Chronic Small Intestinal Diarrhea in Dogs: Stories from My Diary-rrhea

Chronic small intestinal diarrhea is diarrhea that lasts continuously or intermittently for 2-4 weeks and hasn’t responded to therapies. Some of the causes discussed under acute small intestinal diarrhea will slide into this category inevitably, if not diagnosed properly and treated.

Of all the four categories I am discussing, this one is the doozie.

The possibilities and different causes seem far more endless. However, I will do my best to make the chronic small intestinal diarrhea, well, end.

What does small intestinal diarrhea in dogs look like?

Small intestinal diarrhea results in a larger amount of poop passed with a mild increase in frequency. It does not result in straining during defecation,

Affected dogs will also commonly

• lose weight
• vomit
• have increased gas 

If there is blood in the stool, it will be darker or black, as it will be digested.

Figuring out the cause

History, physical exam, medications the dog is receiving, and previous GI surgeries are all important.

Systemic problems that can cause chronic small intestinal diarrhea in dogs include

• food intolerance or allergy
• liver disease,
• or even herniated spinal cord discs

As with all diarrhea, how healthy or ill the pet is, determines how aggressive initial tests need to be.

Weight loss often accompanies chronic small intestinal diarrhea.

If your dog suffers

• weight loss
• oily grayish feces (steatorrhea–feces with excess fat that really stink)
• ravenous appetite

it is necessary to learn why they are not getting the nutrition they need.

Diagnosing chronic small intestinal diarrhea

The potential underlying conditions break down into three categories:

• inappropriate digestion (maldigestion)
• protein-losing diseases (protein-losing enteropathy/PLE)
• inappropriate absorption without protein loss (malabsorptive disease). 

Your vet will perform diagnostic tests to rule these conditions in or out.

Exocrine pancreatic insufficiency (EPI)

Exocrine pancreatic insufficiency (EPI) is the most common cause of maldigestion in dogs.

It can affect any dog, but we see it most often in young German shepherds. Many of these conditions call for a biopsy to reach an accurate diagnosis. This may involve endoscopy or exploratory surgery.

Protein-losing enteropathy (PLE)

PLE is a syndrome, not a singular disease, and has several causes: 

• obstructions
• toxins
• inflammation
• infections
• IBD (discussed under chronic large bowel diarrhea)
• lymphangiectasia (abnormal dilation of lymph vessels causing the loss of proteins and nutrients)
• and cancer

With PLE, a protein called albumin may be lost in diarrhea.

Albumin normally helps keep water in the blood vessels of your dog, similar to a sponge. With albumin loss in the stool, water starts to leak out of the blood vessels and into other places that gravity takes it such as

• legs
• the underside of the abdomen and chest cavity

With high enough protein loss, the dog may develop edema (fluid accumulation) of the legs or belly–as if they weren’t uncomfortable enough being hungry constantly and having chronic diarrhea.

Two huge causes of malabsorptive diseases are small intestinal bacterial overgrowth syndrome and dietary intolerance.

Unlike the large intestine which is rich with bacteria, the small intestine has significantly less bacterial organisms. Bacteria overgrowth in the small intestine alters digestion and leads to malabsorption and diarrhea.

A definitive diagnosis requires a biopsy, but oftentimes trial therapy with antibiotic therapy is effective.  There are advantages and disadvantages to both approaches. You will need to decide which approach you want to choose with the help of your veterinarian.  I will discuss dietary intolerance in a future post.

Back to the big picture, chronic small intestinal diarrhea is often very difficult to diagnose.

Although simple tests often suffice, there are times when invasive diagnostics may be necessary.  In veterinary medicine, this usually means heavy sedation, if not full anesthesia, which understandably frightens many pet owners.

It is important to remember though that chronic diarrhea is not normal or healthy.

Small intestinal diarrhea means your pet is continuously losing nutrition. Imagine living in a state of continual ravenous hunger; if your pet suffers from small intestinal chronic diarrhea and is wasting away, this is what they are living with!  Try to imagine this and hopefully you will pursue the cause and solution more seriously.

Over time, chronic small intestinal diarrhea can have dangerous consequences, even if the cause of diarrhea itself is not deadly.

If your dog is unfortunate enough to suffer from chronic small intestinal diarrhea, it may end up being one of those times you wish you had pet insurance. And tile floors.

Related articles:
Symptoms to Watch for In Your Dog: Diarrhea
A Tale of Many Tails—and What Came Out From Underneath 
Acute Small Intestinal Diarrhea
Acute Large Intestinal Diarrhea (Acute Colitis)
Chronic Large Intestinal Diarrhea
Chronic Small Intestinal Diarrhea

Further reading:
Diarrhea (Long-term) in Dogs