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All dogs can benefit from a limited ingredient diet

Limited Ingredient Dog Food Diets have recently emerged in the pet food industry as a method to combat adverse reactions to specific ingredients included in the diet. It is important to clarify certain terminology within this emerging field of study. Food sensitivities can be classified under two categories: immunological and non-immunological disorders, Further than this, food allergy or food hypersensitivity is used to describe diet ingredients which elicit an immunological or immune-mediated response by the body and can vary on times of onset starting as early as within a few minutes of ingestion to several days after the initial ingestion. In contrast to this, food intolerance is used to describe diet ingredients that do not cause an activation in the immune system, and has various forms such as food idiosyncrasy, food toxicity, food poisoning, anaphylactic food reaction, pharmaceutical and metabolic food reactions.

Related to limited ingredient diets are hypoallergenic diets and gluten-free diets. Limited ingredient diets tend to focus more on food intolerances whereas hypoallergenic diets tend to focus on food allergies, however, there is significant overlap between these two diets. Related to both of them is the gluten-free diets.

History

Dogs experiencing health problems after consuming their food was first recognized as possible food allergies in the 1920s. It is believed that allergies develop when the dog is exposed to the same diet for a prolonged period of time.

Basis of Formulation

The goal of limited ingredient diets is to formulate a diet with a few ingredients as possible to lessen the risk of causing an immune-mediated response, which is most often noticed through allergenic-like symptoms the individual dog may display.

Beneficial Ingredients to Include in the Diet

Essentially any food ingredient can be included in a limited ingredient diet, as long as it follows FDA standards. According to the FDA, sufficient scientific data must be presented to indicate any health risks that could potentially be involved with feeding a specified ingredient or additive.

Majority of pet food diets contain a nutritional adequacy statement which ensures that the diet is complete and balanced for the labelled life stage. A common issue among limited ingredient diets, especially homemade diets, is meeting sufficient amounts of required nutrients in adequate ratios without causing imbalances which could potentially lead to deficiencies. Due to the difficulty in meeting all nutritional requirements, it is generally not recommended to feed homemade diets to young animals that are still growing as deficiencies are more likely to occur which can potentially have a negative impact on later life stages.

Added Omega-3 Fatty Acids

Omega-3 fatty acids, such as the EPA and DHA found in fish oils, provide a myriad of health benefits when included in the diet on a regular basis. These benefits include but are not limited to regulating the immune system to alleviate symptoms in regards to hypoactive or hyperactive immune systems, reducing inflammation as this is the primary self-defence mechanism against what can be perceived as foreign agents (i.e. ingredients in certain diets), improving skin and coat quality often seen to diminish when specific ingredients are not accepted by the body, and provide support to individual dogs with various health conditions such as kidney disease, heart disease, and cancer. Omega-3 fatty acids are most commonly found in whole fish and supplements derived from fish sources such as fish oil, krill oil, and cod liver oil. Although omega-3 fatty acids are often added to dry kibble diets, they are unstable and because of this, their benefits decrease over time. For maximum utilization of these benefits among many others, it is recommended to add liquid fish oils as a top-dressing to the dog's regular diet routine as per instructions on the bottle.

Hydrolyzed Protein Sources

Hydrolyzed proteins are commonly used in the human food industry as a source of readily digestible and utilizable protein sources, as well as flavour enhancers. Proteins that have been hydrolyzed into smaller peptide and amino acids reduce the molecular weight of the nutrient and thus can prevent the immune system from triggering an allergic response as the body does not recognize it as being a foreign substance. Through the use of hydrolyzing, the molecules are too miniscule to evoke a cross binding between Immunoglobulin E (IgE) on the surface of mast cells of the immune system thus preventing destruction of mast cells and avoiding IgE-mediated hypersensitivity reactions. However, due to the specificity of proteins only being able to interact with IgE antibodies, using hydrolyzed protein sources will not influence non-IgE forms of food allergies, such as IgA, IgM, or IgG. The most common hydrolyzed protein diets used to combat food sensitivities are based on chicken, fish, and most recently, soy. Currently in the dog food industry, hydrolyzed proteins are offered in Hills Prescription Diets, Purina Hypoallergenic Formulas, and Royal Canin Anallergenic Diets.

Novel Ingredients

Novel ingredients introduce pets to new ingredients which their gastro-intestinal systems have not digested previously. This means that novel ingredients are highly unlikely to exacerbate allergic reactions. However, pets can develop cross-reactivity to certain ingredients, for example being allergic to chicken can also predispose an individual to being allergic to other bird-meat species, and this can be attributed to the antigenic similarity between food allergens. Further studies reveal that even novel processing methods can change the way a dog responds to a particular ingredient. For example, protein denaturation can either eliminate allergenic determinants resulting in a decreased allergenicity, or expose new allergenic determinants resulting in an increased allergencicity. One form of protein denaturation is seen with Maillard Reaction Products, in which proteins combine with carbohydrates during the cooking process, as done during the pet food canning process. This may offer an explanation to the increased apparent allergencity of proteins in canned foods as compared to fresh protein sources in dry kibble formulations. Additionally, as more novel ingredients are being introduced, they are becoming common in traditional diets, which may lower the efficacy of the ingredient.

