It is not uncommon for a dog to develop diarrhea, and most of the time, diarrhea is not a serious issue. However, diarrhea that is unusual or reoccurring should be brought to the attention of a veterinarian to rule out potentially serious health issues.
If possible, discern the cause of the diarrhea. Puppies and adult dogs are prone to getting into---and eating---items they shouldn't. Knowing what caused the diarrhea will help determine the best treatment.
A temporary change in diet can relieve gastrointestinal upset in a dog. Ideal choices include cooked meats paired with rice, cottage cheese or oatmeal.
Some types of over-the-counter human medication can be given to dogs to relieve diarrhea, such as Kaopectate or Pepto-Bismol. Always ask your veterinarian for the dosage that is safe for your dog's weight and breed.
Diarrhea can quickly lead to dehydration, so encourage your dog to drink plenty of fresh water.
It is important to contact a veterinarian if the diarrhea persists for more than a day. If there are additional symptoms, such as lethargy, bloating or fever, seek veterinary care immediately.
Chaparral Animal Health Center: Treating Acute Diarrhea And Chronic Diarrhea in Dogs
Dogs Fun Times Guide: Acceptable Household Medications for Pets
Dog Diarrhea.org: How to Treat Dog Diarrhea
Dog Diarrhea.org: Home Remedies for Dog Diarrhea
Pet MD: Diarrhea That Can Be Treated With Antibiotics in Dogs
Dog Breed Info: Diarrhea in Dogs and Puppies