The event itself is staged in the grounds of Castle McGrath, from to-day(Thursday) until Saturday.
The Trials will select an all Ireland team of 15 to qualify for the International and Supreme competitions taking place in Wales.
Organiser and competitor Allistair Lyttle said, "This is the biggest event in the trialling calendar for Ireland. We have more than 150 competitors running over the three days which culminates in a team going through to the International and Supreme competitions in Cardiff in September. This year we have some of the finest handlers competing for a place at the Internationals. The current handling talent in Ireland is well respected at international level and will almost certainly be viewed as the team to beat. Its certainly a significant event because we see competitors coming from north and south of the border and our team competing at the international will be chosen from island wide talent".
Current world champion James Magee will be sitting on the judging panel alongside Tom Gill, one of Co. Mayo's finest trialists.
The event runs 150 single dog trials over the three days, whilst nine competitors will run two dogs at a time.
"This is a particular skill in itself," explained Allistair. "Running two dogs together is a part of the event not to be missed".
The event is set to see more than 2000 visitors coming to the area from all over Ireland.
Additional attractions include a marquee dance on Friday, August 10 with Hugo Duncan and for the younger members of the audience a children's activity area will also be on site.
"This event of course would not be possible without the support of the International Sheep Dog Society, funders including Failte Ireland and Donegal Local Development Company as well as our sponsors FBD Insurance and Balcas," Allistair continues. "These organisations have displayed an overwhelming generosity in their support of this event. In addition we cannot forget that many local businesses have also given some wonderful prizes for the raffle and that this should also be acknowledged.