimento sobre Dilated Cardiomyopathy (DCM) em cães, visando à compreensão dos aspectos clínicos, diagnóstico e tratamento. A DCM é caracterizada por dilatação ventricular, disfunção sistólica e arritmias que podem culminar em insuficiência cardíaca e morte. É a segunda cardiopatia mais frequente em cães, acometendo principalmente animais de grande porte e machos. A etiologia é idiopática, mas alguns genes associados à doença já foram identificados. A manifestação clínica é dividida basicamente em estágios oculto e sintomático. O estágio oculto é caracterizado pela presença de alterações elétricas e/ou morfológicas e ausência de sinais clínicos. Os cães podem apresentar o estágio oculto longo até o desenvolvimento de insuficiência cardíaca de forma aguda ou morte súbita. O estágio sintomático é definido pela presença de insuficiência cardíaca esquerda ou biventricular. O diagnóstico somente é confirmado por meio de ecocardiograma e/ou Holter. Estes exames são considerados padrão-ouro, uma vez que apresentam alta sensibilidade na identificação precoce da doença. Cães de raças predispostas devem ser monitorados anualmente a partir dos três anos de idade. O tratamento tem o intuito de minimizar os efeitos da insuficiência cardíaca, sendo instituído de acordo com a fase em que o animal se encontra. O prognóstico após início dos sinais clínicos é desfavorável. Alguns fatores podem influenciar a sobrevida de forma positiva ou negativa. A realização de exames periódicos é de grande importância para obter o diagnóstico precoce e intervir de maneira a retardar a progressão da doença.

The aim of the present review is to improve the knowledge about Cardiomyopathy dilata (CMD) in dogs, in order to understanding clinical aspects, diagnosis and treatment. CMD is characterized by ventricular dilation, systolic dysfunction, and arrhythmias that may culminate in heart failure and death. It is the second most common heart disease in dogs, affecting mainly large animals and males. The etiology is idiopathic, but some genes associated with the disease have already been identified. The clinical manifestation is basically divided into occult and symptomatic stages. The occult stage is characterized by the presence of electrical and/or morphological changes and absence of clinical signs. Dogs may present the long occult stage to the development of acute heart failure or sudden death. The symptomatic stage is defined by the presence of left or biventricular heart failure. The diagnosis is only confirmed by echocardiography and/or Holter. These exams are considered gold standard, since they present high sensitivity in the early identification of the disease. Dogs of predisposed breeds should be monitored annually from the age of three. The treatment is intended to minimize the effects of heart failure, and is instituted according to the stage in which the animal is. The prognosis after onset of clinical signs is worse. Some factors may influence survival in a positive or negative way. Periodic examinations are great importance to obtain early diagnosis and interpose in order to delay the progression of the disease.

Cardiomiopatia dilatada em cães: revisão de literatura / Dilated cardiomyopathy in dogs: literature review

A presente revisão tem por objetivo aprimorar o conhecimento sobre Dilated Cardiomyopathy (DCM) em cães, visando à compreensão dos aspectos clínicos, diagnóstico e tratamento.  A DCM é caracterizada por dilatação ventricular, disfunção sistólica e arritmias que podem culminar em insuficiência cardíaca e morte. É a segunda cardiopatia mais frequente em cães, acometendo principalmente animais de grande porte e machos. A etiologia é idiopática, mas alguns genes associados à doença já foram identificados. A manifestação clínica é dividida basicamente em estágios oculto e sintomático. O estágio oculto é caracterizado pela presença de alterações elétricas e/ou morfológicas e ausência de sinais clínicos. Os cães podem apresentar o estágio oculto longo até o desenvolvimento de insuficiência cardíaca de forma aguda ou morte súbita. O estágio sintomático é definido pela presença de insuficiência cardíaca esquerda ou biventricular. O diagnóstico somente é confirmado por meio de ecocardiograma e/ou Holter.  Estes exames são considerados padrão-ouro, uma vez que apresentam alta sensibilidade na identificação precoce da doença. Cães de raças predispostas devem ser monitorados anualmente a partir dos três anos de idade. O tratamento tem o intuito de minimizar os efeitos da insuficiência cardíaca, sendo instituído de acordo com a fase em que o animal se encontra. O prognóstico após início dos

