Variabilidade da frequência cardíaca como indicativo de estresse em cães domiciliados com restrição de espaço

Abstract

The quality of life of domiciled dogs is related to several factors, and when essential well-being conditions are no longer met, stress occurs, activating different mechanisms in the body as a way of adapting to the stressor. Therefore, among other factors, changes to the cardiovascular system related to an imbalance between the sympathetic and parasympathetic autonomic nervous systems may occur. So, this work aimed at the integrated analysis of heart rate variability and well-being of eight dogs, divided into groups with and without space restrictions, in order to determine the influence of space restriction stress by the present methods. The research was conducted at the Superintendency of the University Veterinary Hospital Unit of the Federal University of Fronteira Sul, Campus Realeza - PR for screening and use of the conventional electrocardiogram in three-minute recordings, as well as at the owners' homes for the use of the ambulatory electrocardiogram in 24 hours recordings. The animal welfare was assessed in hospital and home environments, based on the five-domain model. The data obtained were subjected to statistical analysis, being analyzed using the Shapiro-Wilk normality test. Parametric variables were analyzed using the unpaired T test and non-parametric variables using the Mann-Whitney test. The results obtained showed better well-being indices related mainly to the environment (p<0.001) and behavior (p=0.0002) domains in the group of dogs without space restrictions. There was no difference in the minimum, average and maximum heart rate values, as well as in the heart rate variability indices over 24 hours and for periods between the two groups. There was a strong positive correlation between the RRMED indexes (r=0.7509) and mean heart rate (r=0.7908) when comparing 3-minute and 24-hour electrocardiographic recordings. It is understood that the continuous restriction of space brings harm to the different needs of the animals in addition to the reduction in movement, so, the dogs in this group have flaws in relation to well-being, despite not demonstrating changes in their emotional state during the period observed. The results of the heart rate variability analysis may indicate that dogs in the space-restricted group do not have greater activations of the sympathetic autonomic nervous system related to a stressful environment, or there may be habituation to it, not meaning the absence of losses regarding well-being. Likewise, the integration of the autonomic nervous system with other systems makes its interpretation complex, and there is a need for greater understanding of other factors when analyzing heart rate variability related to stress. From this study it is concluded that heart rates and analysis of heart rate variability were not useful to indicate stress in dogs with space restrictions, however, the five domain model was essential to characterize failures in the well-being of dogs that participated in the research.