Food Allergies 101

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Food Allergies 101
Nothing to sneeze at: food allergies in dogs.

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Is your dog itching and scratching? Does she have frequent ear infections or poor coat quality? You could be contributing to your dog’s distress without knowing it if she’s allergic to what you’re feeding her. Food allergies are a rising concern with dog owners and it seems like more and more dogs are suffering from them.

But what exactly is a food allergy?

Food allergies are different from food intolerance. Food intolerance is the result of poor digestion, such as lactose intolerance. People and dogs with lactose intolerance are either missing or have low levels of the milk digesting enzyme lactase.

Food allergies are the over-response of your dog’s immune system to an invading protein. In the case of a food allergy, this protein is contained in your dog’s food. Proteins are present in most of the foods your dog eats. While most people recognize that meats are a source of proteins, there are also proteins present in grains and vegetables. Any one of these proteins has the potential to cause a food allergy.

Your dog’s gastrointestinal system (mouth, stomach, intestines) protects her from potential allergens each day. Approximately 70 percent of the body’s entire immune system is centered in the gastrointestinal tract. When your dog eats a meal, the food is first digested in the stomach. The large pieces of food are broken down into smaller pieces by stomach acid and then enzymes and stomach acid work together to break the complex protein structures down into smaller structures. The partially digested food then moves into the small intestine. The food is further digested until the proteins are broken down into their smallest parts, amino acids, which can then be absorbed into the body through special cells called enterocytes. Enterocytes act as both a welcoming hostess to amino acids that they like and want, and as bouncers (door guards) for amino acids they don’t like. When a whole protein is absorbed in the intestines instead of being broken down first, the immune system reacts and your dog shows symptoms of a food allergy.

When the System Works

The intestinal tract’s ability to prevent the absorption of whole protein is dependant on the health and integrity of the mucosal barrier. It is the proverbial guardian of the body at the gastrointestinal gate. The mucosal barrier (lining of the gut) is comprised of both structural components and immune system components. The structural components physically prevent the absorption of large proteins. The immune system component is responsible for recognizing potentially harmful contents of the gastrointestinal tract. The health and integrity of the gastrointestinal tract is dependant on the normal structure and function of the enterocytes, effective protein digestion, and the presence of the dog’s immune cells (called IgA cells) in the gastrointestinal tract.

The Gut and Immune System Together
Prevent Food Allergies

IgA cells are a type of immune cell secreted in the intestine. Some of the IgA will float freely in the contents of the intestine while other IgA attaches to the wall of the intestine to prevent whole protein from coming in contact with the enterocytes. Just like volleyball players they bounce whole proteins back into the contents of the intestine for more digestion. The more effective protein digestion in the stomach and intestine is, the smaller the proteins are when they come in contact with the IgA. Small proteins and single amino acids do not get bound to the IgA and are allowed to pass by the IgA and be absorbed into the body as nutrients.

At a Glance

Some of the breeds most prone to food allergies include: Boxer, Cocker Spaniel, Springer Spaniel, Collie, Dalmatian, German Shepherd, Lhasa Apso, Miniature Schnauzer, Retriever, Shar Pei, Soft-Coated Wheaten Terrier, Dachshund, and West Highland White Terrier

Most common food allergens include: beef, dairy, and wheat.

Least common food allergens are fish and rabbit.

General signs and symptoms of allergies include: dry itchy skin, excessive scratching or licking, bald patches, a high frequency of hot spots, ear infections, skin infections, diarrhea, and vomiting.

When the System Fails

Malnutrition can affect enterocyte structure and function. A poorly functioning or damaged enterocyte can let whole proteins into the body. Once a whole protein has managed to breach all of the gut’s defenses, gut-associated lymphoid tissue (GALT) takes over. GALT can prevent the body’s natural immune response to a foreign protein. Most of the time this is what happens, but in the case of food allergies, GALT does not prevent the immune response and an allergic response (immune hypersensitivity) is formed.

Unfortunately, every time the food is eaten, this over-response of the immune response becomes greater. So continuing to consume the diet that caused the allergic response results in a greater and greater response every time. After this hypersensitivity is formed, each time the dog eats the food, mast cells in the body’s immune system release hertamine. If this hertamine release is large enough, it may manifest as diarrhea, itchy skin, chronic skin infections etc.

