Opinions differ a lot! When the goal is rapid cooling of horses in very hot humid weather, it looks like 'hypercooling'(whole body washing with ice water) cools horses off more than sponging off limited areas of the body with tepid water. This study used rectal temperature to compare body temperatures. https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.2042-3306.1995.tb04948.x This study compared a specially designed 'cooling blanket' of breathable fabric layers, to 32 liters of 4 degree Celsius water, by using the pulmonary artery temperature. The cooling blanket failed to perform effectively, the cooling bath was better, but the cooling bath didn't keep the body temperature down once walking was resumed. A NOVEL METHOD OF COOLING HORSES AFTER ENDURANCE EXERCISE - UNIVERSITY OF ILLINOIS This study looked at precooling in 13 different studies - trying to cool the horse off before he performs (we use to do this and in the 1992 Olympics some of the riders were infuriated when the security staff did not let anyone wash down the horses before they competed - one rider insisted the guards do it, and they did!). They found 'moderate' evidence that pre-cooling actually happens. I think they are more endorsing washing the body with cold water, and ingesting an 'ice slurry' as a possible alternative. Pre-cooling for endurance exercise performance in the heat: a systematic review "Current evidence indicates cold water immersion may be the most effective method of pre-cooling to improve endurance performance in hot conditions, although practicality must be considered. Ice slurry ingestion appears to be the most promising practical alternative. Interestingly, cooling garments appear of limited efficacy, despite their frequent use." There doesn't seem to be any endorsement of draping the horse in wet towels or using other cooling garments before or after work. Some older(1995) observations from Sally O'Connor: http://useventing.com/sites/default/files/education_committee_notes_6_95.pdf The main point here is that cold water baths do not cause muscle cramping or tying up.