If you're trying to figure out what's causing your dog's itchy skin, you're not alone!

One of the most common issues pet owners ask about is what's causing their dog's itching and what they can do about it. So, welcome to the Allergies Channel on Dogly, where you'll learn about itching, scratching, and other “allergic” symptoms and what you can do to keep your dogs well!

We'll be talking about answers for everything from food "allergies" to seasonal allergies, flea bites, yeast infections, and everything in between that can give your dogs itchy skin and allergic symptoms. So many problems resemble allergies that for most dogs, an accurate diagnosis takes a deep, holistic look for the root cause.

Let's dive into strategic ways to determine the underlying cause of your dog's itch, treatment options, and home-care to give your dog some scratching relief!

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7 common questions and answers on understanding allergies...

Q1: What is an allergy exactly?

An allergy is a state of over-reactivity or hypersensitivity of the immune system to a particular substance called an allergen. When a dog is exposed to it, he/she develops various physical symptoms. Commonly you'll notice itchy skin but it can also be itchy eyes and ears, sneezing and coughing, or even vomiting and diarrhea.

The big allergens are environment allergies and food allergies (which are often actually sensitivities rather than allergies…but more on that later.)

Q2: How do you know what type of “allergies” your dog is suffering from, or if it's even an allergy at all?

True allergies are the result of a body having a hypersensitivity to an everyday substance—whether that’s a type of food or an environmental element such as pollen or mold.  

Your dog’s immune system identifies the allergen as something “bad” that needs to be eradicated. It then releases histamines and other chemical substances to try and eradicate the allergen, which leads to allergic reactions that can present in many ways. Often, food sensitivities and environmental allergies produce similar symptoms, making it difficult to know what the allergen is.

The main “allergy” symptoms in dogs are...

• Persistent itching/excessive scratching
• Biting/Excessive grooming and licking (paws, hindquarters)
• Skin irritations - inflamed skin or hyperpigmentation
• Lesions on paws/hot spots
• Repeated ear infections 
• Secondary skin infections
• Shedding 
• Tear stains

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Q3: Can a dog suffer from both food AND environmental allergies?

Sadly, the answer is yes. As Dr. Joseph Bartges, a veterinary nutritionist at the University of Tennessee’s College of Veterinary Medicine says: “Seasonal/environmental and food allergies do overlap, and approximately 30 percent of pets with food-responsive issues also have seasonal allergies or allergies to fleas.”

Q4: What is a food allergy exactly?

When a dog’s immune system incorrectly identifies a protein from food as harmful and launches an immune response, that's a food allergy. Hypersensitivity can develop to almost any protein or carbohydrate component of food.

Ear and skin infections can occur along with the sensation of itchy skin and the need to scratch. Some dogs will experience vomiting or diarrhea. You may be surprised to hear that true food allergies are actually quite uncommon. Often the most common causes, about 90% of the time, are food SENSITIVITIES or intolerances. Food intolerances include a wide array of reactions to food.

What does that actually mean? 

The difference between a food allergy and sensitivity is really the body’s response. With a true food allergy, the immune system initiates the reaction, while with food sensitivities or intolerances, it is the digestive system that reacts.

According to Tufts University’s School of Veterinary Medicine, chances are your dog doesn’t have a food allergy: “Suspected food allergy is a common reason people come to our nutrition clinic. They’ve often tried multiple diets. But if they all have different ingredients and the dog is not any better, it’s probably not a food allergy. Of dog owners who think their dogs may have a food allergy, only 10 percent or less actually do.” Food sensitivities though can be quite common, especially if a dog’s diet consists of lower nutrition-quality, highly processed pet food.

Okay, but tell me more...

Another common cause is feeding the same food every day for long periods, often developing a sensitivity to the protein source (chicken, for example), although grains and vegetables can also be culprits.

What to watch for with your dog

If your dog's body is reacting with GI symptoms/digestive issues from food such as diarrhea or vomiting, the underlying cause is more likely to be:

• food intolerance or sensitivity
• a diet that is too rich in fats for your dog
• improper food handling/bacteria issues
• the percentage of fiber in the food

 The common signs of true food allergies are:

• lesions
• recurrent ear infections
• itchiness
• scabs
• hot spots
• vomiting*
• diarrhea*

*Unlike food allergies, with environmental allergies you most often will NOT see GI distress.

