Colitis In Dogs: Symptoms, Causes, And Treatments

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Canine colitis is an inflammation of the colon in dogs. It’s responsible for some 50 percent of cases of chronic diarrhea in dogs, and while it doesn’t demand a trip to the emergency room, it certainly requires the input of your veterinarian.

The condition can lead to painful, frequent trips to the backyard for your dog, often to pass watery, bloody stool. And, like many conditions that frustrate an easy diagnosis, colitis can also have the opposite effect and cause constipation.

Here’s everything you should know about the colon and colitis in dogs.

What And Where Is The Colon?

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The colon is another name for the large or lower intestine. As food travels through the dog’s body, most of it is absorbed and used as fuel or stored as fat. The remaining food, composed mainly of indigestible fibers, enters the colon.

There are three functions of the colon: storing stool, absorbing water, and further digestion of unabsorbed nutrients. The colon’s bacteria count is approximately ten times denser than the bacteria in the small intestine.

The bacteria take the left-over fibers and break them down into three bio-chemicals: acetate, propionate, and butyrate.

These nourish the cells of the colon — which have a life expectancy rate of one week — and control the pH balance so that the toxins that are excreted will not be reabsorbed, as well as producing gasses and pigments used in creating stools.

What Are Symptoms Of Colitis In Dogs?

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Since your dog can’t tell you what they’re feeling, you must rely on outward signs to gauge their health. A major obvious symptom of colitis is diarrhea, though it can also result in constipation.

To properly classify and treat colitis-related diarrhea, it must be determined whether the problem is in the small intestine — which is the more serious of the two — or in the large intestine.

The following characteristics are commonly found in diarrhea of the large intestine:

  • Straining during defecation and a sense of sudden urgency
  • Fresh blood found in the stool
  • Mucus in the stool
  • Stools that start normal and finish loose
  • Stool is often gooey or slimy as opposed to watery
  • Passing gas
  • Dehydration from loss of fluids

While your veterinarian can diagnose colitis based on symptoms, treatment depends on the nature of the diarrhea. Is it acute (i.e., has it appeared suddenly), chronic (ongoing for several weeks), or episodic (recurring time after time)?

Sudden (Acute) Colitis In Dogs

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If your dog suddenly develops colitis, it may be induced by stress from events such as boarding, moving, severe weather, or some other change in lifestyle, or it could be from a dietary indiscretion, such as eating from the garbage can, consuming too many treats, or having a sudden change in diet.

These cases can usually be cleared up with proper medication and diet therapy. The veterinarian should also check for parasites, as they can cause colitis.

Chronic Or Episodic Colitis In Dogs

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If your dog’s colitis symptoms persist for over a month, your veterinarian will run tests to discover the cause. The tests will include evaluating your dog’s blood chemistry, a red and white cell profile (called a CBC), and a fecal test for parasites.

They may also need to test the pancreas for its ability to produce digestive enzymes. A veterinarian should perform a fecal smear or cytology test under the microscope to check for pathogenic bacteria that can cause colitis, especially the Clostridial organisms.

Whipworms are a common cause of colitis in dogs, but they are difficult to detect. If your veterinarian suspects whipworms, they may suggest treatment for the whipworm and see if that resolves the problem.

Other parasites in different parts of the digestive tract can usually be treated readily with medicine, but whipworms can be difficult to eradicate, and a multistep deworming process is usually necessary.

If the problems return after treatment, your veterinarian may recommend a colonoscopy with a biopsy in order to reach a diagnosis.

Other Causes Of Colitis In Dogs

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There are many possible causes of colitis in dogs, and it’s important that your veterinarian run tests to determine how to proceed with treatment and how to deal with underlying factors that may worsen the condition.

