Pimobendan improves clinical signs in short term compared to digoxin or placebo in dogs with heart failure due to chronic degenerative mitral valve disease

Background: Chronic degenerative mitral valve disease (CDMVD) continues to be the most common cause of heart failure (HF) in small breed dogs. Pimobendan (PIMO) is a mixed action drug with inotropic and vasodilator properties and is widely used to treat heart disease in dogs. Therefore, PIMO increases cardiac output, reduces both preload and afterload and increases myocardial contractility without increasing energy consumption and myocardial oxygen. Digoxin (DIG) is a cardiac glycoside acting through inhibition of the sarcolemmal Na+/K+ ATPase pump, hence increasing intracellular calcium. It exerts benefi cial effects on left ventricular function, symptoms and exercise tolerance. The purpose of this prospective, randomized, double blind clinical trial was to evaluate the clinical response and QoLQ in heart failure (HF) dogs treated with digoxin or pimobendan in addition to conventional therapy (furosemide and benazepril). Materials, Methods & Results: Inclusion criteria: dogs in class III or stabilized class IV (NYHA). Exclusion criteria: use of positive inotrope and antiarrhythmic, presence of atrial fi brillation, renal or hepatic disease or neoplasia. Thirty three dogs were included and randomly assigned to DIG (n = 11), PIMO (n = 14) and placebo (PL) (n = 8) and followed up weekly. Data was evaluated for days zero, 7, 14 and 28. Increasing score was assigned to each variable depending on worsening of clinical evaluation (history and physical exam, QoLQ and echocardiogram (echo).Three dogs died during treatment due to worsening of HF, one of PL group and two of DIG group; furthermore, one of PIMO group was censored due to worsening of heart failure. There was no signifi cant difference between and within groups for echo and radiography. PL and DIG groups did not show any signifi cant difference throughout the 28 days of treatment. PIMO group showed lower physical exam score and increased early mitral infl ow velocity on day 28. Serum creatinine increased on days 14 and 28 compared to baseline, but within normal limits. The groups were similar within each evaluation day. Discussion: This is the fi rst short term prospective randomized double blind study comparing PIMO to DIG or PL additionally to conventional therapy (ACEi and furosemide) for dogs with HF due to CDMVD. It was observed an early signifi cant clinical improvement in dogs receiving PIMO compared to those receiving DIG or PL. The increase in early mitral infl ow velocity (E-wave) on day 28 for PIMO group is suggestive of diastolic dysfunction improvement, but this is only one variable related to diastolic function. Creatinine concentration increased in PIMO group, although it remained within normal range. In the present study, although all the three groups received furosemide, only PIMO group showed increase in blood creatinine between baseline and days 7 and 28. This result must be explored in later studies. Regarding the exercise intolerance assessment in a QoLQ, it must be aware that the owner evaluation is strongly infl uenced by the level of exercise that the dog is regularly submitted. Considering that most of the times, small breed dogs in a more advanced age is probably more sedentary and this fact surely precludes the owner to assess the exercise capacity. A more objective evaluation of the exercise tolerance should be considered in further clinical trials. Probably because of the small number of animals included in this study, differences in other studied variables were not found. The short-term follow-up of these patients may also have infl uenced the lack of differences among groups. Considering that stronger clinical evidence is needed to guide clinical decisions, longer prospective studies are also needed to compare the effects of DIG and PIMO, as well as to consider the benefi ts of the use or not of DIG associated with PIMO for dogs in HF due to CDMVD.Funding. This project was fi nancially supported by FAPESP - São Paulo Research Foundation, process number 08/57620-2

Assessment of arrhythmias ocurrence and heart rate variability in obese dogs by Holter method

A obesidade é considerada atualmente um dos maiores problemas de saúde em humanos, sendo considerada endêmica entre adultos e crianças. Situação semelhante tem sido observada em medicina veterinária, como conseqüência de um desequilibrio energético que muitas vezes é resultado do tipo de manejo que os animais recebem. É caracterizada pelo acúmulo excessivo de gordura, superando 15% do peso ideal e culmina com várias modificações nas funções orgânicas. Em humanos, sabe-se que o excesso de peso gera alterações na hemodinâmica, no metabolismo, no estado inflamatório, gerando um aumento do volume circulatório, ativação do sistema nervoso simpático e hipertrofia ventricular e levando ao remodelamento cardíaco. As arritmias cardíacas têm sido descritas em indivíduos obesos, geralmente acompanhadas da hipertrofia ventricular esquerda ou da síndrome da apnéia do sono. A disfunção autonômica, avaliada pela redução da variabilidade da freqüência cardíaca, também é observada nos humanos obesos. Não foram encontradas arritmias em estudo com cães obesos no ECG de rotina. O Holter permite um registro contínuo da atividade elétrica cardíaca, enquanto o paciente continua com as suas atividades diárias normais, assim uma das suas principais indicações é a identificação de presença de arritmias que não são detectados pelo eletrocardiograma de curta duração. Desta forma, o objetivo do estudo foi avaliar, pelo método Holter, a presença de arritmias e, pela análise da variabilidade da freqüência cardíaca, avaliar o balanço autonômico em cães obesos. Para isto, foram selecionados 67 cães obesos com escore de condição corporal (ECC) 8 e 9 e 65 cães com peso ideal (ECC=5), pareados por raça/porte, gênero e idade. Os cães obesos não apresentaram alteração no eletrocardiograma de rotina e nem na mensuração da pressão arterial em relação ao grupo controle. No entanto, o grupo obeso, apresentou maior número de extrassístoles ventriculares, discreta hipertrofia de ventrículo esquerdo. Também foram observados menores valores nos parâmetros de variabilidade da freqüência cardíaca, indicando assim, uma disfunção autonômica.Obesity is currently one of the major health problems in humans, and it is considered endemic among adults and children. A similar situation has been found in veterinary medicine, as a consequence of energy imbalance, resulting, most of the times from the management of these animals. It is characterized by excessive accumulation of fat, over 15% of ideal body weight, and culminates with various organic function modifications. In humans, it is known that body weight excess generates changes on hemodynamics, metabolism, inflammatory status, leading to increased circulatory volume, sympathetic nervous system activation, ventricular hypertrophy and leads to cardiac remodeling. Arrhythmias have been described in obese people, generally accompanied by ventricular hypertrophy or sleep apnea. The autonomic dysfunction, assessed by a decrease in heart rate variability, is also observed in humans. Arrhythmias were not observed in a previous study of routine ECG in obese dogs. Holter monitoring allows for the continuous registration of the electrical activity of the heart, while the patient continues the normal daily activities. Therefore, one of the main indications is the identification of the presence of arrhythmias that are not detected by the short duration ECG. The purpose of this study was to assess, by Holter method, the presence of cardiac arrhythmias, and by heart rate variability, to evaluate the autonomic balance in obese dogs. Sixty seven dogs, with a body condition score (BCS) of 8 and 9, and 65 dogs with ideal body (BCS= 5) weight were selected, matched for breed/size, gender and age. The obese dogs did not present changes on the routine ECG and blood pressure measurement, in relation to control group. Despite that, the obese group showed greater number of ventricular extra-systoles and mild left ventricular hypertrophy. There were also lower values of heart rate variability parameters, which indicate an autonomic dysfunction

