The Difference Between Food Allergies and Environmental Allergies in Dogs

Written by Small Door's medical experts

If your pup suffers from itching, hair loss, skin infections, or ear infections, she may have allergies. But does she have a food allergy, seasonal allergies, or both? The symptoms may be similar, but they require different treatments, so read on to learn more about how to identify and deal with canine allergies.

In This Article

Allergies in dogs

Just as they are for people, allergies in pets are an exaggerated immune response to something in the environment that shouldn’t trigger one.

People with seasonal allergies often sneeze and get runny noses, but allergies generally don’t affect dogs’ respiratory systems. Instead, canine allergies cause lots of skin problems, such as atopic dermatitis. It’s common for dogs with allergies to suffer from chronic ear infections and itchy skin, especially on the face, paws, armpits, and lower belly. Unfortunately, because dogs tend to scratch and chew on their itchy spots, they can get secondary infections when bacteria or yeast come into contact with irritated skin. Allergies in dogs can be classified into two major types: food and environmental.

[#seasonal]Seasonal and environmental allergies in dogs

Environmental allergens for dogs include pollen, molds, grass, trees, and dust mites. Another common allergen is flea saliva, which causes a disease called flea allergy dermatitis.

If you notice that your dog suffers from itching and scratching during a particular time of year, or in response to being in a specific place, keep notes. Diagnosing allergies tends to involve a lot of trial and error, so having as much information as possible will be helpful for your veterinarian. 

To help manage your dog’s environmental allergies, you can also try giving them regular baths, to help wash away external allergens from the skin and coat.

Diagnosing allergies tends to involve a lot of trial and error, so having as much information as possible will be helpful for your veterinarian.

Food allergies in dogs

Food allergies account for about 10% of allergies in pets. Although it may be surprising to hear, since you probably think of your dog as the ultimate carnivore, the most frequent allergy culprit is a protein, usually chicken or beef. But certain dogs can also be allergic to carbohydrates, preservatives, or food dyes. 

Food allergies are typically addressed by changing your dog’s diet to limit the ingredients they consume. A limited ingredient diet might involve feeding them a ‘novel’ protein (that your dog has never eaten before), such as rabbit or venison, and/or another carbohydrate source, such as green peas. In addition to chronic itching, food allergies can cause gastrointestinal problems like diarrhea.

Food allergies vs. seasonal and environmental allergies in dogs

Environmental allergies and food allergies often present similar symptoms which include:

  • Itchy skin that flakes

  • Ear infections

  • Stinky ears

  • Hair loss or bald patches

  • Head shaking and scratching of the ears

  • Excessive licking and biting of the paws

  • Hives

  • Face rubbing

  • Hot spots

  • Sneezing

  • Scratching

  • Eye discharge

  • Respiratory problems

The main differences between food allergies and environmental allergies are: 

  • Environmental allergies may come and go with the seasons

  • Food allergies can cause gastrointestinal issues that include chronic gas, diarrhea, or vomiting 

Since so many symptoms overlap between each type of canine allergy, it’s best to check with your veterinarian instead of assuming allergies may be one or the other.

Can I get allergy testing for my dog?

Yes! In fact, as it’s very difficult for owners to differentiate between environmental and food allergies themselves, a vet visit should be the first step in treating your dog’s allergies.

Once you bring your pup into the clinic, the veterinarian will ask you some questions about your dog’s diet and medical history. Then the vet may recommend intradermal skin testing and/or serologic (blood) testing to try to identify what, exactly, is triggering your dog’s allergies.

Diagnosing environmental and food allergies

Just like in people, diagnosing food and environmental allergies in dogs can be a challenge. 

When it comes to diagnosing food allergies, the best and most accurate method is to use an elimination trial. An elimination trial is when you feed your dog a hypoallergenic diet for eight to twelve weeks to test whether their symptoms improve. The diet must not contain any ingredients that the pet has eaten in the past — including treats, foods, or supplements.

In addition to elimination diets, your veterinarian may be able to perform a blood test to help determine whether your dog is allergic to specific foods. These are known as serum IgE tests.

Diagnosing environmental allergies in dogs can be performed using two techniques: RAST testing or intradermal skin testing. 

  • Intradermal skin testing: is a highly specialized and complex process, so dogs requiring such testing are almost always referred to a board-certified veterinary dermatologist. Because intradermal testing can be uncomfortable, dogs are typically sedated for this procedure and a section of their coat is shaved in order to allow the injection sites to be monitored for a reaction. It involves injecting a small amount of a pure allergen under the skin and measuring the allergic response. Intradermal testing is the gold standard when it comes to diagnosing environmental allergies.

  • RAST or serologic testing: requires drawing a single blood sample, that can be drawn by your veterinarian, to test a dog’s response to environmental allergens, so it is less invasive and does not require sedation. The blood sample is then submitted to a laboratory for analysis. However, the downside is that the results are not always as accurate as intradermal testing.

How can I treat my dog’s allergies?

You can alleviate your dog’s allergy symptoms by treating them with anti-allergy medication, preventing exposure to allergens, and treating secondary skin infections with antibiotics, antifungals, and/or ear medications.

Allergic responses like itching can be reduced with antihistamines, steroids, or other immune-modulating drugs. Your vet will prescribe the best treatment based on your particular dog’s needs and considerations. Another option? Allergy shots, just like people get! Vets can use the data from allergy testing to create a custom treatment that helps desensitize your dog’s immune system.

Preventing exposure to allergens can be a little more involved than simply giving a pill to your pup. It may mean limiting walks through woods or parks when pollen levels are high, dusting and vacuuming more thoroughly to minimize dust mites, and cleaning your dog’s bedding more often. A monthly flea preventative is the best way to eliminate fleas as an allergy vector.

Food allergies are more complicated. Identifying a food allergy and changing a dog’s diet to treat it takes time. First of all, remember that easing your dog to a new type of food needs to be done gradually to minimize gastrointestinal distress. Dogs that are allergic to chicken or beef may need to eat a novel protein, such as rabbit, venison, or turkey. It can take up to 12 weeks for symptoms to resolve themselves after changing your dog’s diet.

In general, changing your dog’s diet to try to rule out food allergies should be done only under your veterinarian’s supervision. Randomly switching your dog’s diet around can actually do more harm than good, and a true “hypoallergenic” diet can be obtained only from a veterinarian; over the counter diets that claim to be ‘hypoallergenic’ or ‘novel protein’ do not have the same quality control as veterinary prescription diets where there is absolutely no cross-contamination during the manufacturing of the diets.

Summary of the difference between food allergies and environmental allergies in dogs

Food and environmental allergies can wreak havoc on your dog’s skin and overall happiness. While symptoms of both often overlap, there is a big difference between food and environmental allergies for dogs, so it’s important to speak to your veterinarian for advice. They’ll be able to help you decide whether it’s best to try an elimination diet or to conduct testing for environmental allergies. It can take time to figure out what is triggering your dog’s allergies, and how best to treat them: what works for one dog may not work for another, so patience is key. But by being a knowledgeable advocate for your dog — and with a lot of help from your vet — you can figure out how to prevent your pup’s allergies from being a pain in the paw.

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