"His fiancee Michelle and their two sons are now at his bedside at Middlemore Hospital.
"We are still very worried for Hoani and we are continuing to work with Rugby Southland to support Hoani and his family and to support the team who have now returned home."
Rugby Southland general manager Brian Hopley said the "small, very close-knit organisation" was being regularly updated on MacDonald's condition.
The Southland Stags arrived back in Invercargill this morning where they were met at the airport by Rugby Southland staff.
"It's been a very difficult time for the players," Hopley said.
"Hoani has been in our setup for a number of years and some of the players have had lengthy involvements with him both as a team mate and personally.
"Hoani holds a very special place in our organisation and staff and players are supported through this period and their wellbeing is a top priority for us."
MacDonald was understood to have "flatlined" twice after he fell to his knees and had a seizure minutes before half time during yesterday's game.
Pukekohe Volunteer Fire Brigade's senior station officer Graeme Wilson said MacDonald was talking to the team doctor when he had a "fit" and fell unconscious.
His condition deteriorated rapidly and he went into cardiac arrest just minutes after being stretchered off the field.
"It was pretty scary and definitely life-threatening for a while," Mr Wilson said.
"I could tell by the anxiety of the ambulance officers."
Ambulance officers used a defibrillator on MacDonald after CPR and a shot of adrenaline failed to bring back his pulse.
Yesterday, Southland head coach David Henderson said: "As coaches, we knew he was in some serious trouble before half time."
They had tried to shield the team to stay focused on the game so the medical team could do their work and play could continue.
"The Counties medical team were really helpful too," Mr Henderson said.
"Obviously in this situation everyone works together."
Henderson said MacDonald had previously been fit and healthy.
"There was nothing wrong with him. He's a great team man. He's very much a family man with two young kids."
He said all the team wanted was to make sure that MacDonald pulled through. "That's our focus at the moment."
