Stories from My Diary-rrhea (part IV): Chronic Large Intestinal Diarrhea

by Dr. Laci, aka, Dr. Poop 

After your veterinarian has narrowed down the origin of the diarrhea to large intestine and if your pet is still suffering from diarrhea (continual or intermittent) for 3-4 weeks, it is definitely time to delve in with a more aggressive workup.

It is crucial to revisit the history and disease progression with your veterinarian. 

Perhaps something was missed.  Details that seem unimportant to you (or you don't even think of) often unveil the case.  For instance, knowing that the rescue dog you just adopted came from a part of the country where fungal infection are prevalent and providing this information to your vet may make all the difference in the world to you and your dog.

Dogs with chronic large bowel diarrhea usually appear healthy on physical exam.  

This is not always the case, of course.  If your dog shows signs of being clinically unwell in addition to the diarrhea, a minimum database of lab tests is important to gain more information about how your dog's health as a whole is doing.  This may point towards a systemic problem and give your vet the information needed to know how aggressively and quickly action should be taken.

After obvious and easier causes are ruled out, large intestinal diarrhea calls for more invasive diagnostics.  

These diagnostics include many that have already been discussed in the previous posts:  fecal cultures, rectal cytology, x-rays, abdominal ultrasound, and enemas with dye to outline the path of the colon.  After performing all these tests and hearing that your vet still has no answers is very frustrating, and probably getting rather expensive.  Hang in there.

A colonoscopy with biopsy is likely the least invasive of the next advanced diagnostics, and the most direct way to find out what is happening in the colon.  

Colonoscopy and biopsies could reveal a number of diagnoses:  fungal colitis, a mass (such as a malignant tumor or benign polyp), bacterial infections, and inflammatory bowel disease.

Inflammatory bowel disease often affects both the colon and the small intestine and has many different types and underlying causes.  They are classified based on the predominate cell type affected:  lymphocytic-plasmacytic, eosinophilic, neutrophilic, granulomatous or histiocytic and are each worthy of lengthy discussion.

Dietary hypersensitivity is all too often overlooked, and can result in signs of chronic colitis.  

Opposite of natural logic, dietary allergies are usually not associated with a recent diet change because hypersensitivities develop over time as a result of chronic exposure.  There currently is no wonderful simple test to find out if your dog has a dietary allergy; a strict exclusion diet for 6-8 weeks is required.  This can be a pre-made processed prescription diet or a home-cooked one.  This takes profound patience on the part of the pet owner while their pet is still experiencing diarrhea but is the only current way to rule out dietary allergy.

In summary, the cause of your pet's diarrhea is not the easiest thing for your veterinarian to diagnose, and certainly not the easy for a pet owner to continually have the patience required to find the reason, especially when it is a chronic problem requiring what feels like endless tests.  There is often an easy reason for your dog's diarrhea, be it intestinal parasites or eating human food to rich and fatty for your canine friend, but many causes are serious and fatal if left untreated, such as lymphoma of the GI tract.

In all cases, diarrhea is a symptom of a disease. Finding out the disease is the difficult part. 

The responsibility to pursue the cause of your pet's diarrhea, and clean it up, lies in your hands.  You are your pet's health care advocate. I encourage you to find a veterinarian that realizes this.

Chronic Large Intestinal Diarrhea Characteristics:

• Weight loss is rare
• Appetite is usually normal
• Vomiting occurs in a small percentage of patients
• Feces volume may be normal or even slightly smaller
• Normal to greatly increased frequency of defecation
• Increased urgency
• Straining
• Frank blood
• Mucous

Related articles:
A Tale of Many Tails—and What Came Out From Underneath Stories from My Diary-rrhea (part I)
Stories from My Diary-rrhea (part II): Acute Small Intestinal Diarrhea 
Stories from My Diary-rrhea (part III): Acute Large Intestinal Diarrhea (Acute Colitis)
Where There Is Smoke, There Is Fire: A Symptom Is Your Friend, Treat It With Respect!
The House Is On Fire! Bridget's Pancreatitis
Help! My Dog Is Purple!
It's Your Dog's Health

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Laci Schaible has always been an animal lover and wanted to be a veterinarian since the third grade. Eager to actualize her dreams, she left home and started college with a full scholarship at the age of 16. She graduated with honors at the age of 19, and then became one of the youngest U.S. trained veterinarians in history when she graduated with her D.V.M. at the age of 23 from Texas A&M University.

After practicing as an associate at an emergency / referral and general practice small animal hospital, she was anxious to lead and manage her own hospital, which she successfully did for years. Performing surgeries with her husband Jed (also a vet) is one of her favorite aspects of practice.

Together, after losing their beloved family dog Madison to terminal cancer, Laci and Jed realized the need for pet owners to have affordable unbiased guidance for their pet's health care beyond their veterinarian with office hours. 

Jed's entrepreneurial genes and Laci's creative passion motivated them to fill this need, and VetLIVE.com was born.  Check out their blog for a mix of pet health advice, funny stories from the vet perspective, and even cool video blogs from Dr. Jed!

You can also follow Dr. Laci on Twitter  or VetLive on Twitter  or Facebook.