Nelson was left with the handler team in Mendentna as he had developed a sore shoulder in the run from Sourdough.
As Allen will be hoping for a very fast final leg he didn't want to risk turning Nelson's shoulder into a major injury so he reluctantly left him with Wes, Mark and Chris. Nelson is a hard charging and pulling dog and Allen will notice his absence.
Nelson had been doing such a great job up until that point but he will be back with his team mates in a few short hours. He will get some rest and extra attention for the next little while to recuperate.