Efeito de diferentes intensidades de exercício em esteira sobre os parâmetros eletrocardiográficos de cães hígidos / Effect of different intensities of treadmill exercise on eletrocardiographic parameters of healthy dogs

Objetivou-se a padronização de testes de exercício de alta e baixa intensidades em esteira, bem como a avaliação do eletrocardiograma de cães submetidos a esses testes. Para tal fim, sete cães da raça Australian Cattle Dog e quatro da raça Border Collie clinicamente saudáveis foram submetidos a dois testes de exercício em esteira, com pelo menos sete dias de intervalo: T1 - teste de exercício de alta intensidade e curta duração, e T2 - teste de exercício de baixa intensidade e longa duração. A amplitude e a duração de ondas e intervalos foram avaliadas no momento antes do exercício (M0) e nos momentos imediatamente após o término dos testes (MPE) e 30 minutos após (M30). A frequência e o ritmo cardíacos foram avaliados antes dos testes e continuamente por 30 minutos após o término do exercício. Verificou-se diferença significativa somente para a duração do intervalo QT em M30 em T1, além de algumas arritmias, como complexos atriais e ventriculares prematuros isolados em três animais após o teste T1, e em quatro após T2. Os testes de exercício foram adequados para promover estimulação simpática nos cães, contudo não causaram alterações significativas no eletrocardiograma, provavelmente em razão do excelente condicionamento físico dos animais.(AU)

This study aimed to stardardize high and low intensity exercise tests, and evaluate the electrocardiogram of dogs submitted to these tests. Seven clinically healthy Australian Cattle dogs and four Border Collies underwent two exercise treadmill tests, with at least a seven day interval: T1 - high intensity and short duration exercise test, and T2 - low intensity and long duration exercise test. Amplitude and duration of waves and intervals were assessed at resting time before exercise (M0), at immediately after (MPE) and at 30 minutes (M30) after the end of the tests. Heart rate and cardiac rhythm were evaluated before the tests and continuously for 30 minutes after the end of exercise. There was a significant difference only for duration of the QT interval at M30 in T1, and some arrhythmias such as isolated atrial and ventricular premature complexes in three animals after T1 test, and in four dogs after T2. The exercise tests of the present study was suitable to promote sympathetic stimulation in dogs, however did not cause significant changes on the electrocardiogram probably because of the excellent physical fitness of the dogs.(AU)

Características eletrocardiográficas de éguas da raça Crioula em diferentes fases do período gestacional / Electrocardiographic features of Crioulo mares in different pregnancy stages

Pregnancy can cause several physiologic changes in mares, including modifications in cardiac output and heart positioning. Therefore, these changes could influence electrocardiographic parameters in various stages of pregnancy. This study aimed to evaluate the electrocardiogram of Crioulo mares in different pregnancy stages. Nine non pregnant mares (G0), 11 mares at three months (G3), 11 mares at six months (G6) and 11 mares at 10 months of pregnancy (G10) were submitted to electrocardiographic evaluation. There was higher (P= 0,002) heart rate of G10 (60.45±12.16bpm) when compared to other groups (G0=45.67±10.75bpm; G3=44.91±7.91bpm; G6=46.91±9.12bpm), probably because of an increase in cardiac output to uterine perfusion at the end of pregnancy. Normal sinus rhythm was predominant in most of mares of groups G0, G3 and G6, and sinus tachycardia in most of G10 mares. In conclusion, changes in hemodynamics and in cardiac position can influence on the electrocardiogram of pregnant Crioulo mares, but do not cause relevant rhythm or conduction disturbs.(AU)