Termorregulação de cães domésticos (Canis lupus familiaris) durante passeio em ambiente tropical

Abstract

In general, the thermal environment is considered the main factor that affects animal production, as its effects are directly reflected in the productive parameters of these animals. However, in dogs, mostly bred for companionship, the available information is not as clear as to the influence of the thermal environment on the well-being of these animals. Dogs are homeothermic animals, therefore, there must be a balance between the thermal energy originated and the thermal energy lost, so that they can maintain a relatively constant internal temperature. However, they are very sensitive to changes in temperature, and it is extremely difficult to define a thermoneutral zone for this animal species due to the number of existing breeds. However, dogs represent the largest pet population in Brazil, and this is largely due to the ability developed by them to cooperate and help humans, that said, it was proposed to address the factors that affect the thermoregulation of domestic dogs raised in Brazil and evaluate Thermoregulatory responses of domestic mongrel dogs (NDB) during and after walking outdoors with exposure to different levels of solar radiation. The thermoregulation of five dogs (three males and two females) castrated and healthy was evaluated during and after walking outdoors during the three periods of the day: morning, afternoon, and evening. 135 collections were performed, lasting 42 minutes each. Physiological, behavioral, and meteorological variables were collected and all statistical analyzes were performed using R 4.1.0. The results show that with the increase of BGTSun, the regulation of the body temperature becomes more and more difficult for the animal, that no matter how much it has maintained its body temperatures at narrow levels of variation, the costs were reflected in the increase in the RF and in the increase in TSkin. From the development of a thermal comfort index, it was possible to estimate a critical value for RF: 287 breaths per minute, since, from that moment on, there is an increase in the depth of breathing, thus increasing the tidal respiratory volume, which consequently leads to the animal to hyperventilate, causing a disturbance in the gas exchange process. Thus, it is valid to assume that mongrel dogs (NDB) when exposed to high levels of thermal load with direct sun exposure have an expensive expense to keep their body temperatures within narrow levels of variation.