tail curling

Question
i have a German Shepherd, 1 year old and her tail curls and touches her back.why do they curl their tail? and is that an impurity?

Answer
It is uncommon, but not unknown for a Shepherd to have what is called a ring tail.  I am not sure whether it is a behavioral thing or structural.  As far as a show dog, it would be a fault, making the dog non competitive.  As far as an impurity is concerned, there is disagreement on that point, with both sides having little to back their strong opinions.  You could do DNA selecting ones with ring tailed breeds such as the Husky or Malumute in their data base.  See http://www.biopetvetlab.com/dnahome.htm http://www.wisdompanel.com/  Again, the current DNA testing is suspect too.  

Your dog may or may not be a pure bred, and it will not place well in a show.  That doesn't mean it can't be a great dog.