Tests are due to be conducted on the B blood sample from Cian O'Connor's Olympic horse at the USA Equestrian Drug Testing and Research Laboratory in New York today.
The laboratory director, Mr Chris Nattrass, will be carrying out the testing of the sample taken from Waterford Crystal, and the results are expected before the end of the week.
It is not yet known when the results will be made public, however.
Dr Bo Helander, secretary general at the International Federation for Equestrian Sports and head of the body's legal department, is on holiday this week and will be at the World Cup qualifying round in Buenos Aires next weekend prior to a two-day top-level FEI meeting in the Argentinian capital.