BrendaPie
When a dying scientist tells his nurse to watch out, she thinks it's his illness-stricken mind playing games with him.
What she doesn't realise is that he was part of a team of scientists that, while looking for the 'Miracle Cure of all Miracle Cures', accidentally created a formula that made warmblooded animals carnivorous and rotted their flesh. And that in an attempt to cover up this blunder, they'd dumped the zombie-making substance on some un-claimed, dis-used land, where they had hoped it would decompose without causing any human harm.
Fortunately, no humans ever came near the stuff.
Unfortunately, a small herd of escaped horses did. Being desperate for grass and ignorant of the stench and colour of the food they were eating, they didn't notice the scientists' creation lurking amid the blades of green.
Within days, the herd of five horses had lost their taste for grass, and were now on the hunt.
On the hunt for human flesh.