Nutritional management of allergic skin disease: a roundtable discussion (Sponsored by Royal Canin)
Dr. Liska: The patient may have GI signs at the time of presentation, or if I look back in their medical history they have been a patient with GI disturbances such as intermittent gastroenteritis or perhaps chronic vomiting.
Dr. Fadok: In our practice, I'd say 25-30 percent have GI symptoms, but not major ones. Otherwise Internal Medicine would be seeing them.
Dr. Felsted: Does it help you diagnostically knowing about GI symptoms?Dr. Garfield: I always felt like the history or presence of concurrent GI symptoms made me suspect food allergy a little bit sooner. From my experience, probably one-third would be high. Certainly with chronic GI disease, the presence of soft stools or multiple bowel movements a day, five bowel movements a day, may be more of an indicator of food allergy than vomiting or diarrhea.
Dr. Felsted: What do you think is the most effective way to diagnose adverse food reactions?
Dr. Garfield: I believe the only way to diagnose food allergy is with a restricted food trial. We often have patients referred to our practice that have been ELISA or RAST tested previously. I do not think I have ever seen a negative ELISA test for food antigens. I also have probably never seen one that I could rely on the results to be of diagnostic significance.
Dr. Strauss: Yes, I would say multiple studies have demonstrated that the ELISA antibody titer type test for food allergens is not diagnostic. My recommendation at this point is not to even run those tests. They are just not helpful.
Dr. Felsted: Dr. Liska, has your experience been different?
Dr. Liska: No. I still absolutely believe the best way to diagnose a food hypersensitivity is by changing to a novel protein diet or a hydrolyzed diet.
Dr. Felsted: What food options are available for dietary trials?
Dr. Liska: I spend time looking at the diet history and then use that diet history to determine what I think is the best novel protein or the best hydrolyzed diet for that patient.
Dr. Fadok: My preference is to start with a novel protein. But if the animal has already gone through a diet trial, or if there's a palatability issue, I will switch to a hydrolyzed soy diet.
Dr. Garfield: Unfortunately, it is not uncommon that by the time these patients see a specialist, they have already been exposed to multiple novel proteins. That makes it harder for us to choose a restricted or novel protein diet that is appropriate for that patient. In these instances a hydrolyzed protein diet may be useful.
Dr. Strauss: I would just categorize the diet choices as novel protein diets and hydrolyzed diets. I think there is also the home cooked option which a lot of dermatologists rely on fairly heavily. I do not use home cooked diets all that much just because compliance is an issue. I also worry about long term nutritional status of those patients.
Dr. Felsted: All of you have mentioned using novel protein diets as a way of diagnosing adverse food reactions. Are there any disadvantages?
Dr. Liska: I do try to acknowledge to my client that the restrictions we are instituting will make the next three months challenging.
Dr. Felsted: Does it usually take that long? Dr. Liska: Yes.
Dr. Garfield: I would say two months is the minimum. These patients often have secondary otitis, secondary staph folliculitis, malassezia dermatitis, all kinds of stuff going on. So it is fine to start the diet trial but you also need to treat these secondary infections, often for 4-6 weeks, to get them resolved. Then you take away the supportive therapy and see if they are able to maintain on the hypoallergenic diet alone. In some cases it can take three or four months in tough cases to get all that secondary stuff cleared up before you can take the training wheels off and see how they do with just the hypoallergenic diet.