I'm thinking of trying "KetoChlor", which is for dogs, cats, and horses. It's about $20 including shipping for an 8 ounce/236 mL bottle, or $32 for double that size.
It has 1% Ketoconazole plus 2.3% chlorhexidine (an anti-bacterial agent used in mouthwashes). It also has an "anti-adhesive"...