The £3.5m capture from Celtic is desperate to get off the mark for his new club but accepts he may be forced to delay his return or risk aggravating the problem that's prevented him from making an immediate impact at Boro.
McDonald had a hernia operation in January and feared he may require further surgery to alleviate the nagging pain he's suffered in recent weeks.
Manager Gordon Strachan will be relieved after a specialist confirmed an injection should be sufficient treatment for McDonald, who is now undergoing a spell of rehabilitation before returning to full training.
Boro have failed to score in open play for over 350 minutes and McDonald's prowess in front of goal is exactly what Strachan's side need to keep their play-off hopes alive.
Barry Robson's two spot kicks secured victory over QPR last Saturday and it's been five games since any Boro forward netted.
Nevertheless, Strachan will not rush his star striker back into the fray and will look to Chris Killen, Leroy Lita and Jeremie Aliadiere to lead Boro's goal threat rather than jeopardise McDonald's longterm fitness.
The striker has been restricted to light gym work this week and is due to be assessed ahead of the trip to face Dave Jones' side.
But McDonald is not expected to be risked this weekend and remains doubtful for the visit of table-toppers Newcastle United on March 13.
He is adamant that he will not return to action until he is in a position to fully showcase his goalscoring talents.
It's felt okay since I had the injection hopefully it stays that way and I keep progressing.
It's frustrating because when you join a new club you want to show what you can do, confirmed McDonald.
I did push myself at the start and didn't do myself any favours but I just wanted to get out there and play. The manager has shown faith in bringing me and I wanted to repay that.
But there is no point going out if you are 75 per cent fit and not able to get to the ball that extra second sharper than the guy who's marking you. That can be the difference between you getting a goal and not.
It's been disappointing.
I've not lost confidence about it but it's been getting me down.
So I said right we need to do something about this.' I'd ignored it for a little while but I went to see the specialist and thankfully I don't need another operation and we've gone down the route of having an injection. Hopefully with this week off from the training and doing rehab work, nothing strenuous, there will be no reaction and we can move on.
Whether or not I am ready for Saturday we'll wait and see. It's just a day by day progression.
The most important thing is if it's not this week we'll look towards the Newcastle game. But whenever I come back it has to be 100per cent right this time. That is the most important thing for me and for Middlesbrough.
Boro target George Boyd has moved to promotion rivals Nottingham Forest on a loan until the end of the season.
The attacking midfielder was on Strachan's wanted list after scoring 12 goals for Peterborough this season.
Source: Northern Echo
Source: Northern Echo