Eating things that are not food is a disorder called Pica. The most common thing a dog suffering from Pica will eat is rocks but they might eat other things such as clothing, cardboard or plastic. Obviously this can be very harmful to the dog.
There are generally two causes of pica in dogs. First is a lack of nutrition, either from eating poor quality food or from poor digestion due to an underlying medical condition. The second cause is a compulsive disorder often triggered by boredom.
If you think your good dog may be suffering from Pica you should have a thorough examination by your vet. A complete blood screening, a biochemical profile & urinalysis will be required. Abdominal x-rays should also be done to determine if there are any gastrointestinal abnormalities such as a tumor or foreign bodies that were ingested and stuck in the stomach or intestines.
If Pica is a compulsive disorder, proper training, more play time & plenty of exercise may be the key. A Knotty Toy would be ideal for playing tug or fetch.
Here are some links for further reading.
Dogster.com article on compulsive Pica
CEO Olivia ❤
Knotty Toys for Good Dogs 