Llanelli Scarlets' former Harlequins back Dafydd James, Bath scrum-half Andy Williams, Saracens prop Ben Broster, Ospreys lock Ian Evans and Cardiff Blues back-row forward Andy Powell have all answered Ruddock's SOS.
Wales suffered a number of injuries during Friday's 11-10 victory over Fiji, with lock Brent Cockbain unlikely to play again this season because of hamstring trouble, while wing Kevin Morgan, prop Chris Horsman and flanker Dafydd Jones are all struggling.
Cockbain, a member of Wales' Grand Slam side last term, requires surgery to repair his hamstring injury.
James, a 2001 British & Irish Lion, will provide cover for Morgan, with Broster on stand-by for Horsman, Williams covering Scarlets scrum-half Dwayne Peel, who has yet to feature in the autumn series, Evans looking set to replace Cockbain and Powell poised to take over from Jones.
"We have called in a group of quality players to train with the squad to compensate for the various injuries we have picked up, and we will take a decision later in the week as to who will join us full-time," said Ruddock.
"Dafydd James comes to us for the first time since I've been in position as head coach, but he brings a wealth of experience at international level.
"We weren't completely happy with his form when he was with Harlequins last season, but he has been starting to look like his old self since returning to Llanelli, and we are pleased to welcome him back into the fold."
James, capped 41 times, last played for Wales in the 43-17 defeat against New Zealand three years ago.
"Andy Williams is a top quality athlete, and we've had our eye on him for a while. Ian Evans is a young man who is a great prospect for the future, and we want to see a bit more of him in the international environment," added Ruddock.
"Ben Broster, meanwhile, performed superbly for us on our summer tour of North America and so he will fit into the squad well, if necessary, and Andy Powell is a quality player who deserves his chance."