The presence of diarrhea in dogs should always be a cause for concern. There are numerous causes of both acute and chronic diarrhea in dogs, including infectious agents, toxins, inflammation or disease of the intestinal tract, and parasites. Diarrhea can have a devastating effect on the body due to its dehydrating impact; left untreated, it can lead to blood sugar depletion, circulatory collapse, and death. While mild cases of diarrhea may resolve without intervention, diarrhea accompanied by vomiting, lethargy, or any other behavioral changes should be treated as a medical emergency. Because the severity of the underlying cause may not be immediately apparent, prompt medical attention is necessary to quickly diagnose and address the issue.
Diarrhea is always a symptom of an underlying problem and not a disease in itself. It can range from occasional loose stools to a continuous watery stream of feces. Unfortunately, many potential causes exist, and determining the cause may require collaboration between you and your veterinarian.
One of the most common causes of diarrhea is intestinal upset. A sudden change in diet, an unfamiliar treat, or feeding table scraps can trigger diarrhea. If the diarrhea is not severe and your dog continues to feel and act normally, it can often be resolved at home. Withholding food for 24 hours allows the dog’s digestive system to settle (while ensuring continued water intake). After 24 hours, you can offer small amounts of a bland diet, such as white rice and chicken. If the diarrhea subsides, you can gradually reintroduce their original diet and transition slowly to the new one. However, if diarrhea does not improve or worsens, veterinary treatment may be required.
To avoid intestinal upsets from dietary changes, all food transitions should occur over several days, allowing your dog to adjust to the new food. For the first three days, feed ¼ of the new diet and ¾ of the old food. If your dog is doing well, continue with half of each for another three days, then transition to ¼ old food and ¾ new food for an additional three days. This gradual approach helps minimize intestinal upset and reduces the risk of diarrhea.
Although many dogs receive table scraps, care must be taken to ensure that human foods are not too rich for their systems. Fatty foods can cause diarrhea and vomiting, and may also lead to pancreatitis, an inflammation of the pancreas that can result in chronic digestive issues. Additionally, while dogs enjoy many types of meat we consume, the form they are accustomed to (in their dog food) is highly processed. Giving large amounts of meat from human plates can be too rich and cause diarrhea. It’s also crucial to remember that dogs should NEVER be given turkey or chicken bones, as these can splinter and puncture the stomach and intestines.
Intestinal Parasites Can Cause Diarrhea in Dogs
Intestinal parasites are a common cause of diarrhea in dogs. Various types of parasites can infect dogs, and diarrhea is often one of the most frequent symptoms of such infections.
Roundworms are among the most commonly seen intestinal parasites in puppies. Although roundworms are not typically active in most adult dogs, puppies are particularly susceptible to their presence and effects. Dogs ingest roundworm eggs from contaminated soil, and puppies can receive them from their mothers. As the eggs hatch in the intestine, the larvae are carried to the lungs via the bloodstream. From the lungs, the worms crawl up the windpipe, causing gagging and coughing before returning to the intestine to mature. Roundworms can grow up to seven inches long and appear spaghetti-like—long and thin. Signs of infestation include a pot-bellied appearance, poor growth, and a rough, dull coat. Diarrhea and vomiting may also occur, and the dog may expel worms in their stool or vomit. If unchecked, these worms can lead to pneumonia, intestinal obstructions, and death.
Hookworms can affect dogs of all ages but are most common in warmer, humid climates. They are transmitted through the ingestion of contaminated feces. Mature hookworms attach to the intestinal lining and feed on the blood supply. In pregnant dogs, hookworms can migrate into the fetuses, infesting the puppies even before birth. Hookworms can be particularly devastating for puppies, leading to severe anemia, weakness, and bloody diarrhea.
While not a worm, Giardia is an intestinal parasite caused by a single-celled organism that resides in the intestines of infected animals. Recent research shows that Giardia is present in up to 11% of the general pet population and as many as 50% of puppies. It can be transmitted from pet to pet, through contaminated feed or water, and through soil. Pets who frequent dog parks, doggy daycare, or kennels are at a higher risk for infection. The most common symptom of Giardia is diarrhea of varying severity, although many infected animals may show no symptoms for extended periods, making routine testing vital.
