Don't touch that horse until you are legally allowed to do so. Don't get a vet out yet.
Horse people are batpoop crazy. Their owner could fly in at the last moment and try to attack anyone who's been around/messed with/treated/fed those horses in order to place the blame on anyone else but themselves.
If that contract is legally binding, then you need to talk to the BO about it before you approach the horse. Never approach a horse without the owner's permission. Ever. The BO might be thrilled that you are willing to do this. Or she may be angry.
THANK YOU. Those are some of my thoughts exactly. My heart really wants to do what I can to help, but I am also trying to be very cautious and careful. People neglect and abuse animals all the time, but good intentions do not protect you from legal action if you mess with someone else's property. I can't believe people on this forum actually try to blame me and tell me I'm a jerk for not immediately shoving my face in someone else's business and taking a serious legal risk. *eye roll* Thank you for being intelligent and offering real world advice. No good deed goes unpunished I guess.