Hartley not carrying an injury
New Zealand-born hooker Hartley did not take part in Tuesday afternoon's training session, raising doubts about his fitness for the already-crowned Six Nations champions' bid to complete a European clean sweep.
"Dylan's fine. He trained in the morning but was rested for the afternoon session. But he's fine. He's not carrying an injury, he's good. It was a case of monitoring loads and he was rested for the afternoon session," Borthwick said.
The suspicions of Hartley's availability were reinforced when England named Sale hooker Tommy Taylor as a travelling reserve.
Teams for major matches must include two hookers in their matchday 23 and Luke Cowan-Dickie provided bench cover for Hartley during England's 25-21 win over Wales a Twickenham last weekend, after Jamie George was ruled out with a biceps injury.
However, Borthwick said there was nothing unusual in Taylor's call-up.
"For away games, we take travelling reserves and we're taking Tommy [Taylor] for this one. He's going as a travelling reserve, nothing more than that," he added.
Even if Hartley is fit, England could face disruption to their front row if Joe Marler is banned after being cited for elbowing Wales' Rob Evans. Should Marler miss out on the Stade de France clash, Mako Vunipola is set to be promoted from among the replacements, with Matt Mullan moving onto the bench.
"Joe has trained. He trained unbelievably hard yesterday [Tuesday] and those three guys have pushed each other on really well in every session. In that sense, the hearing hasn't been disruptive.
"Matt Mullan has been excellent this Six Nations in everything he's done. I've known Matt for a number of years. In the latter part of my England career he was in the early part of his. Every time he's come to training, he's always been terrifically committed and done his extras.
"He's been very competitive and been terrific. Should we need players or anything else happen we're well prepared for that," Borthwick stated.
Agence France-Presse