While you may be familiar with irritable bowel syndrome (IBS) in humans, inflammatory bowel disease (IBD) in dogs is a whole other beast. Inflammatory bowel disease in dogs can be quite serious and requires a lot of management. Here, we’ll help you understand this condition, how it’s diagnosed, and treatment options.

What Is Inflammatory Bowel Disease in Dogs?

Inflammatory bowel disease in dogs is an intestinal disease that causes gastrointestinal signs (especially diarrhea), doesn’t have a known origin, and has lasted at least three weeks. With IBD, inflammatory cells are infiltrating the innermost lining of the intestines.

IBD in dogs can also be more specifically named based on what type of inflammatory cell is infiltrating the intestinal lining and what part of the intestinal tract is being infiltrated.

For example, if two types of white blood cells called lymphocytes and plasma cells are infiltrating the small intestine, we call this lymphocytic-plasmacytic enteritis. If a white blood cell type called a macrophage infiltrates the lining of the large intestine, we would call this granulomatous colitis. Other variations exist, but again, it depends on cell type and whether the small intestine and/or large intestine is infected.

The true prevalence of inflammatory bowel disease is not known. One study estimated the prevalence to be approximately 0.35 percent, or 35 out of 1,000 dogs (1).

Causes of IBD in Dogs

The exact cause of IBD is not known, but it’s thought to result from abnormal interactions between the microscopic organisms in the intestines and the dog’s own immune system, ultimately resulting in an uncontrolled immune response. Inflammation of the intestinal lining and subsequent poor absorption result in gastrointestinal signs.

Genetics likely play a role in the development of IBD in dogs, but information is limited. IBD can affect dogs of all ages, but older dogs are more likely to have severe forms.

Dog breeds that may be more likely to develop inflammatory bowel disease include (2):

• Weimaraners
• Rottweilers
• German Shepherd Dogs
• Border Collies
• Boxers

A specific form of IBD called granulomatous colitis more commonly affects Boxers and French Bulldogs.

In some dogs, infiltration of the intestines by inflammatory cells can be so severe that the absorption of proteins is impaired. In this case, it is called protein-losing enteropathy (PLE).

Breeds more likely to develop PLE include:

• Yorkshire Terriers
• Soft-Coated Wheaten Terriers
• Rottweilers
• Shar-Peis
• German Shepherds
• Norwegian Lundehunds
• Basenjis

Dog IBD Symptoms

Chronic diarrhea in dogs is one of the hallmark symptoms of IBD in dogs. While mild IBD may cause intermittent clinical signs, severe IBD will cause progressive clinical signs.

When the small intestine is affected by IBD, the dog will have what is called small bowel diarrhea. Because the small intestine is the location where most nutrient absorption occurs, the pet is more likely to have systemic signs like weight loss. Symptoms will include:

• Diarrhea which is often loose to watery, increased in volume, and occurs two to four times per day
• Decreased appetite
• Weight loss
• Vomiting
• Lethargy
• Poor haircoat
• Dehydration
• Pain or discomfort in abdomen
• Fluid build-up in abdomen, around lungs, and in limbs with PLE

When the large intestine is affected by IBD, the dog will have large bowel diarrhea. Dogs with large bowel diarrhea do not typically lose weight. Symptoms include:

• Diarrhea which is loose to semisolid, normal to decreased in volume, and occurs over four times per day
• Mucoid and/or bloody stool
• Occasionally vomiting
• Decreased appetite
• Abdominal pain

IBD can affect both the small and large intestine simultaneously (enterocolitis). In this scenario, the dog will have a mixed bowel diarrhea, meaning they will have signs of both small bowel and large bowel diarrheas.

Diagnosing Inflammatory Bowel Disease in Dogs

Diagnosis of inflammatory bowel disease involves ruling out other conditions.

Your veterinarian will likely want to perform fecal examinations to rule out parasites. Even if they do not find parasites, they may wish to treat with a broad-spectrum anthelmintic drug to remove any doubt that parasites could be contributing to the pet’s condition.