The aim of the present review is to improve the knowledge about Cardiomyopathy dilata (CMD) in dogs, in order to understanding clinical aspects, diagnosis and treatment. CMD is characterized by ventricular dilation, systolic dysfunction, and arrhythmias that may culminate in heart failure and death. It is the second most common heart disease in dogs, affecting mainly large animals and males. The etiology is idiopathic, but some genes associated with the disease have already been identified. The clinical manifestation is basically divided into occult and symptomatic stages. The occult stage is characterized by the presence of electrical and/or morphological changes and absence of clinical signs. Dogs may present the long occult stage to the development of acute heart failure or sudden death. The symptomatic stage is defined by the presence of left or biventricular heart failure. The diagnosis is only confirmed by echocardiography and/or Holter. These exams are considered gold standard, since they present high sensitivity in the early identification of the disease. Dogs of predisposed breeds should be monitored annually from the age of three. The treatment is intended to minimize the effects of heart failure, and is instituted according to the stage in which the animal is. The prognosis after onset of clinical signs is worse. Some factors may influence survival in a positive or negative way. Periodic examinations are great importance to obtain early diagnosis and interpose in order to delay the progression of the disease.(AU)

Cardiomiopatia dilatada em cães: revisão de literatura / Dilated cardiomyopathy in dogs: literature review

A presente revisão tem por objetivo aprimorar o conhecimento sobre Dilated Cardiomyopathy (DCM) em cães, visando à compreensão dos aspectos clínicos, diagnóstico e tratamento.  A DCM é caracterizada por dilatação ventricular, disfunção sistólica e arritmias que podem culminar em insuficiência cardíaca e morte. É a segunda cardiopatia mais frequente em cães, acometendo principalmente animais de grande porte e machos. A etiologia é idiopática, mas alguns genes associados à doença já foram identificados. A manifestação clínica é dividida basicamente em estágios oculto e sintomático. O estágio oculto é caracterizado pela presença de alterações elétricas e/ou morfológicas e ausência de sinais clínicos. Os cães podem apresentar o estágio oculto longo até o desenvolvimento de insuficiência cardíaca de forma aguda ou morte súbita. O estágio sintomático é definido pela presença de insuficiência cardíaca esquerda ou biventricular. O diagnóstico somente é confirmado por meio de ecocardiograma e/ou Holter.  Estes exames são considerados padrão-ouro, uma vez que apresentam alta sensibilidade na identificação precoce da doença. Cães de raças predispostas devem ser monitorados anualmente a partir dos três anos de idade. O tratamento tem o intuito de minimizar os efeitos da insuficiência cardíaca, sendo instituído de acordo com a fase em que o animal se encontra. O prognóstico após início dos

The aim of the present review is to improve the knowledge about Cardiomyopathy dilata (CMD) in dogs, in order to understanding clinical aspects, diagnosis and treatment. CMD is characterized by ventricular dilation, systolic dysfunction, and arrhythmias that may culminate in heart failure and death. It is the second most common heart disease in dogs, affecting mainly large animals and males. The etiology is idiopathic, but some genes associated with the disease have already been identified. The clinical manifestation is basically divided into occult and symptomatic stages. The occult stage is characterized by the presence of electrical and/or morphological changes and absence of clinical signs. Dogs may present the long occult stage to the development of acute heart failure or sudden death. The symptomatic stage is defined by the presence of left or biventricular heart failure. The diagnosis is only confirmed by echocardiography and/or Holter. These exams are considered gold standard, since they present high sensitivity in the early identification of the disease. Dogs of predisposed breeds should be monitored annually from the age of three. The treatment is intended to minimize the effects of heart failure, and is instituted according to the stage in which the animal is. The prognosis after onset of clinical signs is worse. Some factors may influence survival in a positive or negative way. Periodic examinations are great importance to obtain early diagnosis and interpose in order to delay the progression of the disease.

