SUMMARY
The aim of the present study was to evaluate the HRV in the brachycephalic races, before and after surgical correction of the stenosis of the nostrils, by means of prolonged electrocardiography, observing the excess of the parasympathetic stimulation regarding the occurrence of bradyarrhythmias and their clinical consequences, and possibility of improvement of the autonomic balancing after the treatment, increasing the quality and life expectancy of these patients. Sixteen dogs with nostril stenosis were included, where the analysis and progression of the HRC findings at different moments before the surgical procedure (day 0) and after the procedure were performed in two moments, 30 and 60 days. The technique of alavestibulplasty was performed and HRV analysis was recorded by means of prolonged electrocardiography. For this examination, the indexes were analyzed in the time domain. Regarding the clinical findings, there was an improvement in the evaluation of the heart and respiratory rate, as well as a reduction in parasympathetic activity, as shown in the bradyarrhythmias. Regarding the HRV indexes in the time domain, rMSSD and SDNN associated with mean heart rate findings, have brought strong indications that the reduction of parasympathetic stimulation is related to the reduction of HRV in these animals. The rMSSD is the HRV index in the domain of the time that early changed can be used as indicator of the increase of the parasympathetic activity caused by the Brachycephalic Syndrome