Evaluation of thermoregulation of horses (Equus caballus) submitted to two methods of post-exercise cooling, in hot and humid climate conditions, in the Eastern Amazon

Acute whole-body vibration as a recovery strategy did not alter the content of gluteus medius monocarboxylate-transporters, lactatemia, and acidosis induced by intense exercise in horses

Introduction

Several studies have explored alternatives to enhance the performance, health, and safety of sports horses. One promising method involves the use of vibrating platforms (VP), which offer passive exercise stimulation via mechanical oscillations distributed throughout the body. This type of exercise is referred to as whole-body vibration (WBV) and is an emerging strategy for accelerating muscle recovery. This study examined the dynamics of proteins responsible for transporting monocarboxylates (MCT1 and MCT4), and their relationship with lactatemia and acid-base balance in connection with WBV recovery following intense treadmill exercise in horses.

Methods

Eight crossbred horses underwent the standardized exercise test on the treadmill to determine the velocity corresponding to the lactate threshold. This velocity was used to prescribe the external load of the acute intense exercise bout (AIEB), which was performed to recruit rapidly fatigable type II muscle fibers and induce hyperlactatemia and metabolic acidosis. The horses were assigned to three experimental groups in a crossover design, with a 7-day washout period. The treadmill group (TG) actively recovered through low-intensity treadmill walking. The WBV group (WBVG) followed a stepwise recovery protocol on VP, with each step lasting 2 min and the frequencies decreasing in a specific order: 76, 66, 55, 46, and 32 Hz. The sham group (SG) was designated for horses with the VP turned off. All groups experienced a uniform recovery strategy duration of 10 min. Heart rate (HR), rectal temperature (RT), lactatemia, glycemia, acid-base status and electrolytes, strong ion difference (SID), and muscle monocarboxylate transporters (MCT1 and MCT4), were assessed.

Results

AIEB induced positive chronotropic effects, hyperlactatemia and moderate metabolic acidosis in all experimental groups. All groups also showed transitory hyperthermia, hyperglycemia, hypernatremia, hyperchloremia, hyperkalemia and SID reduction. HR was higher in TG than in the WBVG and SG immediately after the recovery procedures. Between the groups, there was no change in RT, lactatemia, glycemia and MCT1 and MCT4 content. Regardless of groups, the MCT4 content decreased 3 and 6 h after recovery strategies.

Discussion

It was concluded that a single whole-body vibration session did not enhance recovery of lactatemia or acid-base balance in horses after intense treadmill exercise.

Association of Environmental Temperature and Relative Humidity with Ocular and Flank Temperatures in Dromedary Camels

Heat stress represents significant challenges for livestock, adversely affecting their production, reproduction, and overall welfare. This study aimed to explore the interrelationships between environmental and animal-related factors and the flank temperature (FT) and eye temperature (ET) recorded using IRT in dromedary camels. This study was conducted in the Cholistan Desert in 2023, and IRT images of the eyes and flanks were captured from 510 camels across 54 herds. During the image analyses, pictures taken from 499 camels were of good quality and included. The camels were of both sexes and of various ages (minimum 3 years, pubertal and adult stages), and they had diverse physiological statuses (breeding, immature, lactating, non-lactating, and pregnant). Before taking the IRT pictures, ambient temperature and humidity were registered using a weather station, and light intensity was recorded using a lux meter. The ET was associated only with physiological status (p < 0.05), with pregnant females showing the lowest values, while no effects of physiological status, sex, or age were found for FT. The environmental temperature showed a positive correlation with both ET (r = 0.7887) and FT (r = 0.6280), highlighting the sensitivity of camel thermoregulation to temperature fluctuations. As expected, a strong positive correlation between ET and FT (r = 0.6643) was found. Conversely, a significant negative correlation was observed between humidity and ET (-0.7444) and FT (-0.5519), indicating that higher humidity levels lead to decreased temperatures in both regions. Light intensity (lux) exhibited minimal influence on both temperatures, with correlations of 0.1019 for ET and 0.2650 for FT. This study contributes to the field of precision livestock farming by suggesting a possible application of IRT for detecting thermal stress in camels in pastoral settings.

