A dog's stool that looks like ink may be caused by improper diet, indigestion, internal parasites, or gastrointestinal diseases. You need to observe whether the dog has other symptoms. If the dog is in poor spirits and has a loss of appetite, , vomiting and diarrhea, etc., it is best to take the dog to the pet hospital for examination immediately, and then carry out targeted treatment after confirming the cause to avoid delaying the condition.