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Makes Your Pet Feel Rotten, If Only for a Fleeting Moment

Can set off a cascade of negative GI symptoms. The underlying cause may determine how long it lasts. Here's what to expect from your vet as you try to get to the root of this perplexing and potentially frustrating inflammatory disease.


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  • Colitis is inflammation of the colon. An irritated, inflamed colon disrupts the final stage of the digestive process
  • Colitis has a number of potential causes, and can either be acute, episodic, or chronic
  • Symptoms of all three forms of colitis include diarrhea, painful cramping, nausea and vomiting. Pets with chronic colitis typically have additional symptoms such as dehydration and weight loss
  • Treatment of colitis requires identifying and resolving the underlying condition(s) that are causing inflammation of the colon
  • I recommend partnering with an integrative veterinarian who is skilled in treating pets with colitis, dysbiosis, and other gastrointestinal disorders

Editor's Note: This article is a reprint. It was originally published July 03, 2016.

Colitis means “inflammation of the colon.” The colon is also called the large bowel or large intestine. It’s the last functional section of the gastrointestinal (GI) tract responsible for the final stages of digestion.

Colitis occurs when the lining of the colon becomes irritated and inflamed, disrupting the last part of the digestive process. It’s the result of inflammatory cytokines that accumulate in the colon and disrupt the normal cellular structure and junctions of colonic tissues.

Inflammation triggers secretions of mucus and other substances from the lining of the colon that interfere with normal gut motility. Inflammation of the colon triggers a cascade of gastrointestinal events on a cellular level and reduces the colon’s ability to absorb water from dietary waste products, and store and transport feces.

This causes the stool to become loose, watery, greasy and sometimes tinged with mucus or fresh red blood.

Pets with colitis can’t tell us how they’re feeling, but based on how humans with colitis feel, we can assume that a dog or cat with this condition is dealing with a substantial amount of discomfort and pain.

Causes of Colitis

Colitis is often caused by one of the disorders of inflammatory bowel disease (IBD), which includes lymphocytic-plasmacytic enterocolitis, eosinophilic enterocolitis, granulomatous enteritis, neutrophilic enterocolitis, histiocytic ulcerative colitis, and possibly others.

Infectious causes of colitis are also common, including salmonella, campylobacter, giardia, E. coli, histoplasma and/or clostridium, as well as internal parasites.

Colitis can also be the result of an injury caused by a foreign body, physical trauma, or by ingesting an abrasive item or substance. Sometimes dogs eat things they shouldn’t, which can cause inflammation along the entire GI tract.

Allergic conditions and immunosuppressive disorders can cause colitis, as can stress-related irritable bowel syndrome (IBS).

Other causes include antibiotics that upset the normal flora of the bowel, food sensitivities or intolerances, environmental stress, ingestion of toxins or foreign bodies, and bacterial overgrowth.

Two much less common causes include fungal infections, and a toxic blue-green algae related disease called Prototheca colitis.

Pets at Increased Risk for Colitis

Some Boxers are predisposed to histiocytic ulcerative colitis, which is associated with IBD. German Shepherds and purebred cats have a higher incidence of lymphocytic-plasmacytic enterocolitis and associated IBD.

Irritable bowel syndrome, which is a common cause of colitis in dogs, is frequently seen in nervous or high-strung pets. Pets that eat indiscriminately, as well as free-roaming outdoor animals are also at higher risk for colitis.

I see a substantial amount of colitis in pets fed diets that aren’t compatible with their physiology, including prescription diets supposedly designed to address GI issues.

Acute colitis is often seen in young cats with intestinal parasites or intestinal bacterial overgrowth. Chronic colitis is seen more often in middle-aged and older cats, and is often caused by IBD or cancer.

Colitis Can Occur in 1 of 3 Ways

Colitis can be acute, episodic, or chronic. Acute colitis is typically more common in dogs than cats, and tends to resolve on its own within a few days, which is why the underlying cause often goes undiagnosed.

The symptoms appear suddenly, and other than diarrhea, your pet may seem normal. Sometimes an animals will be fine one minute and in intense pain the next.

Acute colitis is often caused by stress, ingestion of toxins or foreign bodies, dietary indiscretion, a dietary change or food intolerance, internal parasites, drug administration, or bacterial overgrowth.

Episodic colitis is usually sporadic and the symptoms can be mild to severe. Episodes can last for a few weeks. Chronic colitis, on the other hand, can last for months or even years and usually worsens over time.

