Mare that sweats profusely?

i am leasing a little mare and she sweats like CRAZY! you can take her for a light little hack and she will be drenched in sweat. She is a thoroughbred and is very hot.she is also a hard working show jumper horse. you can canter her like a lap or two each direction and she will already be sweating a lot. today in my lesson, we jumped a course at 1.15m a few times and afterwards she was so sweaty it was as if she was given a bath, she was dripping! Any help? p.s, she gets electrolytes but should i give her a salt lick too to help replace lost minerals?