Obesity is one of the most frequent nutritional problems in companion animals and can lead to severe health problems in dogs and cats, such as cardiovascular diseases. This research aimed to evaluate the structural and functional cardiac changes after weight loss in obese dogs. Eighteen obese healthy dogs were assigned into three different groups, according with their initial body weight: Group I (dogs up to 15 kg), Group II (dogs weighing between 15.1 and 30 kg), and Group III (dogs weighing over 30 kg). The animals were submitted to a caloric restriction weight-loss program until they lose 15% of the body weight. The M-mode echocardiogram, electrocardiogram, and blood pressure evaluations were performed before the diet has started and after the dogs have reached the target weight. Data showed a decrease in left ventricular free wall thickness during diastole and systole in Group III, decrease in the systolic blood pressure in Group III, and also in the mean blood pressure in Group II. It was possible to conclude that the weight loss program can reverse structural cardiac changes such as left ventricle eccentric hypertrophy in dogs weighing more than 30 kg, and decrease the arterial blood pressure in obese dogs.

Pesq. Vet. Bras. 32(Supl. Electrocardiography can be used to quantify the training and athletic performance as well as evaluating the cardiac function under the effect of exercise identifying the influence of cardiac anomalies, and deleterious effects of stress ahead of heart function. Considering the complexity of the physical efforts inherent in polo ponies in competitions, together with the lack of reports in the literature, on the demand resulting for heart. The aim of this study was to identify and evaluate the cardiac effects of electrocardiographic exercise in polo horses in order to support data for understanding the physiological cardiac demand of this sport. We evaluated 27 equine practitioner polo at rest and between five and ten minutes after exercise. The results showed that the observed changes in the duration and P wave amplitude and duration of PR and QT interval were considered in physiological response to increased heart rate. The diphasic P wave found at rest and when atrial hypertrophy represented bifida represented different points of activation of the sinoatrial node. As expected, the QRS complex has not undergone major changes. The ST-segment elevation and T wave changes observed after exercise could pose adverse effects to the myocardium, but studies examining multiple factors are needed to confirm this association and define your actual question. The increase in QTc suggested fatigue mild myocardial represented high heart demand for this type of exercise. The heart score showed that these animals were within the pattern of cardiac adaptation to a horse athlete. The rapid recovery of HR showed good conditioning of these animals. The pacemaker migration was observed in most animals proven to be a normal finding horse athlete. We observed a low incidence of changes in cardiac rhythm.INDEX TERMS: Cardiac function, electrocardiographic index, physiology exercise.

RESUMO.-[Caracterização clínica da cardiomiopatia chagásica crônica em cães.] No continente Americano, aproximadamente 15 milhões de pessoas são afetadas pela doença de Chagas, ocasionando importantes danos econômicos e sociais. O cão é considerado excelente modelo experimental para o estudo dessa enfermidade; assim sendo, foram caracterizadas, neste ensaio, as anormalidades cardiovasculares de 13 cães experimentalmente infectados com a cepa Colombiana do Trypanosoma cruzi, em fase crônica (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004). Ao eletrocardiograma, a arritmia sinusal respiratória foi o ritmo predominante durante todo período experimental (49,55-67%), com baixas prevalên-cias de bloqueio de ramo direito (0-13%) e de bloqueio atrioventricular de primeiro grau (0-14%). A EcoDopplercardiografia espectral revelou inversão das ondas E e A mitral (0.71±0.17), confirmando a disfunção diastólica presente em todos os cães avaliados. O aumento da atividade enzimática sérica foi detectado, indicando agressão miocárdica pela infecção. Seis cães morreram durante o perí-odo experimental. Desta forma, a caracterização clínica dos cães experimentalmente infectados trouxe informações importantes, possibilitando reconhecer o comportamento clínico dessa importante infecção, na espécie canina.

Early identification of arrhythmias in dogs showing doxorubicin-induced cardiomyopathy was studied. Ten healthy dogs were assigned to groups A (n=5) and B (n=5). Dogs from group B were given doxorubicin 30mg/m 2 intravenously, every 21 days, until a cumulative dose of 180mg/m 2 or 240mg/m 2 was reached. Dogs from group A (used as control) were administered saline intravenously at the same group B intervals. As soon as myocardium dysfunction was observed in dogs from group B, determined by a shortening fraction below 20%, increased E-point to septal separation above 0.7cm, and increased end-systolic left ventricular volume index (61.4ml/m 2 ), a 24-hour Holter was recorded in all dogs from both groups. There was an increase of minimum heart rate (44.6%) and mean heart rate (41.7%) in animals from group B in comparison with the control animals. Either supraventricular or ventricular arrhythmias were observed, despite group B dogs showed higher occurrence of supraventricular arrhytmias. Holter monitoring is efficient in early determination of heart rate and cardiac rhythm alterations in dogs showing doxorubicin-induced myocardial dysfunction.Keywords: dog, doxorubicin, eletrocardiogram, cardiopathy RESUMO O estudo consistiu na identificação precoce da ocorrência de arritmias em cães com cardiomiopatia dilatada experimental induzida pela doxorrubicina (DOX). Utilizaram-se 10 cães adultos, sadios, distribuídos nos grupos A (n=5) e B (n=5