Isolating the Problem

The first thing you need to do is work with your veterinarian to make sure that your dog’s symptoms truly indicate a food allergy. If that’s the case, your vet will likely recommend that you try an elimination diet— feeding a food that has a different protein (meat) source and a different carbohydrate (grain) source than what your dog has had before. Common anti-allergy foods (novel protein sources) include kangaroo and oatmeal or venison and potato. This prevents the immune response from continuing to be triggered.

Your vet may also suggest that you try a hypoallergenic diet. These foods are made with hydrolyzed proteins. That means that the proteins are already broken down into pieces that are small enough that IgA won’t bind to them and they won’t trigger an immune response.

Lamb and rice foods used to be considered “hypoallergenic” when most commercial dog foods were made with chicken or beef and corn or wheat. Since most dogs had never had lamb or rice before, it was a good option for dogs that experienced allergies while eating a regular food. Now, however, many dogs are showing allergies to lamb and rice diets. This is to be expected since an allergy can develop to any diet. If your dog is allergic to lamb and rice you may need to find a food with different ingredients such as fish and oatmeal, or venison and sweet potato.

While your dog is on any special diet, it’s very important that she doesn’t get any other food such as cookies, treats, rawhides, people foods, etc. Since you don’t know yet exactly what she is allergic to, you don’t want to give her something other than her food and trigger the allergic reaction. Once you’ve got her on a food that she is not reacting to, you can start to reintroduce other foods. If your dog reacts, you’ll know exactly which food (or foods) causes the problem.

Preventing Food Allergies

Is there anything we, as owners, can do to avoid food allergies from developing? This is one of the toughest questions in dog nutrition today. While we still don’t really know how to prevent allergies entirely, there are things you can do that may help your dog fight off numerous allergies.

Promote a healthy mucosal barrier. This can be done by ensuring that our dogs, and especially puppies, have adequate nutrition and health care.

Watch out for gastroenteritis. There have been some theories that early gastroenteritis or severe gastroenteritis, especially in puppies or young dogs, can result in an adult dog that is more likely to develop food allergies. Preventing gastroenteritis, in theory, is easy— just don’t let your dog eat anything but dog food and treats. In actuality, this is much harder to deal with. Dogs eat a variety of things, some that are not harmful—grass, dirt, bark, wild berries (i.e., raspberries, strawberries), sometimes a little cow or horse dung—and some that are not good for them (rotten garbage or dead animals). It can be very hard to police what goes in your dog’s mouth.

If you suspect that your dog has gotten into garbage or eaten something that may cause tummy upset, it may be best to feed your dog a low-protein diet (boiled white rice or potato) until the suspected tummy upset passes or you consult your vet. In general, if diarrhea lasts more than 72 hours without signs of getting better or if the diarrhea seems especially severe or malodorous, you should consult your vet. In these cases, do not attempt to treat the dog yourself with over-the-counter medications because diarrhea is the body getting rid of bad things in the gut. To give something that stops the diarrhea can result in keeping the bad things in the gut and causing a serious illness.

Promote effective protein digestion. In general, your dog should have no problem digesting protein. If you are feeding a homemade cooked or raw diet, grinding or blending your protein source in a food processor can be helpful in improving protein digestion. In kibble-fed dogs, the protein is already ground before it is kibbled so there is no need to grind it.

Choose a dog food with exclusive protein sources. A food that only has one or two protein sources can be helpful in giving you more choices later on should your dog develop an allergy. For example, if you use a food with five protein sources (i.e., turkey, chicken, duck, salmon, and tuna) and your dog develops an allergy to it, you now have to find a food that doesn’t contain any of these protein sources. This can be challenging. Conversely, if you feed a diet with chicken as its sole protein source and your dog develops an allergy to it, you can easily find a diet that doesn’t contain chicken.

Preventing food allergies may be impossible in dogs that are prone to developing food allergies. Some breeds are becoming noted for food allergies (see sidebar p.82). As a result, it is possible that a propensity for developing food allergies may be genetic, in which case, we should avoid breeding dogs that have food allergies.

