Inflammatory Bowel Disease (Chronic Enteropathies) in Dogs

Key Takeaways

Inflammatory bowel disease (IBD) is a term used for a group of inflammatory gastrointestinal diseases that are the result of disturbed interactions between the immune system, microbiotica of the intestine, and environmental inputs.

• Symptoms include chronic vomiting, diarrhea, eventual weight loss, gas, loud digestive sounds, straining to defecate, blood or mucus in the feces, and urgency to defecate

• Diagnosis is presumptive: if all other causes have been ruled out, the diagnosis is IBD

• Most cases of IBD are food-responsive and recover with a change in diet to hydrolyzed or novel protein sources

• Some cases are antibiotic-, immunosuppressant- or steroid-responsive and recover with drug therapy

• Other cases are nonresponsive, such as those involving  protein-losing enteropathy. The prognosis in these cases is poor

A Closer Look: What is IBD in Dogs?

IBD is complex. Variation in severity reflects the many possible types of diseases involved, the structures compromised by the disease, and the level of inflammation. 

Dogs that vomit or experience diarrhea more than once a week for three or more consecutive weeks require the prompt attention of a veterinarian to determine underlying causes.

Depending on the type of hypersensitivity the dog experiences, different forms of IBD occur. Certain hypersensitivities lead to eosinophilic gastroenteritis, some to granulomatous enteritis, some to protein-losing enteropathy.

Risk Factors

IBD is most commonly associated with middle- aged or older dogs, although rare cases occur in younger dogs. Certain breeds have a higher risk of IBD. 

Possible associated conditions include:

• Gastric dilation • Volvulus • Thickened intestines • Malnutrition

Gastric dilation and volvulus are medical emergencies. Dogs with pale gums, vomiting, a swollen abdomen, or who suddenly collapse require emergency veterinary care.

Possible Causes

Research into the cause of IBD is ongoing. Factors theorized to be involved include: 

• Defects in the Gastrointestinal Lymphoid Tissue (GALT) • Allergens in the diet • Parasites or infections

• Permeability defects in the intestinal lining • Inadequate blood supply to the intestinal tract

• Biochemical or psychosomatic disorders • Adverse drug reactions

• Immune-mediated destruction targeting the intestine

Evidence currently supports the theory that the intestinal mucosa of dogs with IBD experience hypersensitive responses to allergens (benign proteins). These allergens stimulate an inflammatory response, which impairs the mucosal barrier, which in turn increases the intestine’s permeability to further allergens. Microbiome dysregulation and motility disorders are also theorized to play a role.

Main Symptoms

Symptoms are specific to upper and lower GI involvement. 

Symptoms of upper GI involvement include:

• Diarrhea - watery, normal to increased volume of feces • Chronic or cyclic/intermittent vomiting

• Changes in appetite • Weight loss in severe or prolonged cases • Dark, tarry stools • Gas

• Loud gastrointestinal sounds

Symptoms of lower GI involvement include:

• Diarrhea - more frequent bowel movements with smaller volume • Straining during defecation

• Blood in the feces • Mucus in the feces • Increased urgency to defecate

Testing and Diagnosis

Diagnosis of IBD in dogs requires the elimination of all other possible causes for the presenting symptoms. 

Diagnostic tools include:

• Physical exam • Blood work • Urinalysis • Fecal analysis • Bacterial overgrowth tests

• Diagnostic imaging, such as X-rays or ultrasound • Infectious disease testing

In severe cases, dogs are unable to withstand the significant time that treatment trials require. These cases are often diagnosed through biopsy of the intestinal wall, either through endoscopy, colonoscopy or surgery, to determine the underlying cause and treatment plan more quickly.

Steps to Recovery

Prior to all other treatments, anti-parasitics are applied to eliminate potential parasitic infections that may cause symptoms. 

Treatment begins once a presumptive diagnosis of IBD has been made. Treatment options are trialed sequentially, until symptoms resolve or improve.  

The first treatment is dietary therapy. Changes in diet resolve most cases of IBD. The regular diet is substituted with a hydrolyzed protein or novel protein diet. Hydrolyzed proteins are degraded to basic components that do not trigger an immune response. Novel proteins are proteins that the dog has not previously been exposed to, thus avoiding immune response. Novel protein sources include fish, rabbit, venison, or duck. 

Should dietary changes fail to have an effect, the next stage is the application of antibiotics. Antibiotic therapy leads to disruption of the microbiome of the GI tract, so antibiotics are only used for short-term treatment. Should antibiotic therapy fail to improve symptoms after 2 weeks, steroid therapy or immunosuppression is necessary.   Alongside these treatments, adjunct treatments help manage the complications or clinical signs of IBD. These include:

• Supplemental medications • Fiber • Probiotics

For dogs with diet-responsive forms of IBD, improvement is seen in a few days or weeks from the onset of the new diet. For dogs with antibiotic-responsive forms, improvement should be noted in 2 weeks. 

For dogs requiring steroids or immunosuppressant drugs, treatment takes as long as 8 weeks. 

Environmental factors, especially the capacity of the pet parent to undertake strict dietary changes, administer drugs and undertake other therapies determine the success of treatment plans. Relapse is common. In some cases, relapses become more and more intractable. In non-responsive cases or in cases where protein-losing enteropathy is involved, prognosis is poor.

Prevention

No measures have been found to prevent IBD.

Is IBD Common in Dogs?

IBD is a common cause of chronic vomiting and/or diarrhea.

Typical Treatment

• Dietary changes with hydrolyzed or novel protein • Soluble fiber • Probiotics • Antibiotic therapy

• Steroid or immunosuppressant therapy