The Ultimate GUIDE TO Colitis in Dogs And Cats

Pet owners everywhere are aware of the dangers of colitis in dogs and cats, but many don’t know exactly what causes it or how to prevent it. In this article, we will provide a comprehensive guide to colitis in dogs and cats, including its causes and symptoms, as well as the best ways to treat it. We will also discuss the potential risks associated with colitis, and offer advice on how to spot the condition early on and take preventative measures. So whether you have a pet dog or cat, read on to learn everything you need to know about this dangerous condition.

The term colitis in dog and cat is very general.  It often refers to any one of a variety of afflictions of the intestinal tract with emphasis on the large intestine (large bowel).  Whenever veterinarians are confronted with a case of colitis in the dog or cat, a process of elimination is started in order to achieve a specific diagnosis for what type of colitis is present. In general, colitis is either acute (sudden onset) or chronic (long term and reoccurring).  Below are a few abbreviations that are frequently used when referring to types of colitis…]



(In veterinary medicine, “signs” means the same thing as the word “symptoms” in human medicine.) The usual signs of colitis in  dogs and cats can cover a range of abnormalities from intermittent constipation to long term (chronic) diarrhea.  In general, because the bowel tissues are inflamed and irritated, the most common signs are frequent need to defecate and soft to watery stool.  Some dogs and cats with colitis pass liquid stool, often with blood, six to ten times a day.  Straining to defecate (called tenismus) while producing little or no stool, is another common sign.  These dogs and cats with colitis are very uncomfortable and often their appetite is suppressed due to a general state of ill health.  Along with the debilitating effects of passing frequent, loose stool (called diarrhea), many dogs and cats with colitis ( IBD, IBS, SBS ) will display a gradual weight loss.  Chronic colitis almost always creates a weight loss situation in dogs and cats due to the loss of vitamins, rapid transit of food through the entire gastrointestinal system, blood and fluid loss, and infectious agents entering the animal’s body through the damaged intestinal wall. 

DUTIES OF THE COLON  The words “colon”, “large intestine” and “large bowel” are interchangeable.  This portion of the digestive tract is the last segment to retain the digested food that has been processed by the stomach and small intestine.  (The small intestine has a smaller diameter but a four-times greater length than the large intestine). Very little goes on in the colon other than reabsorption of water, thus making the fecal volume smaller, bacterial breakdown of ingesta and production of certain vitamins.  Storage of the feces occurs in the large bowel until an appropriate time and place for elimination is selected.  All these functions, though, are seriously affected when a dog or cat develops colitis.

Common Causes of Colitis:

1. Parasitic – Whipworms reside in the upper colon (unlike hooks and rounds); protozoan parasites in some areas of the country are caused by Giardia, Trichomona, Amoeba and Balantida.
2. Foreign Body Colitis – We’ve all seen the dog that eats grass and straw.  This indigestible fiber really irritates the large bowel.  Any dog with pica (the compulsion to eat non food material) is a candidate for intermittent colitis.
3. Bacterial Colitis – Often is caused by Salmonella and Campylobacter.
4. Chronic Inflammatory Bowel Disease ( IBD )- This is an important group.  This disorder is due to an invasion of the wall of the large bowel by certain types of body cells.  Eosinophilic Colitis is a good example. Another common cellular infiltration into the wall of the large bowel is due to lymphocytes and plasmacytes. This is referred to by veterinarians as LPIBD… Lymphocytic-plasmacytic Inflammatory Bowel Disease and is thought to be due in great measure to allergic reactions within the bowel and even throughout the digestive tract.  The wall of the large intestine is invaded by the individual’s own inflammatory cells in response to some triggering antigen.  An allergen is any substance that incites an immune reaction.
5. Irritable Bowel Syndrome – Usually has a neurological or psychological origin.  It is seen often in the hyper-excitable dog that is stressed, overworked, or apprehensive.
6. Typhilitis – Inflammation of the cecum which is a dead-end pocket branching from the intestinal tract where the small and large intestine join.  (The medical term for this area is Ileoceco-colic junction.) This is located near where the human appendix would be, however  dogs and cats don’t have an appendix.
7. Cancer – The two most common types are lymphosarcoma and adenocarcinoma.  

