While diarrhea is a relatively common problem, what causes dog diarrhea is not always an easy question to answer. Diarrhea, or the frequent passage of soft, liquid stools can vary in severity in dogs from merely a nuisance, to a life-threatening emergency for your dog.
Diarrhea is not actually it’s own disease
, but rather a symptom of many other diseases and conditions. Gastroenteritis is the most common primary cause of diarrhea in dogs. Gastroenteritis is inflammation of the lining of the stomach and small intestine. The most common causes of gastroenteritis include:
- Viral infection
- Bacterial infections
- Adverse reaction to something ingested
Often, a mild case of gastroenteritis may be prompted by a dog eating something that they shouldn’t have. Table scraps, swallowing foreign objects, ingesting garbage, food allergies, eating something out in the yard or on a walk, and a myriad of other things that dogs get into can upset their stomach, causing diarrhea. After ingesting something that doesn’t agree with the their stomach, the body may trigger diarrhea to help void the unwanted material from the body quickly.
When there is a known event of doggy dietary indiscretion, one or two episodes of diarrhea are not necessarily cause for immediate concern. If despite the loose stools, the dog is still eating, drinking and feeling normally, and the problem quickly corrects itself, likely the body has cured the problem itself.
Continued episodes of diarrhea, coupled with blood or mucous in the stools, or signs of lethargy, poor appetite, or vomiting can signal a more serious illness or medical condition is at hand, and must be treated by a veterinarian immediately. While the primary danger of repeated episodes of diarrhea is the associated dehydration that can develop, the underlying cause must be investigated so that it can be treated quickly.
In puppies, what causes dog diarrhea are generally several more severe illnesses, which can quickly become life threatening if left untreated.
Canine parvovirus gastroenteritis is a common and highly contagious disease. Puppies and unvaccinated dogs are most susceptible to this insidious disease. This virus attacks and damages the cells of the intestinal lining, leading to severe damage in the intestinal tract. As the lining of the intestines sloughs, profuse, liquid diarrhea begins to occur. The diarrhea may appear bloody or even black colored, with a foul odor. Fluid loss from the diarrhea and vomiting can quickly lead to severe dehydration, shock and death. It is usually fatal if untreated, and carries only a guarded prognosis even in dogs diagnosed and aggressively treated for the disease. Vaccination is the best prevention for development of Parvo.
There are several types of bacterial infections common to dogs that can cause diarrhea. These include Clostridium perfringens, Salmonella, and many others that damage the intestinal lining and destroy the natural, good bacteria that populate the gut and ensure proper intestinal operation. Bacterial infections may be present for a long time in a dog and never cause a problem, until stress or other mitigating factors causes an outbreak. Dogs may have diarrhea of vary severities, and blood may be present as well in the feces.
Parasites can be why your Dog has Diarrhea
Parasites are a frequent cause of diarrhea in dogs, especially puppies. Coccidiosis and Giardia are both single-celled protozoa that live and reproduce within the cells in the intestine. Both these parasites can live for long periods of time within the intestinal tract without causing signs, however they can still be passed from dog to dog, and even to humans in the case of Giardia. Their most common sign is diarrhea, with watery diarrhea is the most tell-tale sign of a serious infection. These tiny protozoa are not visible to the naked eye, making fecal screening the only method of diagnosis.
Other intestinal parasites that can cause diarrhea in dogs include hookworms and roundworms. Transmitted via the ingestion of contaminated feces, hookworms attach to the lining of the intestinal tract and live off of the blood supply there. In pregnant dogs infected with hookworms, the parasites migrate to the fetus and infest the puppies before they are born. Hookworms in puppies can be very serious, as they cause severe blood loss, weakness and diarrhea. Hookworms can only be diagnosed via fecal screening.
By contrast, Roundworms are large, spaghetti-like parasites that can grow up to seven inches long, and are easily visible in a dogs stool. Their presence is almost always limited to puppies, where they grow quickly and cause a pot-bellied appearance, poor growth rate and coat condition, as well as diarrhea and vomiting. Because the worms mature in the lungs and windpipe, severely affected animals may cough or develop pneumonia.
What causes dog diarrhea is not always able to be determined. However, in any case of diarrhea regardless of cause, the primary concern is to stop the diarrhea and fix any dehydration and electrolyte imbalance that may have been the cause.
A veterinarian should see any case of diarrhea that isn’t resolved quickly at home. A physical examination will first be performed, where your veterinarian may recommend testing to assess your dogs physical condition, as well as try to determine the cause of the diarrhea.
Fecal testing in the form of a fecal floatation may be recommended to check for parasites. A fecal cytology may be recommended to check for the presence of bacteria. Antigen tests may be performed to detect the presence of Giardia. A positive result in any of these tests may be the definitive cause of the diarrhea, however treatment for the diarrhea must still be initiated to prevent further health deterioration.
In puppies, your veterinarian may first recommend a parvovirus antigen test be run. A positive result on this test signals an active parvo infection, and aggressive treatment must be started immediately for the best chance of saving the dogs life.
Depending on your dogs physical condition, blood tests may be run to determine the full extent of the problem, ensure his vital organs are functioning correctly, and to check for electrolyte imbalances. In most cases of gastroenteritis, IV or sub-cutaneous fluids may be administered to correct dehydration, and if no obvious causes can be found, medication may be administered to help stop the diarrhea.
What causes dog diarrhea can be a difficult diagnosis to make. While many mild cases can be treated at home, it is imperative that any dog with repeated episodes of diarrhea or other signs of illness be seen by a veterinarian immediately to help diagnose, treat and correct the underlying problem.