I've been involved in several cases of horse neglect here in Michigan via The Michigan Horse Welfare Coalition. (Look it up).
It YOU are aware of a neglected horse (no water, hay, severe weight loss or untreated injury, etc) here in Michigan, both YOU and the owner face jail time for animal abuse. Judges have a very dim view of owners, keepers, boarders and neighbors who fail to intercede on the animal's behalf. Check with your local sheriff on what the consequences are. There are quite a few horse rescue and adoption farms around here. Maybe you should contact them. If it's a case of financial hardship, we provide food, shelter at other locations and even transport to foster farms.
News outlets LOVE to advertise and crucify any horse or dog owner charged with neglect or inhumane treatment. I've had local TV stations fly in to see the animals we've seized from boarding stables, dead owners, horse hoarders, city people, meat packers, and mental health patients.