Hi, We adopted a 9 mo. Old German Shepherd pup from animal welfare 4 months. Ago. In the house he bites almost constantly or chases his tail and barks loudly. What can we do?

How much exercise does he get every day?

I agree, he may just be understimulated... also, has he been treated for fleas/worms?

I would start with a vet check if you haven't discussed this with a vet. If he is eating very much else except a decent dog chow, he could have nutricianal inbalances leading to itching. A daily brushing could help that too as well as leaving less dog hair to sweep up.

As I think Emland is getting at, more expercise may be part of the answer. Just enriching his life with games of fetch or something could help. He is old enough you could take him to obedience lessons. Good leadership is very important. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at Raising Your Dog with the Monks of New Skete (http://www.dogsbestfriend.com/) For more on being top dog, see Establishing and Keeping Alpha Position, Letting your dog know you are the boss (http://www.dogbreedinfo.com./topdogrules.htm)