When we rescued Darwin he was a year old and had been living in a flat in London.
While his owners did thier best the poor pup was just getting stressed at being cooped up all day on his own.
As a result of the stress he had stripped away most of the fur on his tail, it was so sad to know that Huskies have a glorious bushy tail
and darwin had this thin ratty thing.
Within a year it was back to where it should be.
It's most likely as Sid suggests just a Hot spot and Kodi has stripped it away because it's sore or irritable.
However it could be a stress reaction like Darwin.