Abstract
The autonomic nervous system (ANS) plays a role in the regulation of the cardiovascular system through
sympathetic and parasympathetic modulations, which act in an associated way in the regulation of
homeostasis. This regulation exercised by the ANS is determined by numerous factors including breathing,
stress, temperature, blood pressure and physical activity. Cardiac nerve regulation is influenced by
obesity, but the autonomic response present in this disorder has not yet been elucidated. It is known
that a 10% increase in body fat is able to lead to a decrease in parasympathetic action and an increase in
heart rate. Heart Rate Variability (HRV) allows the evaluation of autonomic heart modulation through
the ventricular depolarization intervals to the electrocardiogram (ECG), and provides information on the
relationship and contribution of the ANS to the neural influence of heart rate control. The objective of
the present study was to evaluate the HRV by means of an electrocardiographic examination in obese
dogs with Body Condition Score (BCS) 8/9 and 9/9, comparing with HRV of the same animals, after
therapy with therapeutic ration in the period of 6 months, as well as the comparison with control group
with lean animals. With the results obtained in the present study, it can be inferred that probably the
imbalance in the autonomic activity due to obesity in dogs is not the same as in humans and that a greater
understanding of this regulation in these animals is necessary, especially considering their vagotonia.
The diet program based on low-calorie ration reached approximately 10% and 20% of weight reduction
after two and six months, respectively. Obesity raises HRV by increasing parasympathetic activity in the
autonomic regulation of the heart in dogs.
