Diarrhea in dogs does occurs sometimes as a result of food changes, foods that do not agree with, bacteria or internal parasites.
The biggest danger with diarrhea is dehydration which can lead to death, so can be very serious.
Often pet owners have no idea when or if they should seek vet attention.
so as a guide
any puppy 6 months or younger --seek vet advice immediately
any senior dogs,-- seek vet advice immediately
any dog with an existing medical condition-- seek vet advice immediately
any dog that has stopped or has decreased water comsumption --seek vet advice immediately
any signs of blood --seek vet advice immediately
if the dog is acting very quiet, tired or appears ill --seek vet advice immediately
in a healthy acting pup 6 months to a year that is drinking well , if it continues beyond 24 hours --seek vet advice immediately, phone calls to your vet are free, so ask for feeding caring advice to help you thru
in a healthy acting adult that is drinking well once it hits 3 days --seek vet advice immediately if it is the 1st or 2nd day on a thursday afternoon better to call the vet and get your dog in Friday or Saturday morning then chance having it lead into the weekend when your vet is not available again phone calls to your vet are free, so ask for feeding caring advice to help you thru
If the dog does clear up on its own or has repeated bouts get a stool sample and take to the vet for testing to rule out intestinal parasites or bacteria, If the dog is having repeated bouts than the dog should be seen by a vet to determine why, because that is not normal
"He is your friend, your partner, your defender, your dog. You are his life, his love, his leader. He will be yours, faithful and true, to the last beat of his heart. You owe it to him to be worthy of such devotion." - Unknown