X-rays and ultrasound of the abdomen allow the veterinarian to look for abnormalities in the abdomen. Some veterinarians may be able to detect changes in the intestinal wall or enlarged lymph nodes that may increase the suspicion that the pet has inflammatory bowel disease.

The veterinarian will likely also perform blood work and urinalysis to look at the pet’s overall health. Hypoadrenocorticism (Addison’s disease) can cause chronic diarrhea and weight loss, so it’s a good idea for the veterinarian to rule out Addison’s disease. This is done with a blood test.

If no obvious cause is noted after these tests, the veterinarian may recommend a dietary trial using either a novel protein or hydrolyzed protein diet.

In most cases, dietary intolerances are related to the protein in the dog’s diet. A novel protein diet aims to provide a protein that your dog is less likely to have been exposed to before, such as rabbit, venison, or alligator. With hydrolyzed protein diets, the proteins are broken down into smaller nutrients that may be more tolerable.

Diet trials are usually continued for at least eight weeks. Importantly, you must control everything that enters your dog’s mouth. They should not have table scraps, treats, oral preventions or medications that contain flavoring (consult with a veterinarian before stopping any medications), or access to trash.

Definitive diagnosis would require biopsy of the intestines. This can be done endoscopically or through an abdominal surgery. A pathologist will look at the intestinal biopsies and can determine if inflammatory cells are infiltrating the intestines.

How to Treat IBD in Dogs

Treatment for IBD can range from a simple dietary change to long-term daily management.

Treatment includes:

• Deworming
• Novel protein or hydrolyzed protein diets, which are often successful as the only necessary treatment in mild cases
• Antibiotics
• Probiotics
• Supplemental vitamin B12 (dog can become deficient with chronic diarrhea)
• Fluid therapy
• Antinausea medications
• Steroids or immunosuppressants

In severe cases, immune suppression with steroids (prednisone) may be necessary. If steroid immunosuppression is still not working, you can consider other medications that affect the immune system, such as cyclosporine, azathioprine, or chlorambucil. You will want to work with your veterinarian to find the lowest effective dose.

If your pet also has PLE, they may need additional medications like clopidogrel or aspirin to reduce the risk of blood clots. These medications should not be given without consulting your veterinarian.

At-home treatments are unlikely to completely control your dog’s IBD. However, some pets may respond very well to a home-cooked diet. You should work with your veterinarian or a veterinary nutritionist to formulate a home-cooked diet that is well-balanced and eliminates food items that your dog may be reacting to.

Dogs with large bowel diarrhea may benefit from the addition of soluble fiber, like psyllium. If you are interested in giving psyllium, check with your veterinarian.

Dogs that respond well to an elimination diet are expected to do well long-term. Dogs with

low albumin (protein level), low B12 levels, and severe intestinal lesions noted on endoscopy or during surgery are unlikely to achieve full control of their symptoms. Dogs with IBD who develop protein-losing enteropathy typically have a more guarded prognosis, and their disease can be very difficult to manage. 

How to Prevent IBD in Dogs

IBD is not considered a preventable disease. However, regular monitoring of your pet’s bowel movements, appetite, and general behavior can help you catch chronic gastrointestinal conditions earlier for treatment.

References

1. Wiles, Bonnie & Llewellyn-Zaidi, Aimée & Evans, Katy & O’Neill, Dan & Lewis, Tom. (2017). Large-scale survey to estimate the prevalence of disorders for 192 Kennel Club registered breeds. Canine Genetics and Epidemiology. 4. 10.1186/s40575-017-0047-3. 
2. Kathrani A, Werling D, Allenspach K. Canine breeds at high risk of developing inflammatory bowel disease in the south-eastern UK. Vet Rec. 2011 Dec 10;169(24):635. doi: 10.1136/vr.d5380. Epub 2011 Sep 6. PMID: 21896567.