Mannan Oligosaccharides

Mannan Oligosaccharides (MOS) are an important ingredient that help to improve the health of the gastrointestinal tract. Mannan Oligosaccharides help increase the concentrations of beneficial bacteria, such as bifidobacteria, in the gut. This bacteria helps improve stool quality, which is often negatively affected by allergies. A healthy gut and beneficial bacteria also help support the immune system, which is especially important for dogs with allergies. An additional benefit of having MOS in the diet is that by promoting the growth of beneficial bacteria, it prevents the growth of harmful bacteria. Yeast cell walls are a source of MOS that can be used in dog diets.

Fructooligosaccharides

Fructooligosaccharides (FOS) are another important ingredient important for improving the health of the gastrointestinal tract. FOS helps to support the immune system by improving gut health and increasing the concentration of beneficial bacteria in the gut. FOS also helps to improve digestion and as a result helps improve stool quality and smell. FOS is especially important in the diet for dogs with allergies as the dogs often experience problems with their gastrointestinal tract. A common source of FOS found in dog diets is chicory root.

Specific Ingredients to Avoid in the Diet

Ingredients that do not meet FDA standards, or are shown to pose a health risk when fed to animals, may either be modified so that the health risk is alleviated or must be excluded from use in pet food diets. Specifically for limited ingredient diets, many common sources of allergenic-like symptoms should not be included in order to reduce the risk of eliciting an immune response.

Some of the major ingredients that dogs develop allergies to include: Corn, Wheat and Grain Products, Soy and Dairy Products, Eggs, Beef, Chicken

Other Less Common Food Allergens: Fish, Rice, Potato, Preservatives, Dyes

Any ingredient that provides the animal with protein has the potential to be an allergen. Allergies to certain ingredients develop when the dog experiences less oral tolerance to a protein source and when the lining of the gastrointestinal tract becomes damaged. This affects how the immune system responds to the ingredient and how well the protein is able to pass through the intestinal wall.

Animals Who Can Benefit from Limited Ingredient Diets

These spaniel mixes would benefit from a limited ingredient diet

There are several specific breeds of dogs who are known to be predisposed to food-borne allergens, which can be attributed to a number of factors regarding breed, age, and gender. However, there is no specific sex, breed, or age that results in a food allergy . Some breeds are more at risk for food reactions: Soft-Coated Wheaton Terrier, Dalmatian, West Highland White Terrier, Collie, Chinese Shar-Pei, Lhasa Apso, Cocker Spaniel, English Springer Spaniel, Miniature Schnauzer, Labrador Retriever, Boxer, and Dachshund , , . Among purebred dogs, it has been found that the German Shepherd and the Golden Retriever have more food reactions than any other purebred dogs . Crossbreds may be at a lower risk for food allergies . It is know that Irish Setters are genetically prone to gluten-induced enteropathy, which results in the dog developing a gluten sensitivity to wheat and other grains . Therefore, Irish Setters and other breeds that are more at risk for food reactions would benefit from a limited ingredient diet.

Food allergies mostly cause gastrointestinal and dermatologic symptoms. Gastrointestinal symptoms include vomiting, diarrhea, abdominal pain, and increased fecal frequency . The German Shephard, Irish Setter, and Shar-Pei are more frequently affected by gastrointestinal symptoms due to food allergies . The most common dermatologic symptom of a food allergy is itching . Other dermatologic signs involve skin lesions, which include papules, erythema, excoriations, epidermal collarettes, hyperpigmentation, pododermatitis, seborrhea and otitis externa . Otitis externa is a very important indicator of a food allergy and in some dogs it is the only sign of an allergy . Dogs experiencing gastrointestinal or dermatological symptoms will benefit from a limited ingredient diet. A limited ingredient diet can help owners to determine a particular ingredient that is causing the allergy or at least help the owners to narrow it down to a few possible ingredients to avoid. Gastrointestinal or dermatological symptoms should improve once the ingredient or ingredients have been removed from the diet. Thus, identification of the ingredient causing the allergy can be done using a diet that lacks a specific ingredient with a subsequent challenge using a diet that contains the ingredient. Limited ingredient diets are also helpful for dogs showing signs of Inflammatory Bowel Disease or other gastrointestinal tract issues .

Other Feed Formulations Related to Limited Ingredient Diets

Hypoallergenic

Many pet parents try an “elimination diet” in attempts to source the exact allergen or food ingredient that the individual dog is not responding well to. This is initiated with basic and essential ingredients and progress by adding varied ingredients until allergy symptoms reoccur, but always making sure the symptoms are not from a lack of a required nutrient. When attempting to find the allergen it is beneficial to use home cooked diets as it is easier to control the ingredients . Limited ingredient diets can be used as an alternative to homemade diets in certain situations such as when the dog is too large that a homemade diet becomes too expensive, or when the dog cannot tolerate or does not like the homemade diet .

Gluten-Free

Gluten-free diets are becoming more popular among dog owners around the world. Like in humans, gluten has been linked to many health conditions in dogs. Gluten sensitivity in dogs results in similar symptoms as food allergens do. Gluten sensitivity is believed to cause skin problems and problems with the gastrointestinal tract . Celiac disease has even been reported in dogs, specifically the Irish Setter, while most breeds only develop sensitivities .