Infrared thermography (IRT) is a non-ionizing, non-invasive technique that permits evaluating the comfort levels of animals, a topic of concern due to the growing interest in determining the state of health and welfare of production animals. The operating principle of IRT is detecting the heat irradiated in anatomical regions characterized by a high density of near-surface blood vessels that can regulate temperature gain or loss from/to the environment by modifying blood flow. This is essential for understanding the various vascular thermoregulation mechanisms of different species, such as rodents and ruminants’ tails. The usefulness of ocular, nasal, and vulvar thermal windows in the orbital (regio orbitalis), nasal (regio nasalis), and urogenital (regio urogenitalis) regions, respectively, has been demonstrated in cattle. However, recent evidence for the river buffalo has detected discrepancies in the data gathered from distinct thermal regions in these large ruminants, suggesting a limited sensitivity and specificity when used with this species due to various factors: the presence of hair, ambient temperature, and anatomical features, such as skin thickness and variations in blood supplies to different regions. In this review, a literature search was conducted in Scopus, Web of Science, ScienceDirect, and PubMed, using keyword combinations that included “infrared thermography”, “water buffalo”, “river buffalo” “thermoregulation”, “microvascular changes”, “lacrimal caruncle”, “udder”, “mastitis”, and “nostril”. We discuss recent findings on four thermal windows—the orbital and nasal regions, mammary gland in the udder region (regio uberis), and vulvar in the urogenital region (regio urogenitalis)—to elucidate the factors that modulate and intervene in validating thermal windows and interpreting the information they provide, as it relates to the clinical usefulness of IRT for cattle (Bos) and the river buffalo (Bubalus bubalis).

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The river buffalo is an emerging production species worldwide; indeed, it is overtaking other cattle as a producer of meat and milk in some countries. Though both species belong to the Bovidae family, they show significant anatomical, physiological, and behavioral differences due to their different phylogenetic positions. The river buffalo is a rustic animal that can benefit from low-quality, fibrous forages due to its digestive system, in contrast to beef cattle or dairy cows. Besides, the buffalo cow's reproductive apparatus has fewer cervical muscle rings and a shorter vagina and cervix. This species has maintained its seasonal breeding pattern, also in contrast to Bos indicus and Bos taurus. Even though buffaloes have an inefficient thermoregulating system, scarce hair, and a thicker epidermis, they are more resistant to tropical weather conditions if water for wallowing is available than dairy cows, which in turn adapt better to temperate zones. Due to the morphology of the river buffalo's mammary glands, they produce less milk, while their conical teats with narrower sphincters decrease predisposition to mastitis compared to dairy cows. Thus, the study of the anatomical and physiological differences among river buffalo, Bos Taurus, and Bos Indicus will allow the implementation of strategies to improve the former's productivity while also increasing welfare levels according to the production system in which they are raised.

The objective of this review is to describe and analyze the effect of feathers, hair, and glabrous (hairless) skin on the thermoregulation of domestic and endotherm animals, especially concerning the uses and scope of infrared thermography (IRT), scientific findings on heat and cold stress, and differences among species of domestic animals. Clinical medicine considers thermoregulation a mechanism that allows animals to adapt to varying thermal environmental conditions, a process in which the presence of feathers, hair, or glabrous skin influences heat loss or heat retention, respectively, under hot and cold environmental conditions. Evaluating body temperature provides vital information on an individual’s physiological state and health status since variations in euthermia maintenance in vertebrates reflect a significant cellular metabolism deviation that needs to be assessed and quantified. IRT is a non-invasive tool for evaluating thermal responses under thermal stress conditions in animals, where the presence or absence of feathers, hair, and glabrous skin can affect readings and the differences detected. Therefore, anatomical regions, the characteristics of feathers, hair, glabrous skin such as structure, length, color, and extension, and strategies for dissipating or retaining heat together constitute a broad area of opportunity for future research into the phenomena of dermal thermoregulation in domestic species.

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.