Coccidia is another single-celled organism that infects the small intestine of dogs. Some dogs with coccidia show no signs of illness, while others may experience severe bouts of watery stools and bloody diarrhea, vomiting, depression, fever, and even death due to severe dehydration. These serious side effects are most common in puppies and adult dogs suffering from other illnesses.
Diarrhea in puppies is particularly concerning, as it is often the first symptom of severe and potentially fatal viral diseases such as parvovirus, coronavirus, and distemper.
Parvovirus is most commonly found in young, unvaccinated dogs or those who have not completed their vaccination series. The virus attacks and kills the cells in the intestinal lining, preventing the dog from absorbing nutrients and liquids. Dogs with parvo typically develop a high fever, lethargy, and loss of appetite. Profuse, liquid diarrhea occurs as intestinal damage progresses, and the stool may be foul-smelling or contain blood. This condition can lead to severe dehydration, shock, and death, often proving fatal even with aggressive treatment. Vaccination is the best prevention against parvo.
Like parvo, the coronavirus is a highly contagious virus that causes gastrointestinal issues. While adult dogs may experience mild symptoms and recover within days without treatment, puppies can develop far more serious infections and complications. Signs of coronavirus are similar to parvo, including profuse watery diarrhea, which, if left untreated, can cause severe dehydration and secondary complications.
Canine distemper virus is a devastating, highly contagious disease that primarily affects unvaccinated dogs and puppies. The virus typically targets the brain, intestinal tract, and upper respiratory system. A high fever is usually the first sign of infection, accompanied by coughing, sneezing, and green nasal discharge. As the virus progresses, it affects the intestinal tract, causing vomiting and dark, tarry diarrhea. Eventually, the virus can travel to the brain and spinal cord, leading to seizures and uncontrollable twitching.
There is no cure for distemper; medical treatment focuses on controlling symptoms and supporting the dog’s body during the infection. Even with aggressive treatment, distemper is often fatal, and survivors may suffer lifelong neurological issues. Vaccination is the best way to prevent distemper.
Other causes of acute diarrhea in dogs can include bacterial infections (such as salmonella and E. coli), toxin exposure (from insecticides and lead), and even stress.
Treatment for acute diarrhea in dogs focuses on diagnosing and correcting the underlying issue. If your dog has had loose stools for less than 24 hours but is otherwise acting normally (with a normal energy level and eating and drinking normally), you may choose a conservative approach and monitor their condition. However, if your dog shows any additional signs of distress or has had increasing amounts of diarrhea for any length of time, a visit to the veterinarian is required.
Your veterinarian will take a full history of your dog’s condition, including when the diarrhea first started and any possible precipitating factors. After a comprehensive physical exam, your veterinarian may recommend:
Fecal testing: A sample of the diarrhea will be obtained and checked for evidence of parasites such as roundworms and coccidia. An antigen test may also be performed on the fecal sample to check for Giardia.
Fecal cultures may be recommended to test for the presence of bacteria in the stool, such as salmonella.
Blood work: Blood chemistry tests assess various body systems and provide insights into the health of your dog’s major organs, such as the kidneys and liver. A complete blood count (CBC) evaluates the components of your dog’s blood, including red and white blood cells and platelets. The CBC can help diagnose or rule out infection as a potential cause of your dog’s diarrhea.
Parvo test: In puppies, a parvovirus antigen test may be performed. This quick “snap” test uses a small sample of feces, with results typically available within minutes. The sooner parvo is diagnosed and treated, the better the chance of a favorable outcome for your puppy.
X-rays: Radiographs of your dog’s abdomen may be recommended to rule out potential intestinal obstructions or foreign bodies that may have been ingested.
Treatment for your dog’s diarrhea will depend on what your vet suspects might be causing it. In cases of intestinal upset, a bland diet may be all that’s needed to settle
