The reasons why dogs always eat their own poop:

1. Fear of punishment. When training a dog to urinate at a designated location, in order to avoid punishment from its owner, the dog will take the initiative to eat feces and eliminate the evidence.

2. Negative psychological factors. When a dog is under great pressure and almost unable to bear it, it may develop pica and eat strange things to vent its negative emotions and gain satisfaction.

3. Poor gastrointestinal digestion. If a dog's gastrointestinal digestion and absorption is not good, a large amount of nutrients will remain in its feces and emit a "food" smell, which will make the dog think it can still be eaten.

4. Malnutrition. If a dog is malnourished, it can also cause pica, causing it to eat grass, poop, mud, sawdust, etc.

5. Too hungry. Dogs may eat their own poop when they are very hungry and cannot find food. After all, dogs are also scavengers.