Here are a few other possible causes of canine colitis:

  • Chronic Inflammatory Bowel Disease: This is a group of diseases of the small and large intestines in which the dog’s immune system, reacting to an allergen or infection, attacks the lining of the intestine. Although treatable, it’s seldom curable.
  • Foreign bodies: Grass and straw contains lots of indigestible fiber that can irritate the colon. Dogs who eat any nonfood material are always at risk of suffering from periodic bouts of colitis.
  • Irritable Bowel Syndrome: Most commonly found in stressed or highly excitable dogs, this condition often has a neurological or psychological cause.
  • Allergies or dietary intolerance: Food allergies can especially cause inflammation in the digestive tract that leads to symptoms of colitis. Intolerance to certain types of food such as wheat or lactose can also cause inflammation.
  • Infection: Viral or bacterial infection usually causes an immune system response which results in inflammation.
  • Bowel cancer: This is especially the case with older dogs.
  • Reaction to medication: Some antibiotics can interact poorly with your dog’s digestive system and kill off good bacteria that aids the digestion process, resulting in upset.

Preventing, Managing, And Treating Colitis In Dogs

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You can’t prevent every cause of colitis — sometimes it’s just out of your control. You can, however, be sure your dog gets a high-fiber diet and plenty of water.

Also, try to keep them from eating any nonfood materials. Grass, fabric, and table-scrap bones all are very hard on the digestive system and can trigger problems.

The best way to manage colitis is to get an accurate diagnosis and use the specific therapy designed for that condition. If this is not possible, your veterinarian may try to treat the symptoms as they arise to control the problem.

Listed below are medications and strategies that can be useful in the management and treatment of your dog’s colitis.


This is an anti-inflammatory medication helpful in the large intestine, and it’s able to kill harmful organisms such as Clostridia and Giardia.


This medication is a sulfa antibiotic surrounding a salicylate anti-inflammatory. The sulfa bond keeps the anti-inflammatory medication intact through the stomach until it reaches the large intestine.

While it is an effective medication, some pet parents have trouble medicating their dogs three times a day, which is necessary.

Dietary Fiber

There are three types of fiber: soluble, insoluble, and mixtures. In general, vets believe colitis is a fiber-responsive disease. The fibers are broken down into food for beneficial colon bacteria and to provide nutrients for colon cells.

Fructooligosaccharides (FOS)

Some dog food manufacturers make a prescription diet that emphasizes the addition of FOS to its formulation. FOSs are carbohydrates connected with fructose (fruit sugar) units that attach to glucose (starch sugar) units.

While the bacteria of the small intestine digest most carbohydrates, FOSs, while not fibers, break down the same way in the large intestine and yield the same bio-chemicals as fibers. Tests have shown that this substance helps remove pathogenic (disease causing) bacteria from the large intestine and promote the growth of good bacteria.

Diets containing FOSs may help control colitis.

Elimination Diet

Colitis can result from food intolerance, either to a specific food or to preservatives, dyes, fillers, contaminants, or even the natural proteins in the food. Your dog could also have an allergy to a certain food, such as wheat or corn.

The best way to pinpoint these allergies is by feeding a pure diet, one that contains no food product in your dog’s current diet. You can make your own home cooked food or you can buy one of the many allergy specific diets available today, such as duck, rabbit, or sweet potato to name a few.

During the eight to ten week test period, the dog can only eat the special food, with no treats or goodies allowed. This is an easy way to determine a food allergy in your dog, and less expensive than the standard skin testing.

Treating Clostridium

Clostridial organisms are a group of anaerobic bacteria, meaning they cannot survive in the presence of oxygen. They’re responsible for such diseases as tetanus, botulism, and gangrene.

While some Clostridial organisms normally live in the large intestine, they don’t cause problems unless the dog becomes stressed or has a diet change that allows them to overgrow. Once they have grown to a large number, the high level of toxins they produce can cause colitis.

Diagnosis of Clostridial disease is complicated since a fecal smear may show its presence, but it’s not certain that the organisms are producing toxins.

Your vet may suggest additional tests, such as the reverse passive latex antigen testor the ELISA test, although some vets dispute the accuracy of these tests.

Sometimes a course of a Clostridium-killing antibiotic, such as amoxicillin, tylosin, clindamycin, and metronidazole, which has other properties to battle colitis, will be administered as a test.


This is still the leading weapon in the treatment of inflammatory bowel disease, which must be diagnosed by biopsy. Your vet will sometimes suggest a trial course of prednisone to treat the colitis.

Has your dog ever suffered from colitis? How did you treat it? Let us know in the comments below!