Don’t Give Up

Dealing with a dog with food allergies can be challenging and disheartening. Proper diagnosis of food allergies can make it easier and understanding why food allergies start can help us prevent future allergies from starting. On a personal note, my Labrador has had food allergies all his 12.5 years. It has been a long road and often a difficult one. It is so much easier to find novel protein sources now than it was 12 years ago. If you have a dog with allergies, take heart, it will get better.

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Comments (16)

Our family dog suffered from constant itching and scratching, our vet recommended various prescriptions that had limited to no effect and produced some harsh side effects. The frustration was overwhelming until we discovered VitaHound Daily Supplement, introduced to my wife by her horse riding friends who had several dogs with healthy coats. I have looked for the supplement at several pet stores but it seems to only be available at www.vitahound.com or maybe your veterinarian. This article confirms the claims reported on their site, so I was happy to see their marketing to be legitimate.
Mon, 05/07/2012 - 14:34
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Fri, 06/14/2013 - 05:23
Our clinic specializes in canine allergies, for this reason one of our patients directed our staff to this article. Bravo for Modern Dog writing on the subject in manner that is accurate but most importantly clearly explains this common condition that numerous dogs suffer from. The comment from our colleague pointing out that any food ingredient can become a food allergen is about the most important aspect of the canine digestive physiology that dog owners need to understand, for reason the best non-steroidal remedies involve digestive aid supplements. The dog supplement from VitaHound, I have seen advertised in this magazine works well in combination with a dog food brands like Blue Buffalo, in fact I believe the new Blue Buffalo brand Freedom copied several of the VitaHound formulations ingredients, nevertheless the more dog owners understand about their dog’s health the better owners and patient advocates they become.
Sat, 06/16/2012 - 12:35
I found this article very interesting and putting the problem in fair laymen's terms for all who read it. The problem I see with testing any animal or human for that matter to see allergic reactions must be done under controlled conditions due to severe allergic reactions and medication injectioned to stop the reaction immediately. Therefore not recommend doing on your own. Sad things have become so expensive, there should be researchers that would have great information if people joined their study groups on reactions to foods, environmental issues etc. My friend has a dog I am researching information for and came across this article.
Thu, 09/20/2012 - 15:01
Your pet may also suggest a prescription food. To transition your pet to the new food, mix a small amount of the new food with the current food and increase the new food over the course of 10 days. <a href="http://www.bookdes.com/2012/08/delicious-dog-diet.html"><b>Healthy Diet For Dog</b></a>
Sun, 11/04/2012 - 00:23
Thank you again for the how to advice on raising my dogs. This article in particular has brought clarity to the various research sources I have been studying on dog food allergies and allowed me to effectively advocate for my dog's care. Secondly, I thank you for the dog supplement you guys recommended from www.vitahound.com in an earlier issue, their formulation has relieved the itching and shedding my dog's where suffering from. Please continue to spend the time and effort to publish comprehensive pieces on dog health and various care methods.
Sun, 01/06/2013 - 19:36
I have a 8 year old labb , with allergies .what food do you reccomend?
Wed, 03/13/2013 - 23:54
There are no allergy-safe dogs.There are no non shdideng dogs.There are dogs that are low shdideng (like the list above me), but have to be groomed more often. It is also not usually the hair people are allergic to but the dander and salvia. There are many breeds that tend to be good for people with allergies.The problem is, not all allergies are the same. One breed that many not affect my allergies may be intolerable to someone else. The person needs to spend time with the breed they are interested in to find out if they can tolerate them. Also, becareful of the poo or doodle mixes. Just because they are part Poodle (one of the more allergy friendly breeds) does not mean they will inherit that trait. Some will and some wont'. So you may meet one that is ok for your allergies, then buy one only to find out that one isn't.There are many of these mixes in rescues and shelters because they are advertised as hypoallergenic only to be taken home and found they are not.
Wed, 04/03/2013 - 11:05
A great way to relieve your pet’s skin irritation from an allergic reaction is to use essential oils. There’s a product out there that I highly recommend. It’s called CalmCoat Topical Spray. It’s an all natural product that will relieve the irritation, promote healing and encourage hair re-growth. It’s an amazing product. http://www.calmcoat.com/calmcoat_natural_spray.html

