Sadly, you are going to see more of this. With the rising costs of living, alot of people cannot afford to keep their horses anymore, most of the rescue shelters are full and not taking anymore. Good luck finding one that isn't.
In addition, on a sadder note, many of the buyers that used to buy horses for slaughter & export are not doing so because of a new law PETA got passed banning that. It was not an alternative I was in favor of, but it is painless in comparison to starving to death.
Many people, believe that they can turn their horses out to become wild & free just like the mustangs. The problem with this is that most mustangs are descendant from horses that grew up on open ranges. Horses back in the "real" cowboy days and horses that have grown up on open ranches are used to foraging for themselves and know to paw through snow or move on for better food. Horses that have grown up in stables and fed hay or grain by humans all their lives don't, so they will starve. Not only that, you cannot change a horses diet overnight and expect them to do well. A horse, like a human or any other animal, has to have the correct bacteria in their system to digest the food they eat. Otherwise, they starve, even as they eat.
These are animals that will work themselves to death for their owners and they are going to be left to die.
I love horses and always have and hate to see them hurting. It makes me incredibly sad to know what's coming for these wonderful animals. I am lucky, I can keep my horses at home, many people pay board upward of $250/month per horse and that was a going rate 8 years ago. Hay has doubled in price here in the past year, so I am sure board has gone up as well.