One of the ways that you can "lose" a horse is for them to go down for some reason (why is it always either at night and/or raining?) and you are unable to locate them.
There are assorted reasons for any horse to go down, but in the Northern Hemisphere, as the days shorten, grazing becomes poorer and horses can be tempted to try vegetation not ordinarily grazed. Or, another scenario, plants that are okay another time of year build up toxins due to heat and drought stress - Johnson grass is a prime example.
In Shropshire, UK, a man reported his Welsh Cob mare, Ginger missing with a foal at side. He searched as did neighbors. Dr. Gerard Bingham owns the mare and foal.
Subsequently, photos appeared on social media of the body of the horse with the foal nearby in a field of ragwort - a plant known to be poisonous to horses. Naturally, Facebook users were distressed that the horses were even in the field and the assumption was made that the mare had died of ragwort poisoning.
The RSPCA is investigating; however, the body is believed to be too decomposed to be able to accurately determine the cause of death. There may be proseceution pending.
The initial report was made on July 9, but the body was not found until July 30.
http://www.shropshirestar.com/news/2014/08/05/probe-as-stolen-horse-is-found-dead-in-shropshire-field/
