Ferdinand was selected by Roy Hodgson on Thursday for this month's World Cup qualifiers with San Marino and Montenegro, the first time he has been called up by the current England boss since he took charge just before Euro 2012.
The move caught Ferguson by surprise given Ferdinand's long-standing fitness issues. And he is not entirely convinced international duty is the best way forward for the 34-year-old. He said: "I was as surprised as anyone when I heard."
Ferguson added: "I need to speak to the (United) doctor because we prepare Rio Ferdinand in a certain way and there are certain treatments he has to go through.
"He has to make sure he is going to be OK in terms of the number of games he plays. We have been doing that for two years and it has worked. We have to look at all these things before Rio decides (if he joins up)."
If Ferdinand did not report it would be a minor embarrassment for Hodgson given his climbdown from previous statements that he has "moved on" from the Manchester United defender.
"The procedures have been the same all season which has given him fantastic performance levels when he's playing for us," said Ferguson.
"We have to consider that and Rio is considering that. And we'll see what the outcome of that is."
Meanwhile, Ferguson has rejected Rafael Benitez's accusations that he refused to shake hands with the Chelsea manager ahead of last Sunday's FA Cup tie at Old Trafford.
"It is nonsense," said the Scot. "Why would I refuse to shake his hand? I was signing autographs and I never saw him. Why he has said that I have no idea. If he wanted to shake hands he could have stood straight in front of me. It is absolute nonsense."
Source: PA
Source: PA