Boredom or Frustration

• Dogs are social creatures that crave attention and affection from people and other animals. Dogs who are neglected can develop pica out of boredom or frustration from lack of attention. They commonly chew or ingest rocks out of boredom. Your dog is less likely to develop pica if you interact with him regularly and provide a loving, nurturing environment.
  
  

Curiosity

• Puppies are likely to eat rocks out of curiosity. They explore their new worlds by putting things in their mouths. Most puppies will stop this behavior when they realize that rocks are not a good source of food.
  
  

Nutrient Deficiency

• Some dogs, if not properly fed, can develop a nutrient deficiency. Nature's way of correcting a nutrient deficiency is to ingest the nutrients that are lacking, such as iron. Dogs commonly ingest rocks in an attempt to replace the vital nutrients that they are lacking. A blood test performed by a veterinarian will rule out nutrient deficiencies.
  
  

Disease

• Diseases such as brain infection, liver disease or lead poisoning can cause pica. When a dog's brain function is diminished due to disease, it will indiscriminately eat non-edible items. Veterinarians can test for these diseases through blood analysis and a physical examination.