Sportal.co.nz 20.Jan.2014Getty Images
Toulouse coach Guy Noves has revealed to the French press that the flanker ruptured his bicep during his club's 16-6 Heineken Cup win over Zebre on Saturday.
Those reports are yet to be officially confirmed by the French national team coaches, but should they prove to be correct then the 32-year-old will likely require surgery.
L'Equipe quoted Noves as saying that Dusautoir had suffered a "rupture of a tendon of the right bicep", adding that "he will be out four months".
The news comes as a blow to France coach Philippe Saint-Andre, who is due to cut his preliminary 30-man squad to 23 players ahead of the start of the tournament.
Toulouse coach Guy Noves told France Bleu that Dusautoir's loss was a big blow for the club and for France.
"He probably won't play again with Toulouse this season," Noves said.
"As far as France are concerned, I think he would have recovered for the June tour of Australia."
France is already without Florian Fritz, halfback Morgan Parra and wing Vincent Clerc while young Perpignan wing Sofiane Guitoune is also unavailable through injury.
Guitoune, who made his debut against Tonga in November and has since played one further Test, suffered a ruptured Achilles in his side's 18-36 loss to Gloucester.
France open their campaign against England at the Stade de France on February 1, before a home clash with Italy the following week.