A simple definition of diarrhea is too much water in the stool. There are several different reasons this affliction can occur including:

If too many food particles are present in the intestines, this prevents them from absorbing enough water. This occurs with over-eating, when rapid changes in the diet are made, and during stressful situations. When a dog eats too much, there may not be enough digestive enzymes produced to breakdown all of the food. When a rapid change in diet is made, digestive enzymes do not have time to adjust to the new type of food.

During stressful situations, the amount and type of digestive enzymes change. In all of these situations, more undigested food is left in the intestines. These extra food particles hold on to water and keep it from being absorbed by the intestines.

If a dog has an infection or has eaten food from the trash, excess water can be present in the intestines which results in diarrhea. This situation can also be caused by intestinal parasites, E. coli and Salmonella.

Most cases of abrupt onset of diarrhea in dogs are caused by rapid changes in diet, eating out of the trash can, stress and intestinal parasites. Some dogs also get diarrhea when they take antibiotics. In many of these cases, dogs do not get severely ill. If a dog does get severely ill with diarrhea and develops other symptoms, this is an indication that there may be a systemic illness causing the diarrhea. For these dogs, it is important that they see a veterinarian immediately.

Visiting the Veterinarian

For the most part, mild cases of diarrhea do not require a visit to the veterinarian as they usually resolve on their own. So, in mild cases, it is perfectly acceptable to wait to see a veterinarian for 24-36 hours after the first onset. However, if your dog is uncomfortable, has bloody or tar like stool or acts ill, it is imperative to seek the assistance of a veterinarian. Even if the diarrhea does not clear up right away, you have the peace of mind knowing that your dog has been examined for more serious afflictions.

After the veterinarian examines the patient, he or she will want a fresh stool sample. If your dog has recently (in the last 30-45 minutes) had a bowel movement, you can collect that and take it with you. If not, the veterinarian can collect a sample in the office. Several things will be done with the stool sample. These include:

A fecal flotation to check for intestinal parasites

The Fecal Smear Test - This method tests the stool for red and white blood cells as well as any abnormal bacteria.

Fecal Smears with abnormal bacteria that resembles tennis rackets.

If a dog has had diarrhea for several days, has bloody diarrhea, seems to be very ill, or has other symptoms such as vomiting, its a good idea to have blood work and x-rays done. Both of these tests are used to check for other systemic illnesses that might be causing diarrhea.