Why persistence pays off when it comes to dietary management of chronic enteropathy patients

If a patient is vomiting, has diarrhea, or is showing other gastrointestinal (GI) clinical signs, dietary management should automatically be on the table, says Dr. Adam Rudinsky, associate professor in the Department of Veterinary Clinical Sciences at The Ohio State University College of Veterinary Medicine.

He runs a laboratory dedicated to researching chronic enteropathies, pancreatic and hepatic disease, and intestinal microbiome. Dr. Rudinsky will be the first to acknowledge that getting owners to switch diets can be difficult.

"A diet switch is like a personal affront to people," Dr. Rudinsky said. "A lot of their self worth, in terms of that animal, is tied up in the diet that they feed them. So, it can be a challenging discussion, particularly when you have a busy schedule."

But he maintains it’s still worth the time and effort. He and Dr. Harry Cridge, associate professor of small animal internal medicine at Michigan State University College of Veterinary Medicine, each gave presentations on nutrition at the 2025 American Animal Hospital Association CON, held September 11-13 in Chicago. Both are board-certified specialists in small animal internal medicine.

Dietary selection

When considering a dietary management strategy, after taking a diet history, Dr. Rudinsky recommends asking these questions:

• What is the duration of clinical signs—acute or chronic?
• Where are the clinical signs localized? Stomach? Small or large bowel?
• Are the clinical signs consistent with a specific disease process, such as pancreatitis or parvovirus?

If the diagnosis warrants, a diet trial can be the first step, even before a biopsy or other invasive diagnostic procedure. Why? "Because many patients will respond to it and it’s cost effective," Dr. Cridge said.

Dr. Rudinsky outlined five main diet categories for dogs and cats with acute or chronic GI clinical signs:

• Highly digestible or low-residue diets: These diets take the work off the GI tract by requiring less digestive effort. Dr. Rudinsky uses these diets for dogs and cats that are underweight due to vomiting, mild small intestine disease, or acute GI disease because of their nutritional density.
• Novel or limited-ingredient diets: Often associated with use in chronic GI disorders, especially small or large bowel disease, these diets can also help with food allergies. However, Dr. Rudinsky says the prevalence of food intolerance appears to be much higher than the true food allergy, as most animals are responding to the antigen load. "If you continue to feed a diet that is too rich or varied, you can get those responses frequently that appear as a chronic condition," he said. When selecting a limited-ingredient diet, he advises choosing one with only a single carbohydrate and a single protein source in the ingredient list, both of which are ideally novel to the patient.
• Hydrolyzed diets: These diets undergo hydrolysis processing to reduce allergenicity and antigenicity by altering macronutrient structure. Typically, they are highly digestible and have a reduced fiber content. Often these are a mainstay for chronic GI symptoms, such as pancreatitis in cats and small bowel disease in dogs and cats. Specifically, Dr. Rudinsky said, "The more I have a vomiter … or a small bowel diarrhea case, I love a hydrolyzed diet."
• Low-fat diets: These are diets with fat content generally in the range of less than 3 grams of fat per 100 kilocalories. More recently, fat content has been identified as an important component in the management of some canine GI diseases, especially pancreatitis, GI motility issues, or mixed bowel diarrhea cases, Dr. Rudinsky said. This doesn’t appear to be an issue for cats. However, "for dogs, if you use an easily digestible diet, you might as well use one that is low fat too," he added.
• Fiber-enriched diets: Fiber is added to diets for multiple reasons, but especially diarrhea and large bowel disease in both dogs and cats. The fiber type and source will influence the type of effect that is seen in the patient. The benefits of soluble and insoluble fiber, besides helping with diarrhea (soluble) or constipation (insoluble) include fermentation, production of volatile fatty acids, benefits to enterocyte health, augmentation of the microbiota, as well as alterations in gut motility and passage of GI luminal contents.

