Efeitos da acupuntura na variabilidade da frequência cardíaca e no comportamento em cães submetidos ao estresse sonoro agudo

Abstract

The study of autonomic and behavioral responses in dogs subjected to a stress model is crucial at the present time, since animals and humans are constantly subjected to stress in their daily lives. Several stimuli can generate stress in dogs, as areas with crowed of people or animals and sounds of fireworks and thunder. The continuous and repeated exposure to these situations can affect the welfare and health of dogs. The Acupuncture is one of the therapies of Traditional Chinese Medicine (TCM) that targets the prevention and treatment of behavioral and physiological disorders induced by stress, however there are few studies about its efficacy and its mechanisms of action. The present study aimed to evaluate the sympathetic-vagal balance through the analysis of Heart Rate Variability (HRV) and 14 behavioral parameters in response to an acute sound stress in healthy dogs treated with acupuncture. Therefore, we used 24 beagle dogs divided into three groups of 8 animals each: one control group received no treatment (CTL), the second control group received acupuncture treatment at points not corresponding to those used in TCM (NP) and the third group received acupuncture at acupoints VG20, Yintang, PC6, C7 and E36 (ACUP). The treatments lasted 20 minutes and then the animals were subjected to an acute stress model consisting of a sound stimulus (thunders) with intensity of 103-104 dB and duration of 2.5 minutes. The results of HRV analysis showed that during the stress stimulus, acupuncture significantly reduced the LF/HF ratio and the heart rate (HR) compared to NP and CTL. The NP group also had significantly lower LF/HF ratio compared to the CTL during the stress, showing intermediate values between the CTL and ACUP groups. In the behavioral analysis, when compared to CTL group, ACUP showed significantly lower behavioral scores of panting, restlessness, hiding, bolt, startle and escape of the room; and when compared to the NP, ACUP reduced the behavioral scores of hiding, bolt, startle and escape of the room. In addition to reducing significantly the parameters of panting and bolt when compared to the CTL group, the NP group produced intermediate scores between CTL and ACUP groups. The analysis of these data shows that acupuncture treatment promoted reduction of sympatho-vagal balance probably through a sympathetic inhibition associated to parasympathetic stimulation, as well as producing a reduction of behavioral responses of fight and flight characteristics of stress.