Keep in mind that allergies are usually controllable but not CURABLE. There are environmental allergens (house dust mites, food storage mites, pollens [grasses, trees, weeds]) and food allergens. The first step is a good examination and evaluation by a veterinarian. In terms of people promoting grain-free diets, keep in mind that food allergies usually involve proteins, not as frequently carbohydrates. For a food trial, it's best to have a single protein source and a single carbohydrate source (or a hydrolyzed protein diet) that the dog has NEVER eaten (referred to as a “novel protein” and “novel carbohydrate”). A commercial diet is not the best for a trial. A commercial manufacturer makes all of its foods in a single production facility and doesn't clean out the production line when it changes to a different food. It may have produced a beef-based diet and then changes to a chicken diet but pieces of the beef food can be found in the chicken-based food. NOT GOOD IF YOUR DOG IS ALLERGIC TO BEEF!! Studies have documented this problem in most diets. So use a prescription food for the trial and if it solves the problem, talk to your veterinarian about a similar commercial alternative. If your pet has a flare up, you need to go back to the prescription product. Prescription food manufacturers either have a dedicated production line for a particular diet or do a complete clean out of the production line before switching to another food (that's why they are more expensive). Flavorings or ingredients can also be a problem. Heartgard for prevention of heartworms (a widely used medication), for example, contains beef. So dogs allergic to beef will have problems even when it is only given once per month. Vitamins, supplements, and other flavored drugs and treats can also be a problem.

Allergy testing is a good consideration for environmental allergens. If allergies are a significant problem, "allergy shots" or hyposensitization can be a good consideration and can often provide significant relief but one again, not a cure. There are no reliable tests for food allergies other than a dietary trial or elimination diet which must be fed for a MINIMUM of 3 months (and if improving, some pets may require up to 4 months on the diet).

Keep in mind that animals with allergic tendencies may have more than one type of allergy. For example, an animal may have a food allergy (usually a year-round problem while the food is being fed) and in addition be allergic to tree and grass pollens (which would be a problem in spring when trees pollinate and summer when grasses pollinate) and thus get worse in spring and summer.

Dr Don Doss
Mon, 05/06/2013 - 15:11
Help! My dog has MANY food allergies. Beef, chicken, dairy, beets, wheat, lamb, brown rice, etc. She also has seasonal allergies. She is on a strict venison and sweet potato or fish and potato diet. I keep trying to introduce a new food ( like oatmeal or goat or rabbit) but her ears get inflamed. My question is, how soon after she eats a new food will I see a reaction? It's always painful ears. I can never tell if it's the food or environmental. Sometimes it's several days before her ears hurt. Would I see the reaction within hours? Or could it be days? She is a 10 yr old Jack Russell. She had kibble for most of her life then we switched to raw with the help of a wonderful vet. When we discovered all the allergies, she went on the elimination diet (Nature's Balance) Thanks so much for any help you can offer!!
Fri, 09/06/2013 - 10:06
hypoallergenic dog foods, commercial or homemade. i'd prefer homemade. but if the owner is a busy individual, then go for commercial.

you might find this site useful:


http://sweb2.dmit.nait.ca/kcaberte1/HypoallergenicDogFoods/
Tue, 09/24/2013 - 12:13
hypoallergenic dog foods, commercial or homemade. i'd prefer homemade. but if the owner is a busy individual, then go for commercial.

you might find this site useful:


http://sweb2.dmit.nait.ca/kcaberte1/HypoallergenicDogFoods/
Tue, 09/24/2013 - 12:15
What are your sources for this article?
Thu, 09/26/2013 - 16:33
My dog has severe allergies to animal and soy protein. The only thing that has worked for us is a vegan diet. Our vet initially recommended a prescription vegetarian food. We are currently feeding her Natural Balance's Vegetarian kibble and canned--and it does not require a prescription. This food does not contain any animal or soy protein.
Wed, 11/06/2013 - 12:26
What is "hertamine"? In your article you claim "mast cells in the body’s immune system release hertamine. If this hertamine release is large enough, it may manifest as diarrhea, itchy skin, chronic skin infections." I have taken chemistry, biology and anatomy and have yet to learn about hertamine? What are your sources for information pertaining to this unique chemical?
Sat, 11/23/2013 - 07:37
Should probably run this through spell check one last time. "Dependent" is misspelled "dependant" twice.
Sat, 02/08/2014 - 17:46

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