Dog food allergies are probably one of the most talked about topics in dog-parent circles. And in the veterinary clinic I don’t know how many times I have heard about pups that have had allergies to certain ingredients, or certain foods. “My dog is allergic to…. -insert food item here-” is a common conversation topic. However often these allergies are assumed and not actually accurate.
The truth is – if you actually speak with veterinary dermatology & nutrition specialists – food allergies ARE NOT that common at all.
“It is believed that only 14-33% of itchy pets actually have food allergies.”
Meaning that – most likely if you have an itchy pup – it’s not food allergies.
So just because your pup has signs pointing in the direction of food allergies, it does not mean that they actually have a food allergy or intolerance. Dermatological conditions can be complex, and pets presenting with “itching” can have many other conditions than food allergies. Some of which are: environmental allergies, external parasites, Hypothyroidism, Cushings disease or they could just be on an unbalanced diet.
Also Food Intolerances and Food Allergies are actually much different.
What is a food allergy in dogs?
When a dog has a true food allergy basically what happens is the body reacts to the food item as if it were an “invading force” like an infection/illness rather than a food. The immune system starts to respond – creating a cascade of inflammation – which can present clinically with many different signs.
A dog food intolerance by contrast has to do more with how the food item is digested within the body, and does not have an immune system associated response.
Why do food allergies happen?
The honest answer to this is that we largely don’t know exactly WHY they happen. But it is assumed that food allergies happen because of a combination of a genetic predisposition, exposure tot he allergen, and an environmental trigger.
You can think of it as a dog can almost be a carrier to the gene that causes food allergies, however it takes multiple different things happening within the dog’s life to cause the allergy to occur. It also takes multiple exposures to the allergen in question. This means your dog can literally eat beef for 10 years, AND THEN develop an allergy to beef.
“Dogs can have their first food allergy anywhere from 2 months to 14 yrs of age. However most dogs will have their first reaction around 1-2 yrs old.”
Are certain breeds predisposed to food allergies?
Irish Setters are actually one of the only breeds known to have Gluten Intolerance. At this time we do not know of which breeds are predisposed to food allergies. However depending on the source some breeds MAY be implicated…
- West Highland Terrier
- English Bulldog
- German Shepherds
- Labrador Retrievers
- Rhodesian Ridgebacks
- Shar pei
However – since there is a genetic component to food allergies, asking what your breeder feeds and WHY might be a good idea. I know of many breeders of Labrador who swear their dogs just do BETTER on fish-based diets. Now they don’t know if the dogs have allergies or an intolerance, but regardless it’s nice to know and keep it in the back of your mind just in case.
What are the Most Common Dog Food Allergens?
The important thing to remember when it comes to dog food allergies is that dogs can be allergic to any item that contains proteins within it, and the more proteins within an item the more likely they are to cause a reaction. So though the foods listed below are the most common dog food allergens, you should also keep in mind that they are also the most commonly fed – meaning that this list MAY be biased due to mere popularity of these items being fed.
Can you prevent dog food allergies?
There is no known way to prevent dog food allergies.
MYTH: feeding a novel protein diet like kangaroo, venison, or rabbit will make it less likely that your dog has food allergies.
According to board certified veterinary nutritionists – feeding a novel protein diet doesn’t prevent dog food allergies. What it does is make it likely that if your dog does have an allergy, it will be to a novel protein.
MYTH: rotating helps prevent your dog from being exposed enough to have a reaction.
However this is largely untrue – a dog can develop a reaction on the second or hundredth time they are exposed to a food. There is no way to predict that, so you might see a delay in onset, but it will not prevent the food allergies from occurring.
What rotation will do… Is if your pup needs to go onto a novel (or new) diet AND you have already rotated through all the common options found in a pet store – aka chicken, turkey, beef, fish, bison, venison, rabbit – you mind need to REALLY think outside the box to find a novel diet…
I’ve seen owners where they have to import Kangaroo, or special order Alligator to make homemade recipes during food elimination trials because their pup has been on so many different protein sources.
