Abstract

This study investigated the physiological and hematological responses of polo horses to road transportation exposed to high ambient temperatures. Twenty Argentine polo horses were transported by truck for about 20 hours during the hot-dry season. Key physiological variables such as rectal temperature (RT), body surface temperature (BST), heart rate (HR), and respiratory rate (RR), along with hematological indices [packed cell volume (PCV), red blood cell count (RBC), hemoglobin concentration (Hb), platelet count (PLT), and white blood cell count (WBC)], were measured one week before travel, immediately after unloading, and during recovery. Meteorological parameters were recorded to assess environmental impact. Ambient temperature (AT) during unloading exceeded the thermoneutral zone for horses, indicating heat stress. Upon arrival, RR and RT increased beyond normal ranges, reflecting thermoregulatory strain caused by elevated AT and temperature-humidity index (THI). BST across measured body regions rose immediately after transport and decreased after rest. Hematological results showed temporary increases in PCV, Hb, RBC, WBC, and lymphocyte counts, suggesting stress-related physiological adjustments. These findings suggest that prolonged transport in hot, dry conditions results in significant thermal and hematological changes, potentially increasing disease susceptibility. The results highlight the importance of considering environmental factors and implementing effective management strategies to reduce transportation stress in horses.

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