Food allergies and environmental allergies in dogs differ on several levels. In fact, the only thing they have in common is the mechanism – both occur due to the immune system overreacting to otherwise harmful substances.
In this article, we will discuss the differences between food and environmental allergies in detail and based on several criteria, including incidence, exposure method & triggers, risk factors, signs & symptoms, diagnosis, and treatment.
Another difference between food and environmental allergies is their incidence. Namely, environmental allergies are far more common than food allergies.
Despite having a notorious reputation, food allergies are not nearly as common as owners believe. In fact, according to the Tufts University Cummings School of Veterinary Medicine, only 10% of dogs coming to vet clinics for food allergies turn out to really have one.
More accurately, a 2017 study showed that only 1-2% of dogs seeing vets for any diagnosis have food issues. In dogs seeing vets for skin diseases, the number is a bit higher, or 6%.
In most cases, the symptoms are due to food intolerance (an adverse food reaction that does not include the immune system). The culprit can also be the food preparation method or the food’s nutrient ratios – too much fat or not enough dietary fiber.
Exposure & Triggers: Food Vs. Environmental Allergies
Dogs with food allergies develop a reaction when eating the offending food. In a 2016 study, the top offending foods for dogs are:
- Beef – 34%
- Dairy products – 17%
- Chicken – 15%
- Wheat – 13%
- Soy – 6%
- Lamb – 5%
- Corn – 4%
- Egg – 4%
- Pork – 2%
- Fish – 2%
Dogs with environmental allergies react upon inhaling the allergen (just like humans), but also if coming into contact with the allergen through the skin and paws. Common environmental allergens for dogs include:
- Grass, weed, bush & trees pollen
- Mold spores
- Human & pet dander
- Dust & dust mites
- Cigarette smoke
- Perfumes
- Cleaning products
Food allergies are a year-round (non-seasonal) problem, while environmental allergies are seasonal (at least in most cases).
Risk Factors: Food Vs. Environmental Allergies
So far, the only risk factor for food allergies is genetics – if the parents are sensitive, the offspring is at higher risk of being sensitive too.
A 2007 study showed that when it comes to food allergies in dogs, there is “no breed, sex or age predilection, although some breeds are commonly affected.”
The term “dog food allergies” is often googled in conjunction with several dog breeds, including Dachshunds, Golden Retrievers, Bulldogs, German Shepherds, Pugs, Pitbulls, Cocker Spaniels, West Highland Terriers, Yorkshire Terriers, Shih Tzus.
On the other hand, when it comes to environmental allergies, there are several risk factors. Here are some risk factors according to VetLexicon:
- Living Location: Dogs living in urban areas are more likely to have allergies than dogs in rural areas. This is confirmed by several studies, including one from 2018 and one from 2020.
- Month of Birth: Dogs born during pollen season can get sensitized in the first few months of life.
- Parasites: Heavy infestations with intestinal parasites may also play a role in triggering or suppressing allergic reactions. A 2015 study describes the parasite-allergy relation as a paradox.
- Infections/Vaccines: Viral infections and vaccines can stimulate the dog’s body to produce IgE against environmental allergens, thus acting as risk factors for allergies.
Signs & Symptoms: Food Vs. Environmental Allergies
While often overlapping, the clinical manifestation of food and environmental allergies can differ.
VCA Animal Hospitals explains that food allergies trigger the following common signs and symptoms:
- Itchy skin, paws, or ears
- Digestive disturbances (vomiting, diarrhea)
According to PetMD, environmental allergies manifest with:
- Scratching and biting
- Inflamed and infected skin
- Excessive shedding
- Paw licking
- Scooting or licking the anal region
- Chronic ear infections
- Respiratory issues
Interestingly, a 2019 study demonstrated that dogs with allergies can show bad habits such as “mounting, chewing, hyperactivity, eating feces, begging for and stealing food, excitability, attention seeking, and excessive grooming.”
Diagnosis: Food Vs. Environmental Allergies
Diagnosing allergies in dogs is challenging and differs based on the allergy type. Food allergies are diagnosed via elimination diet trials. This is because skin and blood testing are not accurate for food allergies.
During the elimination diet trial, the dog is fed a simple, limited-ingredient diet containing a novel protein (a protein the dog has never eaten before) or hydrolyzed protein (broken down into pieces that are too small and can escape the immune system’s sensors).
Dogs can also be fed a homemade diet. That way, owners know exactly what goes into the meal (a 2010 study showed that some commercial foods contain proteins that are not listed on the label). However, this is not sustainable in the long run, especially for large dogs.
Environmental allergies can be diagnosed via skin and blood testing. Skin testing is also known as intradermal allergy testing and includes injecting small amounts of allergens into the dog’s skin. It is considered a golden standard for diagnosing atopic dermatitis (a specific type of allergy in dogs).
Blood testing is less invasive and does not require anesthesia and shaving. On the downside, it may yield false positive results. To do blood testing, the vet will draw blood from the dog and send it to a laboratory for analysis.
Treatment: Food Vs. Environmental Allergies
Both food and environmental allergies result in secondary skin issues (wounds, infections, hot spots) that require proper treatment. Other than that, treatment is quite different.
For food allergies once the offending foods are determined for food allergies, the management includes a diet free from those allergy-causing ingredients.
For environmental allergies, things are not so simple. Managing environmental allergies in dogs requires a complex and multimodal approach:
- Bathing: Dog shampoos and conditioners for allergy management feature soothing and anti-itch active ingredients. Plus, bathing mechanically removes the allergens from the dog’s coat.
- Cleaning: Keeping the house and dog’s environment clean is also vital. This includes dusting, vacuuming, and washing the dog’s bed, bowls, and toys regularly.
- Oral Medications: Based on the severity of the symptoms, there are many options, such as antihistamines, steroids, cyclosporin (Atopica®), and oclacitinib (Apoquel®). It may take some experimentation to determine which drug works best.
- Injectable Medications: There are injections with interleukin 31 antibodies (Cytopoint®, Cadi®) that block the itch signals and prevent them from reaching the brain, thus relieving allergy symptoms.
- Immunotherapy: Also known as desensitization therapy, involves injecting the dog with small amounts of allergens over a prolonged period to make the immune system less sensitive. However, immunotherapy is ineffective in almost half of the cases.
- Supplements & Home Remedies: Finally, many supplements and home remedies can be used in conjunction with mainstream treatment. Popular options are omega fatty acids and CBD oil for dogs. Dogs Naturally Magazine recommends bovine colostrum, apple cider vinegar, bee pollen, herbs (nettles & astragalus), and quercetin.
Conclusion: Food Vs. Environmental Allergies
While there is certain overlapping between food and environmental allergies in dogs, the two conditions are pretty different. Those differences reflect on several levels and hugely impact the outcome – management success.
If you suspect your dog is suffering from allergies, schedule an appointment with your trusted vet and get to the bottom of the problem or get one of the dog allergy tests. Allergies are hard to live with and have an impact on both your and your dog’s quality of life.