Avaliação da variabilidade da frequencia cardíaca (VFC) em cão da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) / Evaluation of heart rate variability (HRV) in a Boxer dog with arrhythmogenic right ventricle cardiomyopathy (ARVC)

Background: Boxer dog cardiomyopathy was initially described by Neil Harpster in 1983 and has received different names. However, several recent studies demonstrated a similarity to the human arrhythmogenic right ventricular cardiomyopathy (ARVC), which led to the name Boxer ARVC. This hereditary disease seems to be linked to a mutation in the gene that codifies the cardiac ryanodine receptor. This mutation leads to an alteration of the calcium cycle in the heart. The analysis of the heart rate variability is an important predictive factor for diagnosing this disease. Therefore, this study aims to report a case of a Boxer ARVC providing electrocardiographic data and heart rate variability.Case: A 11 year-old male Boxer dog, weighting 29.65 kg, was submitted to a heart check-up due to sudden occurrence of fatigue and syncope. At the clinical examination, heart auscultation did not revealed sounds or arrhythmias. The electrocardiogram results presented tachycardia and a regular rhythm with ventricular premature complexes (VPC´s). Ecodopplercargiogram was performed and values were within normal standards. Thus, a dynamic monitoring of 24 h was performed using a Holter monitor. This analysis demonstrated tachycardia in the sinus rhythm, type I second degree sinoatrial block, normal PR interval and normal length of QRS complexes. In addition, severe ventricular ectopy was identified in the following forms: isolated, paired, and nonsustained ventricular tachycardia. The heart rate variability analysis resulted in mean values of 213 ms (SNDD), 132 ms (SDANN), 211ms (rMSSD) and 33.46% (pNN50). Based on these data, Boxer ARVC is the probable diagnosis. However, a ventricular myocardial biopsy necessary to confirm the disease was not performed due to the inherent risk of the procedure. Treatment was performed with sotalol and a commercial feed specially designed for dogs with for cardiac diseases.[...](AU)

Avaliação da variabilidade da frequencia cardíaca (VFC) em cão da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito (CAVD) / Evaluation of heart rate variability (HRV) in a Boxer dog with arrhythmogenic right ventricle cardiomyopathy (ARVC)

Background: Boxer dog cardiomyopathy was initially described by Neil Harpster in 1983 and has received different names. However, several recent studies demonstrated a similarity to the human arrhythmogenic right ventricular cardiomyopathy (ARVC), which led to the name Boxer ARVC. This hereditary disease seems to be linked to a mutation in the gene that codifies the cardiac ryanodine receptor. This mutation leads to an alteration of the calcium cycle in the heart. The analysis of the heart rate variability is an important predictive factor for diagnosing this disease. Therefore, this study aims to report a case of a Boxer ARVC providing electrocardiographic data and heart rate variability.Case: A 11 year-old male Boxer dog, weighting 29.65 kg, was submitted to a heart check-up due to sudden occurrence of fatigue and syncope. At the clinical examination, heart auscultation did not revealed sounds or arrhythmias. The electrocardiogram results presented tachycardia and a regular rhythm with ventricular premature complexes (VPC´s). Ecodopplercargiogram was performed and values were within normal standards. Thus, a dynamic monitoring of 24 h was performed using a Holter monitor. This analysis demonstrated tachycardia in the sinus rhythm, type I second degree sinoatrial block, normal PR interval and normal length of QRS complexes. In addition, severe ventricular ectopy was identified in the following forms: isolated, paired, and nonsustained ventricular tachycardia. The heart rate variability analysis resulted in mean values of 213 ms (SNDD), 132 ms (SDANN), 211ms (rMSSD) and 33.46% (pNN50). Based on these data, Boxer ARVC is the probable diagnosis. However, a ventricular myocardial biopsy necessary to confirm the disease was not performed due to the inherent risk of the procedure. Treatment was performed with sotalol and a commercial feed specially designed for dogs with for cardiac diseases.[...]