I've seen 'comfort gut' do some pretty impressive stuff to horses!
Hoffmann minerals and levoxine
Electrolytes, joint supplement, calming supplement, hoof supplement, and vitamins
Fasttrack and buteless. And then mare magic and an electrolyte
Electrolytes and fly control (bug off by smartpak) for everyone, two get cortaflex, and one gets a hoof supplement as well (smarthoof ultra).