/// QUARTERLY BEAT / OCTOBER 2021
QUARTERLY BEAT / OCTOBER 2021 ///
SPONSORED ARTICLE
Adverse Food Reaction: When Diet is the Problem—and the Solution
ALISON MANCHESTER , DVM, DACVIM (SAIM) Veterinary Specialist and One Health Fellow Colorado State University College of Veterinary Medicine
How often do we experience gastrointestinal (GI) upset and say to ourselves, “It must have been the burrito/ice cream/ sausage pizza/bean dip I ate.”? If we’re sensible, we avoid consuming the offending food until at least the next time our cravings overcome our common sense.
Unfortunately, dogs can’t perform this kind of self-regulation, even though their kibble may be the culprit behind their chronic diarrhea, vomiting, flatulence and/or poor appetite. As veterinarians, we often overlook diet as a potential instigator of GI distress and instead jump to the assumption that a patient with GI issues must be suffering from a parasitic or bacterial infection. As a GI-obsessed internist, it’s disappointing to walk into a consultation and learn a dog has been struggling with GI distress for months or years, undergoing treatment with metronidazole, tylosin, dewormers, and holistic supplements, with only a passing reference to dietary investigation. In many cases, a simpler, safer option might have been to first consider changing the dog’s diet. The term “adverse food reaction” is broad. It encompasses everything from a true food allergy to food toxicity to intolerances of proteins, fiber sources or fats underpinning a host of chronic enteropathies . The good news is that approximately two-thirds of dogs with adverse food reaction can experience marked clinical improvement, if not full clinical remission, when we feed them the right diet.1 ASK QUESTIONS—AND LISTEN We can’t ask our canine patients how they’re feeling, but we can get a lot of information from the owner. The catch is that owners don’t always know what’s normal and what’s not. Ask a client if their dog is experiencing “diarrhea”, and you may miss something simply because the client doesn’t realize that their dog’s bowel habits actually might indicate GI dysfunction. A thorough nutritional history is also vital. Unless you probe deeper, the client may tell you their dog is eating a prescription hydrolyzed diet, but neglect to mention that the dog also gets the milk at the end of the cereal bowl, three rawhide chews a day and “a bite” of whatever the owner eats for dinner.
RUN THE RIGHT TESTS After you take a diet history, the next step should be to ask yourself, “Is this animal sick or well?” If the dog has a good appetite and normal body condition, a conservative approach, such as switching the dog to a different over-the-counter food or to a therapeutic GI diet, may be appropriate. If the animal is not well, with a decreased body condition, loss of muscle mass and/or a poor appetite, a more thorough investigation is warranted. I start with a minimum database of a CBC, chemistry panel and urinalysis. These tests can help rule out renal or liver disease, leukogram abnormalities, nonregenerative anemia, and hypercalcemia. These results might alter your differential list and workup. While veterinarians may be tempted to confine testing to a GI panel because of cost concerns, evaluating B-vitamin levels and pancreatic enzymes will provide little information beyond ruling out conditions such as exocrine pancreatic insufficiency. The minimum database gives the clinician a much better overall assessment of the dog’s health. SEPARATE FOOD INTOLERANCE FROM FOOD ALLERGY Does this scenario sound familiar? The patient in your exam room is a two-year-old dog suffering from chronic small bowel diarrhea and nonseasonal pruritus with chronic otitis externa. Such signs could be due to an adverse food reaction or perhaps a true food allergy. An elimination diet trial is needed at this point to diagnose the condition. While the idea of a strict elimination diet may be daunting to some clients, the good news is that such a trial will not necessarily be a two-month ordeal. In fact, if the dog improves within a couple of weeks, a nonimmunologic food intolerance should be suspected versus a food allergy. Furthermore, many
ELEMENTAL DIETS—ARE THERE OTHER APPLICATIONS? Elemental diets have been used with great success in human patients with conditions such as pediatric Crohn’s disease. Not only can patients achieve clinical remission, but they experience mucosal healing as well—without the use of medications (e.g. oral glucocorticoids) that can cause serious side effects. Beyond their lack of immune stimulation, elemental diets are thought to benefit patients because the calories are readily assimilated and digested. This helps address the malnutrition component, that can be a significant component of people and dogs with chronic intestinal disease. The veterinary profession is still learning about potential applications for elemental diets, but the potential to help dogs with chronic enteropathies or to diagnose food-allergic dogs that react to novel protein and hydrolyzed elimination diets is exciting. Adverse food reactions are a common cause of GI upset in dogs. Thanks to the wide range of therapeutic GI diets—from hydrolyzed diets to low-fat, high-fiber and elemental diets, veterinarians have the means to help patients in ways that do no harm—but can do much good. REFERENCES 1. Allenspach K, et al. Long-term outcome in dogs with c hronic enteropathies: 203 cases. Vet Rec 2016;178:368. 2. Allenspach K, et al. Chronic Enteropathies in Dogs: Evaluation of Risk Factors for Negative Outcome. J Vet Intern Med 2007;21:700-708. 3. Walker D, Knuchel-Takano A, McCutchan A, et al. A Comprehensive Pathological Survey of Duodenal Biopsies from Dogs with Diet- Responsive Chronic Enteropathy. J Vet Intern Med 2013;27:862–874.
dogs with food intolerance vs. food allergy may eventually be able to resume eating their former diet.2 This supports the theory that nutritional therapy can allow the gut to heal.3 When clinical signs—including both GI and dermatological— recur with deviations from the prescribed diet (including attempts to transition back to the original diet), the presence of true food allergy becomes a lot more likely. In my practice, many owners are averse to rechallenging with a previous diet, and that is fair. One instance where I would not advocate for a deviation from a beneficial diet would be in protein- losing enteropathy dogs responding to an ultra-lowfat diet. That suggests the presence of lymphangiectasia, and fat restriction should be life-long. SELECT THE DIET FOR THE ELIMINATION DIET TRIAL For dogs with suspected food intolerance or allergy, a dedicated feeding trial with an elimination diet is a must. For most cases, a hydrolyzed diet that is highly digestible fits the bill. Hydrolyzed diets are formulated by taking a native protein such as soy or chicken and using enzymes or heat to break the proteins into tiny pieces that can go unrecognized by the immune system. However, a small number of patients will react to hydrolyzed proteins as well as intact proteins. A new dietary option for elimination diet trials is an elemental diet for dogs. An elemental diet sources individual amino acids and combines them with a carbohydrate and fat source to make a complete and balanced diet. Because the immune system cannot detect individual amino acids, this type of diet is effectively the gold standard for hypoallergenic diets.
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