Influence of Loading Density and Gender on the Welfare and Meat Quality of Horses During Transport for Slaughter

The aim of this study was to determine the effects of loading density and gender on blood welfare indicators, carcass bruises and horsemeat quality. Data were collected from twelve transports of 89 slaughter horses originating from the same collection centre. The transportation of slaughter horses at high loading densities (>200 kg/m2), especially stallions, resulted in increased levels of lactate (p = 0.021), glucose (p < 0.0001), ceruloplasmin (p < 0.0001) and AOPP (p < 0.0001), but lower GSH levels (p < 0.0001). Compared to stallions and mares, geldings subjected to high loading density (>200 kg/m2) during transport had lower levels of the aforementioned blood metabolites. In addition, stallions exposed to a high load density (>200 kg/m2) had the highest frequency of severe (p = 0.0002), large (p < 0.0001) and circular (p = 0.0001) carcass bruises, which were predominantly located on the abdominal (p = 0.0056) and thoracic (p = 0.0004) wall. In contrast, a higher percentage (p < 0.0001) of undamaged carcasses was found in slaughter horses exposed to a low loading density (≤200 kg/m2) during transport. Stallions exposed to high loading densities (>200 kg/m2) during transport had the highest initial pH (p < 0.0001) and ultimate pH (p = 0.005) in terms of m. longissimus lumborum and redness (p = 0.017), but the lowest drip loss (p = 0.050) and lightness (p < 0.0001), which, consequently, led to the highest (p = 0.0045) proportion of DFD-like defects in the meat quality. In conclusion, the results of this study showed that high loading densities (>200 kg/m2), regardless of gender, negatively affect horse welfare during transport. In addition, stallions were more sensitive to poor pre-slaughter conditions and produced the lowest meat quality, while geldings were the most resistant. To determine the optimal transport density, further research is needed to determine the effects of different loading densities on the behaviour, physiology, carcass and meat quality of slaughter horses.

Correlation of udder thermogram and somatic cell counts as a tool for detection of subclinical mastitis in buffaloes

This study aimed to monitor the mammary health of 37 multiparous Murrah buffaloes through infrared thermography (IRT). Based on the California Mastitis Test (CMT) and milk somatic cell counts (SCC), buffaloes were grouped into healthy (H, n = 16), subclinical mastitis (SCM, n = 10), and clinical mastitis (CM, n = 11). Buffaloes were milked twice daily in the morning (5:00-6:00 AM) and evening (5:00-6:00 PM). Rectal temperature and respiratory rates were recorded, CMT was performed and thermal images of the mammary gland of all the buffaloes were taken before and after each milking. Milk samples were analysed after each milking for SCC, fat, Solids-Not-Fat (SNF), density, protein, lactose, salts, conductivity, and pH immediately in the laboratory from fresh milk samples. The surface temperature of the periocular region of both the eyes, muzzle, flank, and vagina were also taken. Thermal images were used to assess the surface temperature of the udder (USST), teat apex (TAT), teat barrel (TB1T), teat base (TB2T), and teat skin surface (TSST). Eye and USST showed significantly higher temperatures (p < 0.05), whereas skin surface temperatures (SST) of different body parts were non-significant in both SCM and CM animals than buffaloes in the H group. Milk SCC showed a positive correlation with conductivity (r > 0.7), salts, and pH (r < 0.6) and a negative correlation with fat, SNF, density, protein, and lactose. TAT, TB1T, TB2T, TSST, and USST were positively correlated with milk SCC. Receiver Operating Characteristic (ROC) analysis of H and SCM groups showed that USST before milking had optimum sensitivity (Se = 0.80) and specificity (Sp = 0.906) among the various skin temperatures recorded. Thermal images captured during the morning showed higher sensitivity compared to images taken in the evening. Results indicate IRT can be used to monitor the mammary health of buffaloes but using IRT in conjunction with milk SCC can help in the accurate prediction of SCM in dairy buffaloes.