Assessment of arrhythmias ocurrence and heart rate variability in obese dogs by Holter method

A obesidade é considerada atualmente um dos maiores problemas de saúde em humanos, sendo considerada endêmica entre adultos e crianças. Situação semelhante tem sido observada em medicina veterinária, como conseqüência de um desequilibrio energético que muitas vezes é resultado do tipo de manejo que os animais recebem. É caracterizada pelo acúmulo excessivo de gordura, superando 15% do peso ideal e culmina com várias modificações nas funções orgânicas. Em humanos, sabe-se que o excesso de peso gera alterações na hemodinâmica, no metabolismo, no estado inflamatório, gerando um aumento do volume circulatório, ativação do sistema nervoso simpático e hipertrofia ventricular e levando ao remodelamento cardíaco. As arritmias cardíacas têm sido descritas em indivíduos obesos, geralmente acompanhadas da hipertrofia ventricular esquerda ou da síndrome da apnéia do sono. A disfunção autonômica, avaliada pela redução da variabilidade da freqüência cardíaca, também é observada nos humanos obesos. Não foram encontradas arritmias em estudo com cães obesos no ECG de rotina. O Holter permite um registro contínuo da atividade elétrica cardíaca, enquanto o paciente continua com as suas atividades diárias normais, assim uma das suas principais indicações é a identificação de presença de arritmias que não são detectados pelo eletrocardiograma de curta duração. Desta forma, o objetivo do estudo foi avaliar, pelo método Holter, a presença de arritmias e, pela análise da variabilidade da freqüência cardíaca, avaliar o balanço autonômico em cães obesos. Para isto, foram selecionados 67 cães obesos com escore de condição corporal (ECC) 8 e 9 e 65 cães com peso ideal (ECC=5), pareados por raça/porte, gênero e idade. Os cães obesos não apresentaram alteração no eletrocardiograma de rotina e nem na mensuração da pressão arterial em relação ao grupo controle. No entanto, o grupo obeso, apresentou maior número de extrassístoles ventriculares, discreta hipertrofia de ventrículo esquerdo. Também foram observados menores valores nos parâmetros de variabilidade da freqüência cardíaca, indicando assim, uma disfunção autonômica.Obesity is currently one of the major health problems in humans, and it is considered endemic among adults and children. A similar situation has been found in veterinary medicine, as a consequence of energy imbalance, resulting, most of the times from the management of these animals. It is characterized by excessive accumulation of fat, over 15% of ideal body weight, and culminates with various organic function modifications. In humans, it is known that body weight excess generates changes on hemodynamics, metabolism, inflammatory status, leading to increased circulatory volume, sympathetic nervous system activation, ventricular hypertrophy and leads to cardiac remodeling. Arrhythmias have been described in obese people, generally accompanied by ventricular hypertrophy or sleep apnea. The autonomic dysfunction, assessed by a decrease in heart rate variability, is also observed in humans. Arrhythmias were not observed in a previous study of routine ECG in obese dogs. Holter monitoring allows for the continuous registration of the electrical activity of the heart, while the patient continues the normal daily activities. Therefore, one of the main indications is the identification of the presence of arrhythmias that are not detected by the short duration ECG. The purpose of this study was to assess, by Holter method, the presence of cardiac arrhythmias, and by heart rate variability, to evaluate the autonomic balance in obese dogs. Sixty seven dogs, with a body condition score (BCS) of 8 and 9, and 65 dogs with ideal body (BCS= 5) weight were selected, matched for breed/size, gender and age. The obese dogs did not present changes on the routine ECG and blood pressure measurement, in relation to control group. Despite that, the obese group showed greater number of ventricular extra-systoles and mild left ventricular hypertrophy. There were also lower values of heart rate variability parameters, which indicate an autonomic dysfunction