How do we recognize dog food allergies?
There are two basic ways food allergies present – one is with skin problems, and the other is with stomach or gastrointestinal issues.
Clinical Signs that Suggest your Pup May have Food Allergies
- Generalized (or Specific area), Non-seasonal itching: this can be ears, eyes, nose, legs, back, tail, paws, etc. But the key is that the itching is consistent – if your dog only itches in the winter or the summer months, it is much less likely that your pup will have food allergies. Because the food is consistent, the environment usually will change a bit with the season.
- Loose Stools: some pups with allergies will also have loose stools. This is because the dog is unable to digest the food properly due to the over-stimulated immune system which has caused inflammation within the gastrointestinal system.
- Vomiting: this tends to be very rare, and is usually associated with pups that not only have food allergies, but also have irritable bowel disease. However it can be seen with food allergies alone.
- Chronic Skin/Ear Infections: This usually goes hand-in-hand with chronic itching. If your pup is itching, it can cause breaks in the skin with allow for bacter or yeast to take hold. In some dog’s will food allergies the skin barrier actually becomes so inflamed that small holes are created in the skin which can allow things in from the environment that aren’t supposed to be there. Which can not only cause infection, but can cause chronic inflammation (in the form of red, irritated skin!).
How do we diagnose food allergies in dogs?
When a dog (or puppy) presents in the veterinary clinical with signs that point to food allergies usually what happens first is we TREAT whatever the current issues are. So if your pup has a skin infection – your veterinarian might start your pup on an antibiotic/antifungal/medicated shampoo, and something to help with the itching and inflammation while the skin heals.
STEP ONE: Treat initial symptoms
This initial treatment of symptoms is important – because if we start a food elimination trial to diagnose food allergies beforehand then we may never see improvement to clinical signs, even though your pup is actually no longer having issues related to food. Basically the skin infection or gastrointestinal problem can make itself worse even if the original stimulus isn’t there.
STEP TWO: Rule out other causes to symptoms
Depending upon your pup’s presentation your veterinarian might also do some laboratory testing – looking for other diseases such as Hypothyroidism, Cushings, Nutrient Deficiencies, External Parasites (like fleas or mites!), and more. This will allow your veterinarian to not only rule out other causes of symptoms, but other diseases that may inhibit the total resolution of your pup’s condition if we do find food allergies are the cause.
STEP THREE: Review all foods your pet has eaten
Next your veterinarian will take a thorough diet history – they are going to want to know EVERYTHING your pet has eaten, what they are currently eating, what they have eaten, when they switched from one food to the next. This history section can take awhile, and if you don’t have copy of ingredients list, it might take a bit to research all the individual food, treats, chews, and supplements.
If your pup has been on a lot of different foods your veterinarian might use a Saliva Test to see which foods your pup is currently sensitive to. Now this test is VERY DIFFERENT than a test for food allergies. These tests are known to be about 50% accurate. But if a dog owner has fed a ton of different food items (and can’t even remember which foods they have fed), a test might give some direction on where to start a food elimination trial.
STEP FOUR: Food Elimination Trials for Dog Food Allergies
A food elimination trial is where you feed a novel, or completely new diet with ingredients that your dog has never been on before for about 8 weeks. During this period of time your pup will not be allowed ANYTHING by mouth except for the novel diet.
Meaning that if your pup is on flavored medications – you may need to either give a non-flavored version of the medication, or you may need to give a topical form of the medication. This also applies to supplements. ANY supplement not completely necessary will be discontinued, and those considered necessary will be given in the most hypoallergenic form.
This also means – no treats, chews, toothpaste, water additives, etc. In order to have the most accurate results you want to LIMIT all the variables, and feeding other items than the food listed, will not results in a very accurate food elimination trial.
STEP FIVE: Reintroduction of potential allergens
After the trial period you will REINTRODUCE all the potential allergens on by one in 10-14 day increments. The reason you need to do the reintroduction is that not all dogs that respond favorably to a food elimination trial will actually have food allergies. They can have food intolerances or digestibility issues that have made a certain food item cause an inflammatory response. But once the body calms down and gets back to homeostasis – or balance – you can reintroduce that food item, supplement or medication without issue.
