You need to look at feed with about 11-14% protein, and at least 7% fat. Patriot makes an excellent feed, but in MY OWN OPINION, the fat is not high enough at 6%. Also with corn as their third ingredient, the sweating problem you are talking about is going to be happening! Alot!...Corn provides a high energy ingredient to feed, and a feed with a less amount of fat to provide it, must provide it another way.
So that is how Patriot provides it.
Why don't you try a feed for him like SafeChoice by Nutrena...its a 14/7 feed, very palatable and very easy to digest....especially for a horse his age...
Also...I know that you just got a teeth float like you said...but if the teeth were bad, it does take a while for a horse that has been chewing poorly to form new chewing habits and you might not see the results of a float right away.
Change the feed...make sure you are feeding a good amount of hay....and let me know if this helps.
Thanks,
Laura Schumann
Laura's Ladder To Success Barrel Clinics
www.lauraschumannbarrelracing.com