Functional infrared thermography imaging can be used to assess the effectiveness of Maxicam Gel® in pre-emptively treating transient synovitis and lameness in horses

Introduction

Diagnosing and treating lameness in horses is essential to improving their welfare. In equine orthopedic practice, infrared thermography (IRT) can indirectly detect soreness. Non-steroidal anti-inflammatory drugs can treat painful and inflammatory processes in horses. Using IRT, the efficacy of meloxicam (Maxicam Gel®) was evaluated in pre-treating transient synovitis in horses induced by a middle carpal joint injection of lipopolysaccharides (LPS) from E. coli 055:B5 at a dose of 10 endotoxin units.

Methods

In a cross-over design, six healthy horses were randomly assigned to receive either 0.6 mg/kg of oral Maxicam Gel® (MAXVO) or a mock administration (control group, C) following a two-week washout period. IRT of the middle carpal joint, visual lameness assessment and joint circumference were recorded over time. Clinical and hematological evaluations were performed. Synovial fluid aspirates were analyzed for total nucleated cell count, total protein, and prostaglandin E2. A mixed effects analysis of variance was performed for repeated measures over time, followed by Tukey's test. A multinomial logistic regression was conducted to determine whether there is a relationship between a thermography temperature change and the lameness score.

Results

There were no changes in joint circumference. The MAXVO group showed a lower rectal temperature 4 h after synovitis induction. The C group presented an increase in neutrophils and a decrease in total hemoglobin and hematocrit 8 h after induction. No changes were observed in the synovial fluid between groups. The horses that received meloxicam did not show clinically significant lameness at any time, while the C group showed an increase in lameness 2, 4, and 8 h after synovitis induction.

Discussion

IRT indicated that the skin surface temperature of the middle carpal joint was lower in horses who received meloxicam, suggesting a reduction in the inflammatory process induced by LPS. It was observed that the maximum temperature peaks in the dorsopalmar and lateropalmar positions can be utilized to predict the severity of lameness, particularly when the temperature rises above 34°C. Horses pre-treated with meloxicam showed either reduced or no indication of mild to moderate pain and presented a lowehr thermographic temperature, which indicates the effectiveness of Maxicam Gel® as an anti-inflammatory.

The Welfare of Horses Competing in Three-Barrel Race Events Is Shown to Be Not Inhibited by Short Intervals between Starts

Equestrian sports require precise animal welfare and health evaluations. To test the hypothesis that horses maintain their welfare when subjected to two three-barrel (3TB) races with 2 min intervals, an experiment was designed to evaluate their surface temperature using infrared thermography (IRT) in regions of interest (barrel, flank, neck, jaw, corner of the mouth, and ocular caruncle) and also measure blood biomarkers (hemogram, total plasma protein, fibrinogen, urea, creatinine, GGT, CK, cortisol, IL-6, and IL-1β). Ten Quarter Horses were monitored through thermography (pre-race, +1, +4, and +24 h post-race) and blood sampling (pre-race, +1, +4, and +24 h post-race). ANOVA and Tukey test at 5% were used. IRT in six regions of interest (Left/Right-barrel, flank, neck muscles) increased at +, with no differences between values recorded at +1 and +4 when compared to those measured pre-race (p > 0.05). Plasma protein, RBC count, hemoglobin, hematocrit, WBC count, neutrophils, and lymphocytes (p < 0.05) increased immediately after the races, with recovery at +1 h. Other biomarkers did not change, including cortisol, IL-6, and IL-1β (p > 0.05). Results indicate that well-conditioned 3TB horses subjected to two races at short intervals do not show changes that could be related to impaired health or welfare.