Usually puppies are chewing will occurs prior to the age 16 weeks to 20 weeks of age.The older puppy needs hard objects to chew.Gnawing on bones or hard nylon chew toys helps relieve some of this discomfort. Also you can get regular physical exercise to your dog to waste energy on chewing and other unacceptable behaviours.Daily exercise of running,jogging or walking is healthy way for both you and your dog to avoid boredom.
參考: Better dog behavior correcting and curing bad habits books