The aim of this study was to evaluate the hemodynamic and acid-base status of dogs subjected to acute normovolemic anemia. The dogs (n = 10) were evaluated 15 minutes and 24 hours after induction of anemia (hematocrit below 18%) with blood withdrawal and simultaneously replacement of same volume of Ringer's lactate solution and hydroxyethyl starch-based solution in a 2 : 1 ratio. The cardiac output was measured by Doppler echocardiography and blood pressure by oscillometric device, and posteriorly hemodynamic parameters were calculated. The anemic groups had increase in cardiac index (P < .05) (3.82 ± 1.05 to 5.86 ± 1.49 and 5.81 ± 1.63 L/min × m2) and decreases (P < .05) in the indices of total peripheral resistance (6797.81 ± 3060.22 to 3220.14 ± 1275.02 and 3887.74 ± 1394.89 dina·seg/cm5 × m2) and oxygen delivery (7942.84 ± 3344.00 to 4021.68 ± 1627.00 and 4430.82 ± 1402.61 mL/min × m2), respectively. There were no significant changes in pH, but PaO2 and SaO2 values were increased, and PaCO2 reduced in anemic dogs (P < .05). Therefore, acute normovolemic anemia can create significant hemodynamic changes and despite some hemogasometric changes, there were no changes in the acid-base status in dogs.

The effects of inspired oxygen fractions (FiO2) of 1 and 0.6 on bispectral index (BIS) in dogs with high intracranial pressure, submitted to a continuous rate infusion of propofol were evaluated. Eight dogs were anesthetized on two occasions, receiving, during controlled ventilation, an FiO2 = 1 (G100) or an FiO2 = 0.6 (G60). Propofol was used for induction (10mg.kg-1, IV), followed by a continuous rate infusion (0.6mg.kg-1.minute-1). After 20 minutes, a fiber-optic catheter was implanted on the surface of the right cerebral cortex to monitor the intracranial pressure, the baseline measurements of BIS values, signal quality index, suppression ratio number, electromyogram indicator, end-tidal carbon dioxide partial pressure, mean arterial pressure, intracranial pressure and cerebral perfusion pressure were taken. Then, the blood flow from the right jugular vein was interrupted in order to increase intracranial pressure and after 20 minutes additional recordings were performed at 15-minute intervals (T0, T15, T30, T45 and T60). The arterial oxygen partial pressure varied according to the changes in oxygen. For the other parameters, no significant differences were recorded. The BIS monitoring was not influenced by different FiO2.

Blood parasitosis is a frequent cause of anemia and myocarditis in dogs. Because anemia can trigger hypoxia or hemodynamic disturbances and myocarditis secondary to blood parasitosis can develop arrhythmias, electrocardiogram changes and increased levels of cardiac biomarkers, such as cardiac troponin I, are expected in dogs with blood parasitosis. Thus, this study aimed to investigate the electrocardiographic characteristics and the relationship to troponin I levels in anemic dogs with blood parasitosis. Twenty-eight dogs with blood parasitosis (seropositive for Ehrlichia canis/ Babesia canis) and varying levels of anemia were evaluated. Dogs with very severe anemia (hematocrit below 13%) showed significant increases in heart rate when compared to dogs with severe, moderate or mild anemia. There was a predominance of respiratory sinus arrhythmia in dogs with mild, moderate and severe anemia and a high prevalence of sinus rhythm in dogs with very severe anemia, which showed a decrease in parasympathetic activity in this group. In all of the groups, electrocardiographic changes were detected showing compatibility with left and right atrial and left ventricular enlargement. Dogs with very severe anemia had a longer P wave duration. All groups of anemic dogs showed increased T-wave amplitude, suggestive of myocardial hypoxia. However, only the groups with moderate and severe anemia presented ST segment disturbances. Despite the lack of a correlation between the electrocardiographic changes suggestive of myocardial hypoxia and troponin I, there was a negative correlation (r = -0.95, p = 0.05) between hemoglobin levels and increased serum troponin. These data indicate that anemic dogs with blood parasitosis may have electrocardiographic changes suggestive of atrioventricular overload or hemodynamic disturbances, such as increased heart rate. Moreover, the negative correlation between hemoglobin and serum levels of troponin I may imply that dogs with severe and very severe anemia are at a higher risk for myocardial injury. Key words: Cardiac biomarker, electrocardiogram; hematocrit, myocardial hypoxia ResumoHemoparasitoses são causas frequentes de anemia e miocardite em cães. Em virtude da anemia poder provocar distúrbios hemodinâmicos relacionados à hipóxia e da miocardite secundária à hemoparasitose causar arritmias cardíacas, esperam-se alterações eletrocardiográficas e aumento dos níveis de biomarcadores cardíacos como troponina I cardíaca em cães com hemoparasitose. Por conseguinte, este estudo teve como objetivo investigar as características eletrocardiográficas de cães anêmicos por hemoparasitose e a relação da anemia com alterações eletrocardiográficas e aumento da troponina I cardíaca. Para tanto, foram avaliados vinte e oito cães com hemoparasitose, sorologicamente positivos para Ehrlichia canis/ Babesia canis, com diferentes níveis de anemia. Cães com anemia muito grave (hematócrito abaixo de 13%) apresentaram aumentos significativos da frequência cardíaca, comparados aos cães com anemia grave, mode...

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