Diarrhea has no specific cause. It can be acute or chronic. It can be caused by diseases in the digestive system (primary gastrointestinal disorders), dog-toilet1or outside the digestive system ( extra-gastrointestinal disorders). Diarrhea can be caused by dietary intolerance, certain medication, parasites, bacterial, fungal or viral enteritis, foreign object in the digestive system,  liver disease, hyperthyroidism, pancreatitis, kidney disease, exocrine pancreatic insufficiency or even heart disease (right side heart failure) etc. Hence, a check up will be necessary to find out the underlying issues that caused the diarrhea. Depending on the other clinical signs your pet is showing, medical history (vaccines, deworming), and the result of the physical examination, further workup may be advised. In-depth testing such as a blood test, urine analysis, X-Ray or ultrasound might be needed to find out the primary disorders. Treatments are usually focused on the primary disorders that caused diarrhea and other signs such as dehydration, electrolyte imbalance, and low albumin, etc.  Antibiotics may be needed to control thrgrowth of bacteria and the imbalance of bacterial flora in the digestive system. Antidiarrheals are usually not needed because we wouldn’t want to hold the overgrown and imbalanced bacteria and the toxins they make in digestive system before we get the primary disorder addressed. That will result in more issues.  When you pet has diarrhea, they should be fed with a bland diet in small portions with increased feeding frequency. Talk with your vet for more details based on the case.