Chronic inflammatory enteropathy in dogs: symptoms and treatment

Overview

Diarrhoea lasting more than three weeks is typically considered chronic. Symptoms may be continuous or return after symptom-free periods. Duration alone does not establish whether intestinal inflammation or another disease is responsible. Symptoms depend on the location of inflammation within the digestive tract.

In food-responsive disease, symptoms lessen or resolve with suitable nutritional treatment. Some dogs also need immunosuppressive medication to control inflammation. Protein-losing enteropathy, or PLE, means protein is being lost through the intestine.

Chronic enteropathy is suspected when gastrointestinal symptoms persist for at least three weeks. Granulomatous colitis is a rare form of inflammatory enteropathy affecting the large intestine.

Causes

Genetics, immunity, intestinal microbes and the environment probably act together in disease development. The intestinal mucosal barrier may weaken as part of the disease. Some affected dogs have less diverse intestinal bacteria than normal. Altered microbial metabolism can reduce short-chain fatty acid production.

Symptoms may improve when the dietary protein source changes. However, a good dietary response does not establish food allergy, as changing digestibility can also help. No single common causative bacterium has been identified for CIE. In granulomatous colitis, particular E. coli bacteria invading the bowel wall can be associated with inflammation.

Some dogs have altered intestinal bile acid metabolism. Dilated intestinal lymphatic vessels can leak protein-rich lymph into the bowel.

Risk factors

Inflammatory enteropathy is most often diagnosed in middle-aged dogs. Dogs under two years old can also develop chronic enteropathy. One estimate placed average symptom onset at 6.3 years. In young dogs, inflammatory enteropathy may be particularly likely to be food-responsive.

Increased susceptibility has been identified in breeds including German Shepherd Dogs, Soft Coated Wheaten Terriers and Shar Peis. Granulomatous colitis is a rare inflammatory form occurring particularly in young Boxers and French Bulldogs. At two Swedish animal hospitals, 814 dogs met chronic enteropathy criteria between 2013 and 2018. This represented 1.1% of all dogs attending those hospitals during that period. Median age at first presentation was 3.8 years.

Typical symptoms

A dog may seem well between episodes and then develop symptoms again. Whether diarrhoea has a small- or large-bowel pattern can give an initial indication of the affected area.

• Recurrent diarrhoea.
• Intermittent vomiting.
• Reduced appetite.
• Weight loss, even when symptom severity varies from day to day.
• Mucus in faeces with large-bowel diarrhoea.
• More frequent defaecation with large-bowel disease.

A dog losing protein through the intestine may accumulate abdominal fluid. Protein loss can also cause swelling of subcutaneous tissues.

Large-bowel diarrhoea may also contain fresh blood. Small-bowel diarrhoea can involve more marked weight loss through impaired nutrient absorption.

Complications and consequences

Persistent intestinal disease can cause malnutrition, particularly with protein loss. Around two-thirds of protein-losing dogs have poor nutritional status and muscle loss at diagnosis. Blood albumin can fall as protein is lost through the intestine. Increased blood clotting tendency has been found in 63–100% of studied dogs with PLE.

Increased clotting tendency predisposes to blood clots. Intestinal bleeding can cause anaemia. Non-regenerative anaemia, in which red cell production does not increase adequately, has been found in 12–19% of dogs with CIE. With severe protein loss, abdominal fluid or swelling may be associated with a poorer outlook.

Blood calcium may fall in dogs with protein loss. In protein-losing dogs, severe wasting of back muscles was associated with a lower chance of symptom remission within six months of diagnosis.

Diagnosis at the vet

Excluding other diseases

The vet reviews symptom onset, diet and the effects of previous treatments. Diagnosis involves investigating whether another disease explains the symptoms. Weight, nutritional status and muscle mass are also assessed. Faecal testing looks for parasites that can cause similar symptoms, for example. Blood testing usually includes a blood count, organ function markers and electrolytes.

If albumin is low, urine testing helps establish whether protein is being lost through the kidneys. A TLI blood test investigates exocrine pancreatic insufficiency. Cortisol testing can investigate hypoadrenocorticism. Cobalamin measurement assesses vitamin B12 status. Low cobalamin may be associated with a poorer outlook. It has been found in 19–61% of dogs with CIE.

Pancreatic lipase testing can help distinguish pancreatitis from chronic intestinal disease symptoms. The vet may assess symptom severity with CIBDAI or CCECAI scores. Scoring helps compare the same dog's condition before and during treatment.

Ultrasound and biopsies

Abdominal ultrasound examines lymph nodes and other abdominal organs as well as the bowel. It is particularly warranted with weight loss of at least 5% or reduced blood albumin. Bowel wall thickening alone does not establish chronic mucosal inflammation. A mass-like abdominal lesion may require cell sampling to investigate lymphoma, for example.

