Monitoring changes in skin temperature associated with exercise in horses on a water treadmill by use of infrared thermography

Infrared thermography (IRT) was used to assess surface temperature change as an indirect measure of muscle activity and exercise associated changes in blood flow in the working hind limb muscles of horses (n=7) undergoing water treadmill exercise. Three treatments were investigated including the treadmill ran dry (TD), water at the height of the proximal interphalangeal joint (PIP) and water at the height of the carpus (CP). Maximum skin surface temperature was recorded from the region of the semitendinosus muscle during exercise at each water height. There was a significant difference in surface hind limb temperature between exercise on the water treadmill ran dry and with water at the height of the PIP and CP (P<0.0001) with hotter temperatures recorded during the TD treatment. There was a greater increase in surface temperature of the hind limbs from pre exercise to maximum temperature during the PIP and CP treatments when compared to the TD treatment, however, this was not significant (P=0.58). There was no significant difference in surface hind limb temperature found between exercise in water at the height of the PIP and water at the height of the CP. The findings from this study suggest that IRT is able to non-invasively detect muscle activity and associated changes in blood flow whilst horses are exercised on a water treadmill. IRT could potentially be used as an alternative method to assess muscle activity and temperature change in an aquatic environment where existing methods present methodological challenges.     

Control and amount of heat dissipation through thermal windows in harbor seals (Phoca vitulina)

Pinnipeds have to cope with the thermoregulatory demands of their amphibious lifestyle. As they are effectively insulated against heat loss in water by their blubber, they have to bypass the blubber for heat dissipation while staying ashore. In previous studies thermal windows on the body of captive phocid seals have been described as areas of heat dissipation in air. In this study we used infrared thermography (IRT) to examine thermal windows in seals hauling out as well as in training situations, where the first refers to a voluntary and the latter to an induced stay on shore. Furthermore we provide an IRT-based estimate of heat loss through thermal windows in pinnipeds. Hauling out seals developed thermal windows within a few minutes irrespective of environmental conditions. By contrast, seals staying on shore on a trainer's command did not develop thermal windows at all. The calculation of heat loss through thermal windows resulted in considerable values in air, but above all in water, which is energetically disadvantageous as it takes up to four minutes to close thermal windows in water.     

Assessment of pregnancy in the late-gestation mare using digital infrared thermography

The objective of this study was to investigate use of digital infrared thermal imaging (DITI) to determine whether surface temperature gradient differences exist between pregnant and nonpregnant mares as a noncontact method to determine pregnancy status. On the day measurements were collected, each pregnant mare (n = 10; beginning at 292.4 ± 1.4 d of gestation) was paired with a nonpregnant mare (n = 17). Ambient temperature, DITI measurements (left and right flank, wither temperatures [i.e., animal surface control] and background temperature), and rectal temperatures were obtained every 7 d for 5 wk before parturition and for 3 wk after parturition. There were no differences (P > 0.10) in temperature of the left and right side within groups; therefore, data were pooled. Pregnant mares had a higher (P < 0.01) flank temperature than that of nonpregnant mares (36.0 ± 0.2 °C vs. 34.2 ± 0.2 °C, respectively). Moreover, the difference (2.4 °C) in flank temperatures between the pregnant and nonpregnant mares was greater when the ambient temperature was <19 °C. Flank and wither temperatures were positively correlated (R = 0.72; P < 0.01) and were positively correlated with ambient temperature (R = 0.48 and 0.64, respectively; P < 0.01). However, wither temperatures (skin control site) did not differ (P > 0.10) between pregnant and nonpregnant mares. In conclusion, late-gestation mares had higher flank temperatures than those of nonpregnant mares, regardless of environmental conditions, however discriminating abilities were greater when ambient temperature was lower. We inferred that DITI may have value in confirming mid- to late-gestation pregnancies in some species by noncontact means, as observed in the mare.     

Infrared technology for estrus detection and as a predictor of time of ovulation in dairy cows in a pasture-based system

The development and application of an algorithm to assess the ability of an infrared thermography (IRT) device to predict cows in estrus and about to ovulate was investigated. Twenty cows were synchronized using a controlled internal drug release and PGF2α. Vulval and muzzle temperatures were measured every 12 hours from controlled internal drug release insertion to 32 hours after PGF2α treatment and then every 4 hours until ovulation occurred or until 128 hours after PGF2α treatment (whichever occurred first). Thermal images obtained with a FLIR T620 series infrared camera were analyzed using ThermaCAM Researcher Professional 2.9 software. Cows were also monitored for behavioral signs of estrus and color changes of an Estrotect applied to the tail head of each cow 36 hours after PGF2α treatment. Algorithms were developed by adjusting body surface temperature of individual animals for ambient temperature and humidity during each observation period, and were expressed as a deviation from the baseline temperature. Of the 20 cows enrolled in this study, 12 (60%) ovulated. An IRT estrus alert was defined using different thresholds (D = 1 °C, 1.25 °C, and 1.5 °C). Sensitivity and specificity to predict estrus depended upon the chosen threshold level. At a threshold D = 1 °C, the highest sensitivity (92%; n = 11) and the lowest specificity (29%) and positive predictive value (64%) were observed. Conversely, D = 1.5 °C resulted in sensitivity of 75%, specificity of 57%, and positive predictive value of 69%. The mean ± standard deviation intervals between onset and the end of IRT estrus alert to ovulation were 30.7 ± 8.2 and 13.3 ± 7.7 hours, respectively. Ovulation occurred 24 to 47 hours after the onset of the IRT estrus alert for eight out of the 11 ovulated cows (73%). Although the sensitivity of the IRT alert was greater than visual observation (67%) and Estrotect activation (67%), the specificity and positive predictive value were lower than these two aids (i.e., the IRT overpredicted the incidence of ovulation). Results presented indicate that IRT shows some potential as an estrus detection aid; however, further studies investigating the potential to improve the specificity and capturing data throughout entire 21-day reproductive cycles would be worthwhile.     

Comparison between the coat temperature of the eland and dairy cattle by infrared thermography

Little is known about the thermoregulatory response of the eland, a tropical animal often raised in temperate climate. We compared the surface temperature (T_s) of the eland with that of similarly sized Holstein–Friesian dairy cattle at three different ambient temperatures (T_a) to get better evidence about thermal response. The T_s of all body areas (neck, dewlap, trunk, body forepart, barrel, body hind part, forelimb and rear limb) did not differ at T_a 29.2 °C, but at T_a 12.5 °C all the areas of the eland (except the neck) had lower mean T_s than those areas in cattle. At T_a 0.4 °C, only the eland dewlap had a lower T_s and the eland neck had a higher T_s than that in cattle.