The medical condition in which humans or animals eat non-food objects--like dirt, grass, toilet paper, stone and even faeces--is called “pica." Most dogs abandon such behaviour by the age of 2 years old.
Medical Causes in Dogs
Adult dogs sometimes consume paper because of serious medical conditions, including malnutrition, vitamin deficiency, stress, diabetes and gastrointestinal cancer.
There are less alarming psychological reasons why dogs eat tissue paper: boredom, which causes dogs to use their mouths to investigate unsuitable objects; a refusal to give up the puppy state, when teething was a common practice; and a craving for attention from their owners. Hostile attention is better, a dog reasons, than no attention.
Veterinarians warn of the damage to the gastrointestinal organs that eating paper might incur, with the resulting symptoms of vomiting, diarrhoea and prolonged lethargy.
Prevention and Treatment
Experts encourage a wide range of approaches to the problem: exercising the dog by taking it for at least two walks a day to induce healthy fatigue; replacing the tissue with a chew toy or bone too large to be swallowed or shredded; giving it an alternative task to perform as it approaches the tissue; and applying a muzzle.
If the habit persists, consult the vet to determine whether the causes are medical or psychological and about strategies for discouraging it.