"Yesterday after a very hard stage we had a long transfer from Sierra Nevada to the north of Spain. Overnight Rohan Dennis developed an upper respiratory tract infection and is not fit to continue racing tomorrow," BMC's team doctor Daniele Zaccaria said in a statement
"Taking Rohan's upcoming goal of the UCI World Championships into consideration, it is in Rohan's best interests to stop now and recover fully before he goes to Norway."
Dennis, who led BMC across the line in their winning opening team time trial and so led the Vuelta for one stage, was targeting Tuesday's stage 16 individual time trial, and was disappointed to have to leave the race.
"I had a bit of a dry throat during the travel after stage 15 and then I woke up in the middle of the night in a full sweat and with a bad throat and it only got worse by this morning," Dennis explained. "It's difficult to pull out now knowing that I'm one of the favorites for the time trial tomorrow. But my priority is getting my health right before the UCI World Championships so I know it's the right thing to do."
Frankiny, who crashed on stage 15, underwent X-rays on his hip.
"X-rays revealed two subtrochanteric fractures on the neck of the femur," Dr Zaccaria said. "Kilian will return to Switzerland tonight and undergo further evaluation to determine whether surgery will be necessary. The nature of Kilian's injuries at this point late in the season means he will not be able to race again this year and will now focus on his recovery in the off season."
The 23-year-old crashed on a short descent early on stage 15 when his front wheel slid out.
"Despite the pain I managed to chase back to the gruppetto and make it to the finish line," Frankiny said. "Sitting and lying down is okay but walking is basically impossible right now. It's really disappointing to have to stop racing here and for the rest of the season. I was really looking forward to finishing my first Grand Tour in Madrid but now I will allow my fractures to recover and get back on the bike as soon as I can to start my off season."
BMC provided an update on Frankiny's condition after the rest day, adding he also suffered a "non-displaced pelvic fracture".
Kilian will undergo conservative recovery in the next six to eight weeks during which time he will gradually return to training, first on the rollers and then on the road, when he is fit to do so," Dr. Max Testa explained. "We will continue to monitor Kilian's recovery during this period but as we have already communicated, Kilian will not race again this season. We expect a full recovery and fortunately the injury will not affect Kilian's preparation for the 2018 season."