Scientific findings related to changes in vascular microcirculation using infrared thermography in the river buffalo

Abstract

The objective of this review article is to discuss and analyze the most important scientific findings from studies of vascular microcirculation in the river buffalo using infrared thermography (IRT), as well as the thermal windows utilized with this species. The goals are to define the scope and areas of opportunity for IRT use in evaluating physiological processes and identifying potential applications in reproductive events associated with andrological traits in males and the detection of estrus and udder health in females. IRT has allowed the development of diverse perspectives regarding the comparative physiology of events like thermogenesis, peripheral blood flow, respiratory physiology, and mechanisms that reduce body temperature. The case of the river buffalo is no exception. According to the information analyzed, the temperatures of the orbital area, muzzle, and vulva have proven efficient for evaluating thermal comfort, a particularly important aspect of this species given its limited thermoregulating capacity and constant exposure to extreme temperatures. Evaluating scrotal temperature has been revealed as an appropriate tool for evaluating semen quality, while the surface temperature of the udder is useful in assessing mammary development in female buffaloes, two aspects of great zootechnical importance. In future studies, IRT will play a fundamental role in enhancing our understanding of the river buffalo's mechanisms of vascular microcirculation, with applications in productivity and behavior.

Clinical Applications and Factors Involved in Validating Thermal Windows Used in Infrared Thermography in Cattle and River Buffalo to Assess Health and Productivity

“…However, it is suggested that evaluations of infrared radiation in river buffaloes need to consider uncontrolled productive and climatic conditions because, in this species, environmental temperatures and changes in respiratory patterns can alter the thermal response of this window [28]. In addition, but from an anatomical perspective, differences between these species must be considered when examining IRT images since the river buffalo's mammary tissue has more prominent suspensory ligaments and longer keratinized teats [30,75]. Some studies of river buffaloes have questioned the use of this region for detecting mastitis because, according to Machado et al [70], radiometric thermal images of the left and right regions of the rear udder present higher correlations with somatic cell counts compared to anterior sections.…”

“…These conditions exist, for example, in the eye of the orbital region ( regio orbitalis ) [ 34 , 35 ], the auricular pavilion of the ear in the auricular region ( regio auricularis ), or are traversed by large, straight vessels, as in the tail region ( regio caudalis ) of rats. Regions that satisfy these requirements are called thermal windows [ 16 , 30 , 36 , 37 ]. The high density of blood vessels near the dermal surface is critical because modifications of their diameter affect blood flow and change the heat exchange rate in the zone [ 38 ].…”

“…This peripheral vascular and nervous network is known to respond to stressful or harmful stimuli. It is represented in Figure 3 , showing the location of the orbital region in the medial canthus of the eyelids [ 30 , 49 , 50 , 51 ]. These fibers are sensitive to neurosecretion of epinephrine and norepinephrine that promotes vasoconstriction in the capillaries, thus reducing heat exchange rate and functioning as a local thermoregulating mechanism [ 14 ].…”

“…These factors also impede validating these windows, as has been achieved with others [ 29 ]. Nevertheless, the evidence available signals the following regions as potential thermal windows for cattle and river buffaloes: the lacrimal caruncle of the eye in the orbital region ( regio orbitalis ), the muzzle and external nose of the nasal region ( regio nasalis ), the mammary gland of the udder region ( regio uberis ), and the vulva of the urogenital region ( r egio urogenitalis ) [ 30 , 31 ].…”

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“…However, during the bacterial challenge, endothelial cells redirect some of their lactation function by initiating inflammation to protect the underlying tissue from injury. Endothelial cells closely control the passage of plasma components and leukocytes into infected tissue at the start of inflammation [3]. The discovery of the active role of endothelium has led to significant progress in the study of the pathogenesis of cardiovascular diseases [4].…”