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Q5: What are environmental allergies and how do they differ from food allergies? 

Environmental Allergies (inhalant allergies) are mainly tree pollens (cedar, ash, oak, etc.), grass pollens, weed pollens (ragweed), mold spores, mildew, and house dust mites. Many of these allergies occur seasonally, such as ragweed, cedar, and grass pollens. Others such as molds, mildew, and house dust mites happen year round.

What to watch for with your dog

Dogs with environmental allergies can present with these symptoms too, but they tend to show more skin-related symptoms:

• Itchy skin (pruritus)
• Inflamed skin
• Hyperpigmentation (a darkening and thickening of your dog's skin)
• Rubbing the face
• Biting & licking the paws (often causing raw lesions)
• Scratching, particularly in the underarms area
• Recurrent ear infections 
• Secondary skin infections
• Shedding, hair loss
• Tear stains

Dogs' symptoms tend to look more like skin allergies because dogs tend to absorb seasonal allergens through their paws.

Dog ages for allergies

Another fact about environmental allergies: they mostly occur in dogs over at least 1 year of age. Older dogs have had more exposure to an allergen, making them more sensitized. On the flip-side, food allergies can develop at any age.

Typically, the immune system overreacts to environmental allergens. So if your dog exhibits symptoms of an allergic reaction, like severe itching and your dog's itching persists, it’s probably a seasonal allergy. Later in the Allergies Channel, we'll talk about some effective, natural ways to alleviate seasonal allergies.

More tips to help you get to the cause of your pet's condition

Another way you can tell if you're dealing with food or environmental allergies is that a food allergy typically does not respond well to corticosteroids or other medical treatment. If you've been treating your dog with these therapies for environmental allergies and they aren't working, you may have a food allergy on your hands.

Q6. Do the foods we give our dogs impact any environmental allergies they may have?

Actually, yes, certain foods can indirectly exacerbate an environmental allergy.

Give me an example

My dog Carli had allergic symptoms of fur loss, itching in the armpit area, and hyperpigmentation. Symptoms started at the onset of prime spring seasonal allergies. Naturally, my first inclination was “it’s environmental allergies.” I wasn’t wrong, BUT…because her immune system was already reacting to the environmental allergies, when I fed her certain foods that are high in histamines, her system went into mega overload. It was as if the environmental allergies brought a light rain shower, and the high-histamine foods on top of that triggered a downpour. If I were to feed her those same foods OUTSIDE her allergy season, she likely would not react the same way.

Nutrition always plays a part in allergies, whether to strengthen your dog's immune system to minimize them or make your dog more vulnerable to them. And that's something you can control simply with your dog's food every day!

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Q7. What about contact allergies and how do they affect your dog's skin and beyond?

They're the least common type of allergy -- resulting from direct contact to allergens and usually showing localized reactions on your dog's skin at the site of contact (in addition to other manifestations).

Give me an example

Contact allergies come from irritants such as pyrethrins found in flea collars, pesticides used on lawns, grasses, materials such as wool or synthetics used in carpets or bedding, etc.

What to watch for in your dog

Contact allergies can develop at any age. The localized skin problems you can expect make it easier to track back to the cause -- such as on the neck if due to a chemical flea collar or on the belly from allergens in your dog's bedding. They usually appear as inflamed, sometimes bumpy skin, that is also…you guessed it….ITCHY.

(Take a look at my guide on “going green” to eliminate common contact allergens from your pet’s environment.)

Next up in the Allergies Channel on Dogly

Now that you've figured out all the reasons for your dog itching, continue learning how to help your itchy dog in the next step-by-step guide on misdiagnosed allergies in dogs.

Or hop over to the Allergies Channel if you'd like to ask a question in the Community discussion or start any of the other step-by-step guides in Seasonal Allergies, Environmental Allergies, and Food Allergies.

And if you ever need more personalized wellness help, please reach out!

Additional sources:

Vetericyn

Merck

ACVD