The following email question was sent to a veterinarian regarding “colitis” and how to treat it.  The veterinarian’s answer displays how difficult it is to formulate a single, precise answer to this topic of colitis…


 The most obvious signal of colitis is loose stool, mucus and an increased frequency of passage.  The dog or cat often strains to pass small amounts of stool and may actually appear to be constipated.
Note: Weight loss is not a common finding unless long term (chronic) colitis is present.  Rapid weight loss associated with loose stool usually means the small intestine is involved.  Red blood, rather than black, tarry blood associated with small intestine bleeding, is indicative of the bleeding coming from the colon.

The loose stool in colon disorders is due to lack of proper reabsorption of water from the feces.  This can be due to:
1. A hyperactive colon where the feces don’t spend enough time in the colon to have the water reabsorbed.
2. Interruption of the proper chemical reactions necessary for reabsorption of the water.

Diagnosis of colitis in dogs and cats:

1. History – It is very important to observe and describe accurately all  factors such as the type and frequency of stool, the dog’s environment, diet, stress factors, straining, etc.
2. Laboratory analysis – fecal exams are invaluable as a basic part of the patient analysis to determine the presence of parasites, undigested nutrients, and blood. A blood test for evidence of Pancreatic digestive enzyme insufficiency called an TLI Test (trypsin-like immunoreactivity) can be used to evaluate the ability of the pancreas to properly digest food presented to the digestive tract.  There are state-of-the-art blood tests that only a few laboratories can run that will indicate probabilities of specific food ingredients to which the patient may be hyper-responsive.
3. Radiography – Barium, a substance that shows up on an x-ray very well, can be given orally or via enema.  X-rays are very helpful in gathering data about the colon.
4. Colonoscopy – Direct visual exam by a specialist can be very revealing.
5. Biopsy – Often in chronic colitis the biopsy provides the final step in determining a diagnosis as to the cause.  This requires an anesthetic and surgical procedure, therefore, other modes of diagnosis and treatment are employed first. The biopsied specimens are sent to a veterinary pathology lab for what is called a histological exam by a specialist in veterinary pathology. 


The treatment depends of course upon the cause.  Whipworms in dogs must be ruled out  even if fecal samples are negative; so too with Giardia.  These single celled organism can be very debilitating to dogs and cats.  Antibiotics, proper worming, and adding bran to the diet are employed with varying success.  Food allergy is a multifaceted and difficult-to-manage disorder. There are  special ingredient foods (Therapeutic Diets) now available to help dogs and cats avoid the specific dietary ingredient that triggers the allergic response.  

As a general rule, the treatment of colitis is prescribed and applied according to what the final diagnosis is.  A thorough workup of each case is important because if a treatment protocol is undertaken and the actual cause is something other than the assumed cause, more harm than good can come of the “treatment”.  Often a specific  antibiotic will be prescribed that affects mostly intestinal bacteria and is not absorbed systemically like most antibiotics are when used to treat infections outside the intestinal tract.   Cortisone may be the drug of choice for chronic Inflammatory Bowel Disease but would be inappropriate for use in a Giardia infested dog or cat so the diagnosis must be accurate if success is to be achieved. 

Special diets, called Therapeutic Diets, may be prescribed by the veterinarian that contain select ingredients unlikely to irritate the bowel.  In many cases, chronic colitis will require lifelong therapy in order to achieve a good quality of life for the dog or cat.

By now, you must be able to tell that there is a lot of relation between colitis in dogs and cats.

In case you ever notice any signs of illness like loss of appetite, increased thirst, diarrhea or constipation in your dog or cat, it’s crucial that you take the animal to an expert vet as soon as possible. One wrong diagnosis can have fatal consequences for your furry companion. Also remember to keep a close eye on their diet and see if they have lost their appetite after some time.

Frequently Asked Questions

What brings on colitis in dogs?

Stress, infections (such as Salmonella, Clostridium, and E. coli), parasites (such as Giardia, Cryptosporidium, and whipworms), trauma, allergic colitis, and primary inflammatory bowel disease are some of the causes of colitis (lymphoplasmacytic, eosinophilic, granulomatous, and histiocytic types).

How does a vet diagnose colitis in dogs

Your veterinarian will need to do an examination to determine the presence of colitis. Bring a sample of your dog’s most recent stool so that it can be examined for parasites and worms. If necessary, your dog’s colon may be examined with an X-ray or a biopsy ordered by your veterinarian.

How do vets treat colitis in dogs?

Any bacterial infections or imbalances can be treated with antibiotics and probiotics taken at the same time. The veterinarian may adjust or stop the antibiotics if they believe they are to blame for the colitis. Immune stimulants and anti-inflammatory drugs can ease colitis brought on by IBD.

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