How to Choose a Novel Protein Diet for a Food Elimination Trial
Choosing the right food for your dog’s food elimination trial can literally make or break your results. In order to find a novel diet you first need to evaluate all the foods your pup has eaten before, this means pulling out your dog’s current food OR researching pet food labels online as to what ingredients your dog has been exposed to in the past. All of these ingredients are potential allergens to your dog.
The skin is a complex system – and what your dog has eaten over the last several months can affect how the skin looks and functions in this moment. Which is why we have to look at a longer period of time to see which foods may be causing a food allergy.
Exceptions to this are items that contain no protein – like vitamins and minerals. Allergies occur due the proteins within the food being identified as invaders – so vitamins, minerals – which contain no protein, are not of concern. Depending on the dog fats like fish oil, or chicken fat may be concerns (depending on how purified the oil is and how sensitive the dog). It’s best to just choose all new ingredients, just in case.
The next consideration you will need to make is what type of diet you want to use for your food elimination trial, there are several different types available to choose from. Your veterinarian or veterinary dermatology specialist should be able to guide you best as to which option you should choose. But know that the GOLD STANDARD will be a homemade complete and balanced diet.
Food Elimination Trial Diet Options:
- Over the Counter Novel Protein Diet
- Prescription Novel Protein Diet
- Prescription Hydrolyzed Protein Diet
- Homemade Novel Protein Diet
Each of these diet options has their own individual pros and cons associated with them. So let’s discuss these options in more detail…
Pros vs Cons of Diet Type for Food Elimination Trials:
Over the Counter Novel Protein or Hypoallergenic Diets:
These are probably the first thing most dog owners want to reach for to do a food elimination trial for their dog. They are usually the least expensive option, and are the most cost effective. What you should know is… These diets are the most likely to be contaminated with other proteins NOT listed on the label.
Several studies have been done doing PCR assays on over the counter hypoallergenic diets – and depending on the study – between 90-100% of the diets tested were contaminated with other protein sources not listed on the label.
For dog’s with very mild food allergies, or that can move from say chicken to a fish based diet – these differences might be fine. However for dogs that are very sensitive or that have been exposed to many proteins, using an over the counter diet is probably not a very good option.
Prescription Novel Protein Diets:
There are many different prescription novel protein diets on the market now – you can find these diets from Hill’s, Royal Canin, Blue Buffalo, and Purina Pet Care. Now what makes these diets potentially different than say an over the counter diet is that they undergo additional testing, and are produced using equipment that is solely for producing that pet food. Limiting the risk of cross contamination.
However these diets still do have a flaw in the sense that they are not usually a VERY limited ingredient. They usually contain five or more ingredients on the label, making the potential allergens more likely than a homemade, heavily restricted diet. For some dogs these diets will still have carbohydrate sources that their dog has been on before – and though carbohydrates are less likely to produce an allergic reaction than a protein like beef – it can still happen.
Prescription Hydrolyzed Protein Diets:
Another category of prescription diets is hydrolyzed protein diets – basically these diets are manufactured in a lab by taking proteins from things like chicken, then using hydrolysis to break down the protein into smaller pieces. By breaking the proteins down in this manner it basically bypasses the inflammatory process associated with food allergies. The protein is no longer considered an “invader” but is instead “novel” again.
Hydrolyzed protein diets are great for dogs who have been on multiple different proteins in the past, and is unable to prepare a homemade diet for their pet. Or is financially restricted from using a home prepared diet. However there are drawbacks to a hydrolyzed protein diet.
The first is that it doesn’t take into account the proteins in the carbohydrates – which can cause allergies in some dogs (though much less likely). The second is that according to research about 20% of dogs still have food allergy reactions to hydrolyzed protein diets if they are allergic to the protein.
