Clean and disinfect everything! By this, we mean anything that each horse may come in contact with: floors, buckets, brushes, tack, clothing, hands, stalls, etc.
Take your horse's temperature twice daily. A healthy horse temperature is between 99 - 101.5 degrees fahrenheit.
Observe for clinical signs of illness for 3-5 days prior to the event as well as throughout the entire duration of the event.
Report sick horse
Be sure to report any fevers or signs of clinical illness to a veterinarian for further examination and evaluation.
Keep yourself educated on EHV-1 and biosecurity tips. Clicking this link to USEF Veterinarian Katie Flynn is a great first step!
Separate horses and supplies
Avoid sharing supplies and equipment unless it has been cleaned and disinfected between uses. Avoid communal water. Limit horse to horse and human to horse contact.