McDonald was sent off in the 78th minute for a late challenge and manager Jon Brady confirmed on Thursday that the club would appeal.
Brady, pictured alongside assistant manager Frank Sinclair, said: “I’ve seen the incident and Curtis has taken the ball cleanly but their player has rolled around. I hope the referee sees it like that as well.”
Former West Ham United striker Marlon Harewood scored the only goal of the game after two minutes. Brackley never looked like challenging for a point and Brady is demanding that his team finds their level.
According to Brady, the Nuneaton defeat contrasted sharply with last Saturday's 1-0 home win over Harrogate Town on the opening day of the new season.
He added: “As well organised as we were against Harrogate, we were as disjointed against Nuneaton. Our organisation needs to be better but this is a new side and the players are still bedding in.
"They’ve got to find their level but Nuneaton are full-time. Kevin Wilson has recruited well. They’ve got a good mix of youth and experience and they pulled us apart at times."
He added: “Dan Crane kept us in the game with crucial saves because we only had a 20 or 30 minute spell in the second half when we got going.”