Homemade Complete and Balanced Novel Diet:
The gold standard for food elimination trials is going to be the homemade complete and balanced diet. These diets are ideal for food elimination trials because you have the most control over the preparation, sourcing and ingredients within the diet. Meaning that you can create a DIY diet that is literally just ground bison with supplements. Now obviously this diet would not be long-term as we would want to get as much of our nutrients from whole food items as possible – however this approach can work really well for food allergies.
However the major draw-back of doing a homemade diet is going to be COST and TIME. It will take more time, and effort to home prepare your dog’s food. And it will cost more than a kibbled diet – on average I find most DIY diets using novel proteins (like bison, venison, or fish) can be two to three times as expensive as their kibbled diet comparisons. Time is the other aspect that is more difficult for those with busy families, or a lot going on.
If you are looking to home-prepare dog food probably the best resource I can give you is BalanceIT which allows you to make a custom recipe for your dog using their software. I’ve used it with clients many times to create recipes for food elimination trials. The reason why I like it is we can start off with a basic recipe – of say venison and squash – then slowly add ingredients one by one over time – all while using the same supplement (in different quantities) in order to keep the diet balanced. It can also allow you to work toward variety in the diet without having to constantly pay to reformulate a diet – like you would need to do if you were using a board certified veterinary nutritionist.
Once you know if your pup has a food allergy or not – by doing the food trial, and then having your dog flare if reintroduced to the food. Then you can work with a board certified veterinary nutritionist if you would like to create a recipe that includes organ meats and less supplementation. You can also use the software to work towards a pre-pared diet from a pet food company. Just keep in mind that cross contamination can definitely happen in the manufacturing process if foods are produced using the same equipment.
What do you do if diet change doesn’t work?
This is actually extremely common. Many food allergy trials do not actually find full resolution. And there can be a lot of different explanations as to why this happens. The first thing to consider is that during the food elimination trial you are looking for improvement, not resolution, and then worsening of symptoms after the food item is re-introduced. So if you do see that pattern – it suggests that a food allergy is at least part of the issue.
However if you do not see any improvement OR if you see minimal improvement, or improvement most of the time except for certain times of the year – your pup could actually have multiple different conditions. Some dogs will have both food and environmental allergies. If after doing a food elimination trial your dog is still having issues – be it mild or moderate – and things don’t see to be working. I would highly recommend seeking the assistance of a board certified veterinary dermatologist.
These are veterinarians that specialize in JUST skin, and are basically the itchy dog’s best friend. They are the best tools you have to getting to the bottom of your itchy dog problems – and getting that diagnosis. Once you have the diagnosis you can either continue with your dermatologist or you can bring on other practitioners – like integrative veterinarians – to help manage your dog’s condition.
In the future I will definitely be doing a deep dive into the different options for environmental allergy treatment, and the diagnostic process. But for now – I’ll just leave you with these tools – here is the directory for board certified veterinary dermatologists, and the directory for integrative veterinarians. These two resources can get you moving in the right direction. If you live in a place where specialists are not an option – please consider calling a couple specialists – some will do remote consults with you and your veterinarian to discuss your dog’s case.
As always – YOU are your dog’s best advocate – and as you learn and grow your knowledge base on all things related with canine health, nutrition and wellness – YOU will be able to evaluate the options presented to you and decide when one is the best for your pup. And YOU will also be able to seek out other options when needed.
I hope you all found this information helpful – if you did make sure to let me know! I love hearing from you guys! You can email me or contact me on Instagram any time if you have questions or if you found an interesting article for me to read!
About the Author: Nikki is a Registered Veterinary Technician (Veterinary Nurse) and Dog Mom with over a decade of experience with dogs and cats. Since graduation from college (BS Biology, AS Animal Health -2013) she has adopted two mixed breed dogs – Ranger and Ash, and has focused her time learning about pet food and nutrition.
Nikki shares information on a range of dog nutrition topics: from how to create a homemade complete and balanced dog food recipes, to how to choose a dog food. Nikki strives to give dog parents the information they need in order to make the best nutrition decisions for their pup!
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