Just like us, dogs can be allergic to something in their food. Adverse reaction to food is defined as an abnormal response to a food or food additive. There are two classes of adverse reactions: those in which the immune system is involved (generally called food allergies); and those that occur without an immune component (generally called food intolerances). There are many additives in commercial pet food that can cause allergic reactions in dogs. Feeding your dog, the same food every day, year after year, will increase the chances of the immune system reacting to one of the components in the food. Commercial pet foods are full of fillers like soy, potato, starches, wheat gluten etc which are not biologically appropriate for dogs, and can stress out their immune system. This chronic stress can develop in to hypersensitivity or gut dysbiosis leading to adverse food reaction. 

What does a food allergy look like?

Food allergy is defined as an immune-mediated reaction following food intake. Allergies are exaggerated immune responses to food particles. Food allergies often look like skin diseases. Food allergies usually do not affect a dog’s respiratory system, but manifest as something similar to atopic dermatitis. 

Signs of Food Allergies:

  • Itching & scratching (generalized or focal), bumps on skin, odor, red sore skin and secondary infections
  • Swelling & inflammation, with or without secondary infection
  • Bacterial or Yeast infections – as dogs scratch their itchy skin, they can get relapsing secondary infections when bacteria or yeast comes in contact with the inflamed skin. 
  • If corticosteroid treatment does not help beat the symptoms, it can mean that the issue is food allergy related. No response to other treatments is also one of the signs of adverse food reaction.  
  • Recurrent ear infection 
  • Diarrhea, Vomiting, or subtle manifestations such as increased frequency of defecation, soft-formed stool, flatulence etc
  • Certain comorbidities are also reported such as nasal discharge, respiratory distress, hypersalivation
What causes food allergy in dogs:

Food induced diseases can be due to hypersensitivities (IgE mediated), toxic reactions after ingestion of substances such as mycotoxins, xylitol etc, or metabolic reactions (from lactose intolerance, gluten sensitivity etc). Food induced hypersensitivity reactions can occur due to poorly digested protein. You might think your dog is a carnivore and cannot be allergic to meat. But most often dogs are allergic to animal meat protein sources such as chicken, beef as well as eggs, cow’s milk, soy, wheat etc. Beef, dairy products and wheat are most commonly reported as ingredients causing adverse food reactions in dogs. Proteins are changed into substances and recognized by the immune system as foreign invaders to be attacked. The resulting inflammation leads to gut issues, and skin disorders.

An incompletely digested food protein has the potential to incite an allergic response. Food proteins cross the intestinal mucosa in small but significant amounts despite mucosal barrier. Gut dysbiosis can also predispose dogs to food allergies. If the mucosal barrier gets more permeable, poorly digested protein will pass through, leading to adverse reactions and inflammation. IgE mediated food allergies are most common, with repeated food allergen ingestion leading to reactivity and atopic dermatitis.

Food elimination diet trial:

A food allergy can’t be cured but symptoms can be avoided by limiting your dog’s diet and not allowing them to eat the foods they are allergic to. Because most food allergens are glycoproteins, dietary protein sources should be evaluated & managed first. Prevent exposure to allergens by following these steps:

  • Add new ingredient/food gradually to avoid gastrointestinal distress. You can ask for a prescription hypoallergenic dog food from your Vet. But, elimination diet trials with homecooked food are more effective because you can have more control over the ingredients fed. 
  • Introduce novel protein – Feed a protein that your dog’s digestive system has not been exposed to. Food used for allergy trials must contain one protein and one carbohydrate source and neither can be something the dog has had before. 
  • Add Omega-3 fats – as they have immunomodulating and anti-inflammatory properties. Fish oil & Fatty fishes are good sources of EPA & DHA (essential omega-3 fatty acids)
  • It is important to keep your dog’s meals simple with no unnecessary ingredients. Feeding too many ingredients will make it hard to identify the allergens.  
  • The recommended duration for elimination trials is usually 10 weeks minimum in order to ascertain and identify all allergic ingredients. Ideally, a nutritionist should be involved in formulating the diet.
  • Hydrolyzed protein diet – This method uses the conventional and common protein sources, but it is broken down into small molecules. This makes it more difficult for the immune system to detect and react against. These diets may be categorized as partially hydrolyzed or extensively hydrolyzed. Extensively hydrolyzed diets are less likely to cause adverse responses, even in dogs allergic to their source protein. 
  • How thorough an avoidance of food ingredients should be depends on the individual dog and it’s sensitivity level. Some dogs may suffer adverse reactions to even small quantities of the food or food additive, whereas others may have a higher tolerance level.
Treating allergic reactions:

Your Vet can alleviate your dog’s allergy symptoms by treating with antihistamines, and treating secondary skin infections with antibiotics, antifungals, or ear medications. Your vet will prescribe the best treatment based on your particular dog’s needs and condition. 

Natural ingredients for allergies:

  • Natural antihistamines such as nettle leaf powder, quercetin (found in apple skin, berries), vitamin C rich food (such as bell peppers, kiwi, broccoli etc) can also be fed to reduce itching. 
  • Inflammatory skin condition can be dealt with by feeding ginger, honey, and turmeric in moderation. This will also help in managing the allergic responses. 
  • Make a spray of green tea and Apple cider vinegar diluted in distilled water. Use it once or twice a day on yeast infections or inflamed skin.
Dealing with food allergies can be frustrating & complicated. Identifying a food allergy and changing your dog’s diet to treat it takes time. The best way to prevent food allergies is by feeding a balanced and species appropriate diet to your dog.