A stable dog eating normally is first given a dietary trial. If symptoms do not improve after three appropriate trials, endoscopy and intestinal mucosal biopsies may be needed. Endoscopy may be considered earlier if poor appetite prevents a dietary trial. Biopsies can identify the inflammatory cells accumulated in the mucosa. Biopsy inflammation does not generally identify which diet will relieve symptoms.

Biopsies are needed even if the mucosa appears normal to the naked eye during endoscopy. A deeper surgical sample may be considered if a lesion is beyond the endoscope's reach.

Intestinal mucosal calprotectin is an inflammatory marker under investigation. In one study from northern Europe, 44 dogs with CIE had increased duodenal and colonic mucosal calprotectin compared with 18 healthy controls. Calprotectin measurement does not yet replace other clinical investigations.

Treatment

Dietary trials

Depending on symptoms, food may be highly digestible, hydrolysed, novel-protein or higher in fibre. During a trial, the agreed food is the sole diet for at least two weeks. Initial signs of response are often seen within 10–14 days. Intermittent symptoms may require longer monitoring to assess the effect. A stable dog may try three different diets, as needed, before other treatments begin.

The transition to a new food can be gradual over seven to ten days before the trial itself. A high-fibre diet may be considered for large-bowel diarrhoea.

A good dietary response has been found in 38–89% of studied dogs with CIE. In many dogs, symptoms can remain controlled with diet for more than three months. If symptoms resolve, an effective diet is usually continued for at least 12 weeks before considering a change. A low-fat diet may help protein loss associated with dilated intestinal lymphatics.

Medicines and other supportive treatment

If adequate nutritional treatment does not help, the vet may consider anti-inflammatory medication for confirmed intestinal inflammation. The most effective diet can continue alongside medication. Confirmed vitamin B12 deficiency can be treated with cobalamin supplementation. Typical inflammatory enteropathy is not routinely treated with antibiotics.

In ordinary CIE cases, any antibiotic benefit may be short-lived if symptoms return after stopping it. For biopsy-confirmed bacteria-associated granulomatous colitis, the antibiotic is selected according to susceptibility testing. Probiotic benefits vary, and they do not replace an individually selected diet.

Nausea or vomiting can be treated separately according to symptoms. Cobalamin can be rechecked once treatment of a confirmed deficiency has ended.

In follow-up of 60 dogs, initial response classified 27 dogs, or 45%, as food-responsive. After at least a year, 44 dogs, or 73%, belonged to the diet-controlled group. Response-based classification changed in 24 dogs, or 40%, during follow-up. Nineteen of those changing groups moved from immunosuppressant-responsive to food-responsive. Of the 27 dogs initially classified as food-responsive, 63% had previously had an unsuccessful dietary trial.

Prevention

Because several factors contribute, no single food choice can reliably prevent inflammatory enteropathy. Continuing a suitable diet once found helps keep symptoms controlled. A protein-losing dog may need the effective diet long-term to prevent relapse. Home-prepared food used long-term must contain all required nutrients.

In protein-losing dogs, departing from the diet carries a high risk of relapse. If several changes to home-prepared food are needed, a vet with nutritional expertise can help plan a complete diet.

Important for dog owners

Record treats and table scraps as well as meals to help assess the dietary trial. Monitor stool consistency, weight and appetite. Dietary response is usually assessed at least weekly. If symptoms return, record what your dog ate in the preceding days.

Early monitoring also assesses possible medication side effects every one to two weeks. A protein-losing dog's albumin is initially checked every one to two weeks.

If albumin has normalised and the dog remains stable, monitoring intervals can extend to two to three months.

Frequently asked questions

Is CIE the same as human IBD?

CIE and human inflammatory bowel disease can resemble one another, but canine disease is not the same as human IBD. A dog's symptoms may improve with diet alone. Treatment is chosen according to the individual disease, symptoms and findings.

Does a dietary response mean food allergy?

Diet can improve symptoms by changing digestibility, for example, even without food allergy. Food-responsive enteropathy is assessed by whether intestinal symptoms settle with new food. Results are easier to assess when the dog eats only the agreed diet.

Is endoscopy always needed?

In a stable dog eating normally, the first step is often a dietary trial after investigating other common causes. Endoscopy provides biopsies if symptoms do not improve despite appropriate trials. It may be needed earlier if the dog is not eating.

What if the first food does not help?

Failure of one dietary trial does not mean another food cannot help. The vet checks whether the dog ate anything outside the agreed diet. Later changes may involve protein source or fibre content according to symptoms.

What does low albumin mean?

Low albumin may reflect protein loss through the intestine. The vet also assesses kidney protein loss and reduced liver protein production. General condition and albumin are monitored more closely with confirmed intestinal protein loss.