As one of the most frequent health issues experienced by dog owners, diarrhea can be caused by a number of things, and often is a secondary symptom of an underlying disease. Any diarrhea issues lasting more than a day or two should be brought to your vet’s attention, especially if other serious symptoms are present.
Although not a comprehensive list, the most commonly seen causes of diarrhea seen in dogs are:
Dietary Indiscretions and Changes
This is particularly common in puppies, where even slight diet changes will cause diarrhea. Even with adult dogs, it’s important to not make sudden diet changes or give too many treats, table scraps, etc as these can all contribute to digestive issues.
Intestinal Parasites
Dogs are prone to a number of different parasites, especially as puppies or adult dogs with compromised immune systems. If your dog is not on preventative treatment for hookworms, roundworms, whipworms, coccidia and giardia, it’s a good idea to collect a stool sample to bring to your vet. Checking for intestinal parasites is one of the first steps your vet will take in diagnosing the cause of diarrhea.
Intestinal Infections (Bacterial, Viral or Fungal)
Similar to parasites, dogs are also prone to a number of bacterial, viral and fungal infections such as clostridium, parvovirus, salmonella, distemper, etc. Keeping up to date with the required vaccinations will help prevent your dog from the most common viral infections.
Food Allergies
A major cause of digestive issues is a dog’s diet. Many dogs have sensitivities to the protein or meat source in their food, particularly chicken, beef and salmon.
Pancreatitis or Exocrine Pancreatic Insufficiency (EPI)
An issue affecting the small intestines, there are usually (but not always) other signs including weight loss and increased appetite.
Inflammatory Bowel Disease (IBD)
Often a secondary issue that’s caused by parasites, infection or allergies.
Toxins or Drugs
certain medications including antibiotics and non-steroidal anti-inflammatories (NSAIDs) can cause diarrhea.
Intestinal Obstruction or Foreign Body Ingestion
Your dog may have ingested something such as rocks, gravel, sticks, bones, dirt, pieces of toys, clothing or even hair from excessive licking / self-grooming that is caught in their intestinal tract. Both diarrhea and constipation can be a result of this.
Systemic Disease
Any disease within an organ system (such as the liver, kidney, adrenal glands or bladder) can be an underlying cause of diarrhea.
Intestinal Neoplasia/Cancer
Certain cancers affecting the digestive system or even outside the gastrointestinal tract can cause diarrhea. In most of these cases, diarrhea will be persistent and other accompanying signs like bloody or dark stool may also be present.
Stress or Anxiety
Just like humans, dogs have sensitive stomachs that can be affected by stressful environments, especially during or after car rides or other travel.