Does horse manure spread in fields cause virus to other horses eating the grass?

Question

Horses that are grazing in a pasture that has been spread with horse manure from other horses can they pick up a virus from it that would cause harm to them

Answer 1

Horse manure should be composted for a year before being spread on any grazing pasture. Not only does horse manure contain a worm population which can contaminate other horses (but not cows or sheep), but horse manure is also very acidic, and will sour the land (making it unpalatable to horses). Horses will NOT eat where horses have defecated. Sheep or cows will clean up the patches horses won't eat, and horses will clean up patches where cows won't eat. Cross grazing them will produce a clean, lush looking field with a good ph level. Horse-sick or horse-sour land needs to be periodically treated with lime to sweeten the ground. This may not need doing (at least not as often) if cross grazed with sheep or cows.