Colitis in Dogs & Cats – An Angry Large Intestine!

The intestinal tract is quite long. It starts at the mouth
and ends at the rectum. Near the end of the intestinal tract is the large
intestine, otherwise known as the colon. When the colon becomes inflamed, we use
the term colitis. Colitis is a relatively common problem in dogs and cats with
a variety of causes. This week I’m sharing information about colitis to
increase awareness of this health condition, so I hope you find the post
helpful. Happy reading!


Colitis – What is it?

Colitis is the medical term that means inflammation of the
colon. There are a variety of causes of colon inflammation, including:

  • Stress
  • Bacterial infection (i.e.: Escherichia coli, Clostridium spp., Salmonella spp.)
  • Parasitic infestations (i.e.: giardia, whipworms, cryptosporidium)
  • Fungal infections (i.e.: histoplasmosis)
  • Allergies
  • Trauma
  • Inflammatory bowel disease
  • Cancer

Colitis – What does it look like?

There is no age, sex, or breed predisposition. Colitis may be acute or chronic. Acute means sudden onset while the term chronic means clinical signs have been present for more than three weeks. The most common clinical sign is diarrhea. It’s important to recognize the characteristics of colitis diarrhea. It’s not glamorous to think about diarrhea, but appropriately describing it is very important. Classic large bowel diarrhea is:

  • Semi-formed to liquid consistency
  • Small volume
  • Increased frequency of defecation
  • Presence of mucus (looks like clear jelly)
  • Straining to defecate
  • Increased urgency to defecate
  • Fresh blood in the feces (sometimes described as having a raspberry jam appearance)

Vomiting is typically documented in less than one third of
patients, and weight loss is rare.

Straining to defecate is a common clinical feature of colitis

Colitis – How is it diagnosed?

Diagnosing colitis is relatively straightforward and is
based on characteristic features of a patient’s diarrhea. What can be more
challenging is figuring out the specific cause of the inflammation in the large
intestine. Veterinarians may recommend some logical blood, urine, fecal, and diagnostic
imaging tests for patients with chronic colitis. Tests may include:

  • Complete blood count to check red blood cells, white blood cells, and platelets
  • Biochemical profile to evaluate kidney and liver function, electrolytes, and certain gastrointestinal enzymes
  • Urinalysis to help evaluate kidney function
  • Fecal examinations to look for specific bacteria, viruses, and intestinal parasites
  • ACTH stimulation test to screen for hypoadrenocorticism (Addison’s disease)
  • Gastrointestinal profile to evaluate specific B vitamins and to screen for exocrine pancreatic insufficiency & pancreatitis
  • Fungal screening

For patients with chronic colitis and depending on the results of the tests listed above, biopsies of the colon may be needed for definitive diagnosis. As in humans, biopsies from the large intestine can be obtained via a minimally invasive procedure called a colonoscopy (see video below).

Pet parents may find it helpful to consult with a board-certified veterinary internal medicine specialist to develop a logical and cost-effective diagnostic plan.

Colitis – How is it treated?

The specific treatment needed for colitis depends on the
underlying cause of the inflammation in the large intestine. For this reason,
it’s imperative to make an accurate diagnosis. The vast majority of patients
with stress-induced colitis simply need stress reduction and a short course of
an anti-diarrheal medication (i.e.: metronidazole, tylosin). Patients with bacterial,
parasitic, and fungal Infections should be treated with the most appropriate antimicrobial
agent. Some veterinarians may recommend a temporary dietary modification for acute
colitis, but this type of intervention isn’t always needed. Diets supplemented
with a fermentable fiber source like psyllium and beet pulp may be helpful. The
vast majority of acute colitis patients see their clinical signs improve within
48-72 hours and experience resolution in 5-7 days.

Patients with chronic colitis due to immune-mediated disease
often benefit from medications that modulate how the immune system responds to
inflammation. Patients with colon cancer may need surgery and/or chemotherapy. Families
may wish to partner with a board-certified veterinary internal medicine
specialist to develop an effective treatment plan for their pet.

The take-away message about colitis in dogs & cats…

Colitis or inflammation of the colon is a relatively common
problem in dogs and cats. Stress is a frequent inciting factor, but there are a
variety of other possible causes of inflammation in the large intestine.
Effective treatment depends on an accurate diagnosis, and prognosis is based on
the underlying disease process.

To find a board-certified veterinary internal medicine specialist, please visit the American College of Veterinary Internal Medicine.

Wishing you wet-nosed kisses,