My dog eat feces when we were out walking

Hello together,

My dog always eats the dog poop from other dogs if I can recall him in time for dogs. While he is taking smaller pieces probably without chewing. Later everything must then back out and you can see the whole mess. Always again cyclically occurs the whole and not as permanent. And whenever it got better after a few days, then we have saved the trip to the doctor us. Do you have any advice?

LG Felix