Recovery from transport and acclimatisation of competition horses in a hot humid environment.
Authors: Marlin D J, Schroter R C, White S L, Maykuth P, Matthesen G, Mills P C, Waran N, Harris P
Journal: Equine veterinary journal
Summary
# Editorial Summary: Recovery and Acclimatisation of Competition Horses in Hot, Humid Climates Six competition horses aged 7–12 years were transported from Europe to Atlanta and monitored over 16 days of acclimatisation to subtropical conditions (wet bulb globe temperature 27.6°C versus their baseline 22.0°C). The research team tracked physiological responses including bodyweight, thermoregulation, exercise tolerance, and haematological parameters through daily clinical assessment and controlled exercise protocols averaging 72 minutes daily at moderate intensities (predominantly <120 bpm heart rate). Acute transport-induced weight loss of 4.1% recovered within seven days, whilst elevated respiratory rates persisted throughout acclimatisation; notably, core body temperature, resting heart rate and plasma volume remained stable, and white blood cell counts normalised by day 16 despite transient elevation in the first 10 days. These findings demonstrate that healthy, fit horses can successfully acclimate to hot humid environments without pharmacological intervention if allowed adequate post-transport recovery time, gradual work introduction, and appropriate monitoring—a practical benchmark for equine competitors, veterinarians and their support teams when planning international competition or training camps in warm climates.
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Practical Takeaways
- •Allow 7 days minimum for weight recovery after long-haul transport before assessing fitness for competition; monitor water intake carefully as daytime intake increases significantly in hot climates
- •Implement gradual exercise acclimatisation over 16 days with low-intensity work (below 120 bpm) rather than intense training; elevated respiratory rate and WBC counts are expected physiological responses and normalise with time
- •Establish appropriate monitoring protocols including regular rectal temperature, resting heart rate, and blood work; horses can safely acclimatise to hot humid conditions without developing heat illness if managed conservatively
Key Findings
- •Weight loss of 4.1±0.8% bodyweight following long-haul flight required approximately 7 days to recover
- •Respiratory rate increased significantly throughout 16-day acclimatisation period compared with European baseline, but resting temperature and heart rate remained unchanged
- •White blood cell count elevated on days 4 and 10 of acclimatisation but normalised by day 16
- •Horses maintained fitness with exercise averaging 72±12 minutes daily at low intensity (majority below 120 bpm) without development of heat-related illness