ever wondered why horses seem to foam after a ride horses are among the few animals that regulate body temperature through sweating second only to humans in sweat production horse sweat contains a protein called latherin when this sweat meets air or experiences friction it Foams up like soap this foamy sweat is most noticeable under the saddle where friction is highest while it helps cool the horse it can also lead to problems on cold days rapid sweat evaporation can dangerously lower body tempe