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Monday, November 21, 2016

Are There Differences Between "Prescription" And Over-The-Counter Foods? (Part 1)

Recently I received a great question from a reader:
One of our cats was recently put on a novel-protein diet for IBD, in addition to prednisolone.  He's been responding well to the steroids, and we just put him on the new diet today.
The diet prescribed was Royal Canin PV, which is Venison and Pea, and goes for the lovely sum of $67/8lb bag.
I see that Natural Balance also has a Limited Ingredient Diet Venison and Pea dry formula, and the ingredient list is awful similar.  Is there any significant difference between the two, other than the Natural Balance being $40 cheaper?
Many food companies have realized that the "prescription" veterinary diets are a huge revenue opportunity.  Therefore some of them are trying to develop OTC foods that are supposedly comparable to the veterinary ones as a way to capture a share of that market.  While I understand this from a business perspective and don't fault them for wanting to increase their corporate revenues, it does cause confusion among pet owners and difficulty for vets.  But the OTC foods are not always comparable to the veterinary ones. 
Royal Canin, Hills, Purina, and Eukanuba all make veterinary-specific diets for use in treating various medical conditions.  Inflammatory bowel disease (IBD) is a common one that needs a change in food, as it is often related to a sensitivity to ingredients (typically proteins, but secondarily carbohydrates).  Because these ingredients are not brand-specific we look at changing to "novel" foods, which means foods containing ingredients to which the pet has not previously been exposed.  In the above case the protein comes from venison and the carbohydrates from peas.  For a truly novel food you want to avoid other major ingredients, especially the protein.  In order for a diet to qualify as "limited ingredient" you want single sources of proteins and also ideally carbohydrates.
I compared the ingredients of both the Royal Canin PV and the Natural Balance LID Venison and Pea.  Both of them pass the "limited ingredient" test, as both rely only on venison for protein and pea as the major carbohydrate.  But there are some slight differences in minor ingredients, though none that I can see will make a huge difference in the nutrition of the diet.  One thing that Royal Canin has is some added fish oil.  The omega fatty acids in fish oils are a natural anti-inflammatory so they can be a great additive to cases like this.
On the surface it looks like these two foods are nearly identical.  However, there is another consideration that is not obvious, and there is no way tell from the packaging.....quality control.

With veterinary-specific diets the manufacturers spend a lot of time and money to ensure that other trace ingredients don't get into the mixture.  OTC diets may not have those same quality controls.  Ingredients must be listed by pre-cooked weight, but when you get to trace ingredients you may not have them listed because they are below a certain threshold.  What this means is that if there are minute amount of ingredients not listed on the label, that is allowable.  The more expensive diets are very careful to keep these trace ingredients out of the diet, while OTC diets typically don't care about them and may include them.
Why is this an important distinction?  Think about someone with a severe peanut allergy.  These people can't eat anything that has even touched nuts, whether or not it is an ingredient.  A food prepared on a counter that had previously had nuts on it could trigger an allergy.  Some people are so sensitive that even the nut dust being in the air is enough to cause a reaction.  While not common, some pets are similarly sensitive to even trace ingredients that wouldn't be on the label.

When these questions come up with my own clients I typically recommend feeding only the veterinary diet until the pet is stable for several months.  Once we have achieved effective control we may discuss trying a comparable OTC diet and watching for a reaction.  If there is no reaction we can use the less expensive diet.  If there is a return of symptoms we have to go back to the veterinary one. 
Remember that when using these very specialized foods you are not just providing nutrition.  These are being used as medical therapy.  You need to look at these foods in the same way that you would consider pills, capsules, and other medications.
Before making any food switches be sure to consult with your veterinarian first.  If you make the switch and the dog or cat isn't any better, the vet may assume that the prescription diet is failing when it's really the OTC one.  Since the diet recommendation is a vital part of the treatment, you need to keep your vet in the loop on any decisions.
This is a great topic and brings up some other issues that I'll discuss in some upcoming blogs.