Symptoms of Colitis

Common symptoms of colitis in all its forms include:

  • Watery diarrhea that may contain fresh red blood and mucus
  • Passing gas, painful cramping and/or straining during defecation
  • Increased urgency in dogs to get outdoors to poop; in cats, urgency to reach the litterbox
  • Secondary inflammation, redness, and irritation of the tissues around the anus
  • Soft stools; slimy or greasy loose stools
  • Nausea and vomiting

In chronic colitis, there can also be dehydration, lack of appetite and weight loss. Often pets just don’t feel well, so they avoid people and other pets. They may sleep more than usual, or appear reserved or lethargic. They may have a poor hair coat and body condition because they aren’t absorbing nutrients from their diet. If the small intestine is also inflamed, there can be black tarry stools instead of or along with diarrhea with bright red blood and mucus.

Diagnosing Colitis

Your veterinarian will perform a physical exam including abdominal palpation (feeling the abdomen). Bloodwork, including a complete blood count (CBC) and serum biochemistry profile will be performed, as well as a urinalysis.

A stool sample will be examined for GI parasites. A stool sample should also be sent out to a laboratory for polymerase chain reaction (PCR) testing to check for the presence of campylobacter, clostridium, giardia, salmonella, corona, and parvovirus for dogs, and tritrichomonas and panleukopenia for cats.

Abdominal x-rays may reveal masses or tumors in the GI tract, fecal impaction, thickened large intestinal tissues or other abnormalities.

If symptomatic treatment doesn’t resolve the problem, the most useful procedure for identifying the underlying cause of colitis is a colonoscopy that can be used to remove tissue samples from different areas of the lining of the colon. The camera at the end of the scope allows your veterinarian to visualize the lining of the colon to check for areas that appear abnormal.

Treatment Options

Treatment of colitis requires identifying and resolving the underlying condition(s) that are causing inflammation of the colon. To deal with the symptoms of colitis in an otherwise healthy pet, a common approach is to fast your dog or cat for 24 hours. As long as you have a healthy, vibrant pet that just has sudden diarrhea, fasting for 24 hours is fine. You never withhold water, however, just food. Then you slowly reintroduce a bland diet.

I recommend a bland diet of canned pumpkin and cooked turkey rather than the traditional rice and ground beef diet that many veterinarians recommend. With the canned pumpkin/cooked turkey diet, there are fewer carbohydrates and less sugar for abnormal gut flora to use as a food source. It’s also species-appropriate for dogs and cats.

The bland diet should be followed by a low-residue novel protein diet, especially if food allergies or sensitivities are suspected. The best way to determine what not to feed a pet with a suspected food allergy is Dr. Jean Dodds’ NutriScan test, which uses a saliva sample to accurately determine which foods your pet could be sensitive to.

There are a number of homeopathics, herbs, nutraceuticals, and different probiotic strains I use regularly that are very helpful in reducing GI inflammation. Certain procedures such as a fecal transplant can also be extremely beneficial. Whether therapies are introduced before, during, or after dietary change depends on your pet’s specific issues. Changing too many things at once can make symptoms worse.

Professional guidance is often needed to walk pet parents through the process, especially if you have a cat or dog that is hypersensitive and no matter what you do it tends to make the diarrhea worse. Often in these cases, we need to investigate the possibility of leaky gut syndrome (dysbiosis).

Most chronic dysbiosis patients need professional help. They need a veterinarian or other healthcare professional who is skilled in treating each patient as an individual, taking into consideration the animal’s breed, age, gender, and lifestyle stressors.

In my opinion, an integrative veterinarian is your best bet for identifying and treating the root cause of dysbiosis. Holistic and integrative vets have experience using healing protocols for colitis and leaky gut that conventional vets simply aren’t aware of, because alternative therapies aren’t taught in veterinary school.

Resolving Pet Colitis Can Be Challenging, but Don’t Give Up!

Because integrative protocols are based on the type of colitis your pet has, it’s impossible for me to cover the myriad of treatment options available in this video.

But if your pet has GI symptoms that haven’t resolved with a traditional treatment given by your veterinarian, for example, a drug like Flagyl (metronidazole) or Lomotil, don’t despair. There are plenty of other options you probably haven’t tried that can be very successful.

Other environmental and lifestyle factors you should address with your integrative veterinarian are future vaccines, which I don’t recommend for patients with GI issues. In fact, I don’t recommend any unnecessary vaccines. Instead, your vet should run titer tests to measure your pet’s immunity.

Future use of other drugs including heartworm, flea, and tick preventives should also be evaluated. Any chemical that goes onto or into your pet’s body has the potential to contribute to unaddressed sources of inflammation.


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