Rot Mare

In Lone Star, a horse on the horizon means survival. It means distance covered, supplies carried, the difference between reaching the next settlement and dying in the open. So when a traveler stranded between towns sees that familiar silhouette against the sky, relief hits before reason does. The shape is right. The gait is wrong. By the time the brain catches up to what the eyes already know, the Rot Mare is charging.
  Rot Mares are undead horses, ragged and skeletal, with wild eyes set past bare bone features and mutated claws where the front hooves should be. They carry the zombie infection in their blood, one of the few animal species capable of doing so. They gallop at near-living speed with vision that rivals any predatory animal, and they hunt with a single-minded aggression that makes even experienced survivors hesitate.
  The attack sequence is brutally efficient. A Rot Mare closes distance at full gallop, trampling targets with hooked claws and striking hooves. When its extended jaws find purchase on a limb, they clamp down to the bone. The creature then runs, dragging the victim between its mutated forelegs, tearing flesh against the ground with every stride. Rot Mares hunt alone or in packs, and a full team of undead horses bearing down on a caravan is enough to scatter even armed defenders.
  The sight of one is enough to freeze a person in place. The ragged appearance, the wild dead eyes, the sheer wrongness of a horse that should not be moving, all of it triggers a deep, involuntary terror that survivors must overcome before they can bring themselves to close within melee range. Those who cannot master that fear tend not to survive the encounter.
  Rot Mares range across the Pridelands and Lone Star, haunting the same open plains where living horses once grazed. The cruelest thing about them is the hope they steal. Every distant silhouette that might be salvation might also be a dead thing running at you with jaws that lock onto bone.