When first getting started, Dr. Rudinsky recommends looking at hydrolyzed, novel protein, or easily digestible diets for cats. "Cats maintain the same response rate with easy digestible diets that they do with hydrolyzed and novel ingredient diets, but dogs do not," he said, so only start with hydrolyzed or novel ingredient diets for dogs.

Also important to note is that even among a particular diet category, options can vary by ingredient list, fiber content, fat content, and more. For example, Dr. Cridge says elimination diets differ in more than just their protein. He recommends using product guides for up-to-date nutrient compositions, including looking at dietary fat and fiber content.

Both Drs. Rudinsky and Cridge suggest looking at the global nutrient profile of diets when evaluating macronutrient diet choices. Do not focus on percent as fed, which doesn’t take into account water content and other features of the diet, but rather look at grams per 100 kcal, Dr. Rudinsky said.

This information may not always be on the bag. In that case, they recommend using Tuft University Cummings School of Veterinary Medicine’s Clinical Nutrition Service Nutrient Calculator or product guides to help with comparing nutrients between diets.

Dedication pays

Recent research reaffirms the importance of purposeful nutritional management, especially for patients with chronic enteropathies.

A retrospective paper published this past May in the Journal of Veterinary Internal Medicine (JVIM) looked at 81 dogs with chronic enteropathy. Among those in which the only therapeutic change was a hydrolyzed or other alternative diet, 88% (14 of 16) had a decreased stool‐consistency score and 70% (16 of 23) saw a 69% reduction in their total Canine Inflammatory Bowel Disease Activity Index score.

Another study, published in the September-October 2024 issue of JVIM, followed 60 dogs with chronic inflammatory enteropathy for two years. The initial dietary response rate was about 45%, but over time, 73% of them ended up being diet responsive and able to come off modulators.

"Giving more evidence that even if you don’t get that initial dietary response, diet is still a fundamental component, because your ability to minimize medications later on is going to be super useful," Dr. Rudinsky said.

Finally, he emphasized the importance of taking a complete diet history. A study out of the University of Zurich, published in 2022 in the journal Animals, found that dietary information gained from referring veterinarians and owners was often incomplete.

Among these dogs presenting to the university’s GI and internal medicine service, no dog had received more than one previous diet trial for chronic GI signs.

After prescribing all of the dogs a new diet, 58% had an initial dietary response. Then the researchers convinced all the owners with a dog that didn’t respond to switch to yet another diet, and those dogs saw a 66% dietary response rate. The researchers did this again and had a 44% dietary response rate for owners that had switched a third time.

"If you add those percentages up … they were able to drive their response rate up in chronic enteropathy animals up to 85% or 86%. So that is really powerful, especially if you think of those dogs that we’ve managed sometimes with super bad prednisone effects or other issues with chronic medications (to correct that)."

"A lot of us intuitively know this, but we’re so thankful if an owner even does one diet switch," Dr. Rudinsky said. "Don’t be afraid to ask them to switch again if first switch isn’t working."

So, when to switch? Dr. Rudinsky says, "If you have not seen a response in two weeks, you can abandon ship and switch. If you see a partial response at that two-week mark, then you want to go out to about four weeks."

Dr. Cridge says two weeks for him, too, and then he’ll move onto another diet for canine patients. "I don’t push owners to try a diet for too long because that’s when they want to give up and try something else," he said. For cats, he acknowledges the challenge is getting them to try the diet in the first place.

Another issue Dr. Rudinsky has noticed, beyond not convincing an owner to do a diet trial, is getting them to accept the cost of the new diet because many of them may be more expensive than what they are currently feeding their pet.

Finally, Dr. Cridge recommended referring patients to a board-certified veterinary nutritionist when there is a refractory case of chronic enteropathy or protein-losing enteropathy (PLE), presence of concurrent diseases, picky dogs that may need a home-cooked diet, or when owners wish to make a home-cooked diet.

"Nutritionists are invaluable resources, especially for refractory chronic enteropathy and PLE dogs and often will provide remote consultations directly," he said.