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What is Clostridial Diarrhea?

The Clostridium perfringens bacteria are harmlessly present in a large percentage of dogs, many of which experience no symptoms. When the bacteria multiplies, it produces spores to help them withstand any environmental change, and enterotoxins, or toxic compounds. These toxins damage the cells in the intestines, and can result in diarrhea.

While the bacteria and the toxins they produce can remain harmless in low amounts, certain stressors can stimulate the bacteria to proliferate and produce high amounts of enterotoxins. Factors that can incite the bacteria to multiply can include stressful situations, like kenneling, or a diet change. 

Clostridial diarrhea refers to a condition of intermittent diarrhea that is caused or complicated by the presence of the Clostridium perfringens bacteria in the intestines. Believed to be the cause of around 30% of diarrhea seen in dogs, clostridial enterotoxicosis can affect dogs of any age, and can range from acute episodes lasting up to a week, to chronic, intermittent diarrhea that can continue for years.

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Symptoms of Clostridial Diarrhea in Dogs

While acute vomiting and diarrhea is an alert to the owner that something is wrong, there are cases of chronic diarrhea that is intermittent enough to cause little concern on the part of the owner, and could be mistaken for a food allergy or consumption of an indigestible item. Dogs can show no other symptoms and be quite bright and alert. However, Clostridial diarrhea can become serious, resulting in severe dehydration and shock, and should be treated if any diarrhea is present. Symptoms can be acute, occurring within a week’s time, or occur in intermittent episodes every 4 to 6 weeks, and can include:

  • Loose, semi-formed, or liquid stool
  • Bloody diarrhea 
  • Diarrhea with mucus
  • Small amounts of stool
  • Large amounts of watery stool
  • Urgency to defecate
  • Straining to defecate
  • Flatulence
  • Vomiting
  • Abdominal discomfort
  • Weight loss 
  • Failure to develop and grow normally


There are two distinct categories of diarrhea associated with the Clostridium perfringens bacteria.

Acute Diarrhea

Diarrhea that lasts for 5 to 7 days. Acute cases can cause hemorrhagic gastroenteritis, or a sudden case of bloody stomach and an inflamed intestinal tract that causes vomiting and bloody diarrhea. This is a serious life-threatening condition that needs immediate medical treatment.

Chronic Diarrhea

Diarrhea that is intermittent, occurring every 4 to 6 weeks over many months, or even years. This type is common in older dogs, and often goes undiagnosed.

Causes of Clostridial Diarrhea in Dogs

Clostridial diarrhea is directly caused by the enterotoxins produced by the Clostridium perfringens bacteria living in the intestines. 

Clostridium perfringens bacteria can be introduced to your dog through:

  • Consumption of contaminated food, in both vegetative and meat sources
  • Consumption of contaminated soils
  • Exposure to infected dogs

While the bacteria and the toxins it produces can be present in a dog without any diarrhea or other symptoms occurring, there are situations that can stimulate the bacteria to proliferate and produce toxic amounts of the enterotoxins. Factors that can cause the Clostridium perfringens bacteria to proliferate include:

  • Stressful situations, such as a hospital visit or a kennel stay
  • Diet change
  • Allergic reaction
  • Ingestion of food with high amounts of the bacteria 
  • Abnormally high intestinal pH, promoting bacteria proliferation
  • Medication
  • Presence of other disease
  • Infection of another organism 
  • Immune system dysfunction

Diagnosis of Clostridial Diarrhea in Dogs

There are many reasons why your dog may be experiencing diarrhea. Based on the information you give your vet, such as any symptoms you have seen, the history of the diarrhea, any diet changes, and any possible stressors that your dog may have recently experienced, as well as the results of testing, your veterinarian can begin to narrow down the reason for your dog’s digestive problem. 

Tests generally begin with bloodwork, which can eliminate serious causes such as liver or kidney failure, and can also show a decreased plasma concentration, indicative of hemorrhagic gastroenteritis. Chronic problems may need X-rays, ultrasounds, or an endoscopy to obtain an intestinal biopsy for examination.

More often, a case of Clostridial diarrhea can be diagnosed through a fecal sample, which can show the presence of the bacteria. Often, the sample will need to be sent to a lab to make a definitive diagnosis through the use of an enterotoxin analysis. A PCR test can determine if the particular strain of bacteria present in your dog is capable of producing the enterotoxin responsible for the diarrhea.

Treatment of Clostridial Diarrhea in Dogs

Most cases of mild Clostridial diarrhea are treated with oral antibiotics for 5 to 7 days. A resolution of symptoms is usually seen within a couple of days, but the medication protocol should be completed. Chronic cases respond to prolonged antibiotic treatment, and can benefit from the administration of tylosin powder, either in capsules or mixed into food. 

In severe cases of vomiting and diarrhea, such as with hemorrhagic gastroenteritis, your dog may be in danger of dehydration and shock, and will need immediate administration of fluid and electrolyte therapy. Some dogs may even need blood or plasma transfusions. An intravenous injection of an antibiotic can also be given.

Once your dog returns home, your veterinarian may recommend a change of diet. High fiber diets reduce the number of the bacteria in the intestines, and lower the pH, which lowers the ability of the bacteria to multiply, sporulate, and produce toxins. Psyllium or oat bran can produce favorable results. A prebiotic diet may help by changing the makeup of the intestinal tract, while probiotics can encourage healthy bacteria to take the place of the Clostridium perfringens bacteria. 

Transmission of the Clostridium perfringens bacteria can occur between animals, and even people, so be sure to monitor any pets and humans in the affected dog’s environment for signs of infection.

Recovery of Clostridial Diarrhea in Dogs

Recovery is good for dogs who receive treatment, whether it is short or long term. Your dog will also benefit from a high fiber diet, which can decrease the symptom of diarrhea and manage the bacteria. For severe cases, such as with hemorrhagic gastroenteritis, recovery can be good if treated in time. If left untreated, such a condition can be fatal. A follow up exam is often scheduled for 3 to 6 months after initial treatment to assess if the toxin is still present. 

If your dog has experienced Clostridial diarrhea, he may have a higher chance of another episode. An appropriate diet and a stress free lifestyle can prevent the bacteria from multiplying and causing problems in the future.