Why do dogs always eat grass outside?

Dogs always eat grass outside. It may be that the dog lacks certain elements. When the dog's body lacks certain trace elements, the dog will suffer from pica. addiction. When the dog appears to eat grass, eat dirt and other behaviors, it is necessary to help the dog replenish nutrition in time. It is important to ensure that the nutrition of the dog's food is balanced, so that the dog can receive more comprehensive nutrition and avoid the lack of trace elements.