Electrocardiographic findings in dogs with obstructive airway diseases

Cardiac rhythm disorders are diagnosed through electrocardiography, which is an important tool to investigate other systemic conditions that may be related to the cardiac conduction system. Cardiac regulation is controlled by the autonomic nervous system, and in dogs, it is mainly modulated by a parasympathetic action exerted by the vagus nerve, called vagal tone. Increased vagal tone can occur physiologically or pathologically, leading to the occurrence of bradyarrhythmias. However, some studies report that airway diseases can exacerbate this tone, together with the reduction of sympathetic pathway activities. This study aimed to analyze the cardiac rhythms in dogs presenting with electrocardiographic alterations related to respiratory diseases, in connection with the exacerbation of vagal tone. Medical records of animals whose diagnoses involved at least one respiratory condition and who underwent electrocardiographic assessment between March 2017 to March 2021 were compiled. Data obtained were compiled in Microsoft Excel®1 spreadsheets and evaluated using descriptive statistics through the BioEstat®2 software. Pearson’s correlation was used for quantitative data. A correlation between autonomic regulation and vagal exacerbation was observed in cases with obstructive airways diseases.