Dog Allergies Explained: The Most Typical Causes

Why Do Dogs Develop Allergies?

Allergies occur when a dog’s immune system reacts too strongly to a normally harmless, everyday substance. This can include certain animal or plant proteins, pollen, dust mites, flea saliva, or even specific chemicals. The body mistakenly identifies the allergen as a threat and triggers an inflammatory response.

It is important to understand that a dog’s allergy is not always caused by a single factor. In many cases, symptoms develop due to the combined effect of multiple allergens. For example, a dog with a food allergy may be sensitive to chicken while also reacting to house dust mites. Cross-reactivity can also occur, when the immune system’s response to one protein leads to sensitivity to structurally similar—but seemingly unrelated—allergens. For instance, a dog allergic to poultry may react not only to chicken but also to turkey.

Factors that can predispose dogs to allergies:

• Genetic predisposition: Certain breeds (e.g., Golden Retrievers, Labrador Retrievers, West Highland White Terriers) are more prone to developing allergies.
• Age: Environmental allergies typically appear within the first three years of life, while food allergies are more commonly diagnosed around 5–7 years of age.
• Environmental factors: Dust, pollen, mold, and chemicals.
• Diet and digestion: Poor-quality nutrition, as well as additives and artificial ingredients in dog food, may increase the risk of allergic reactions.

Itching and the resulting intense scratching are common symptoms of allergies in dogs.

What Symptoms May Indicate That Your Dog Has Allergies?

Allergy symptoms in dogs most commonly affect the skin and the digestive system. The following signs are typical:

• Constant itching and scratching: The dog compulsively and intensely scratches, rubs its skin, and chews at its paws. The itching may start mildly but can progress over time to redness, inflammation, hot spots (red, inflamed, oozing areas of skin), and hair loss.
• Hair loss and discoloration: Due to persistent scratching and chewing, hair may begin to fall out, and the skin can become discolored, with areas of hyperpigmentation developing.
• Rashes and hot spots: Red, moist lesions may appear, often on the neck, lower back, paw pads, and groin area. These so-called hot spots are frequently accompanied by secondary bacterial infections.
• Ear infections: Chronic or recurrent ear infections are often a sign of allergies. The ears may become red, and an unpleasant-smelling discharge can appear in the ear canal.
• Digestive issues: Diarrhea, increased gas production, bloating, vomiting, and abdominal discomfort can also indicate allergies, especially in cases of food allergies.
• Paw licking: Constant licking or chewing of the paws is often one of the earliest signs of skin allergies. In dogs with light-colored coats, reddish-brown discoloration may appear on the paws due to saliva staining.
• Eye and nasal discharge, sneezing: Less common, but can occur with environmental allergies, especially to pollen or mold.
• Coughing and respiratory symptoms: Although rarer in dogs, dry coughing and difficulty breathing can also be signs of an allergic reaction.

Red, moist patches (hotspots) may appear on the dog’s skin, which can easily become infected.

What Are the Main Types of Allergies in Dogs?

Allergies in dogs can originate from a variety of sources, and in many cases there is not just a single triggering factor. Below is an overview of the most common types of allergies, their characteristics, symptoms, and key points to know.

1. Food allergies

Food allergies develop when a dog’s immune system reacts excessively to a specific dietary ingredient—most commonly a type of protein. The issue often arises because dogs may consume the same ingredients for long periods, eventually leading to sensitivity.

Most common allergens:

• chicken
• beef
• dairy products
• eggs
• soy
• grains (e.g. wheat, corn, rice)

Symptoms:

• persistent itching, especially around the ears, paws, and face
• redness, inflammation, hair loss
• recurring ear infections
• digestive issues (diarrhea, vomiting, bloating)

What can you do?

One of the most effective approaches is an elimination diet, during which the dog is fed only a novel protein and carbohydrate source for 6–8 (or even 8–12) weeks.

Careful monitoring of symptoms, followed by the gradual reintroduction of ingredients, can help identify the specific allergen.

Veterinarians may also recommend feeding a special hypoallergenic diet.

Many dogs are allergic to pollen, including ragweed pollen.

2. Environmental allergies (atopic dermatitis)

Environmental allergies—also known as atopy—are reactions to allergens that are inhaled or come into contact with the skin. This is also very common and often appears seasonally, although in some cases it can persist year-round.

Common allergens:

• pollen (trees, grasses, weeds, e.g. ragweed)
• house dust mites
• mold spores
• chemicals, cleaning agents

When do symptoms appear?

• seasonally (e.g. spring–summer or early autumn during pollen season)
• year-round (e.g. in cases of dust mite sensitivity)

Typical symptoms:

• itching (especially on the paws, abdomen, and armpits)
• paw licking and chewing
• redness and skin irritation
• watery eyes, and less commonly sneezing

Tips to help relieve symptoms:

• regular vacuuming and reducing indoor dust exposure
• keeping the home and kennel mold-free
• frequent washing of bedding with hypoallergenic detergent
• using gentle, skin-soothing shampoos
• omega-3 fatty acids to support skin health
• in more severe cases, veterinary treatment or immunotherapy.

Flea saliva allergy is one of the most common allergic skin conditions in dogs.

3. Flea Allergy (Flea Allergy Dermatitis, FAD)

Flea saliva allergy is one of the most common allergic skin conditions in dogs. It is important to note that the problem is not caused by the presence of fleas themselves, but by the saliva injected into the skin during a bite. Even a single flea bite can trigger a strong allergic reaction, so a heavy infestation is not necessary.

Typical symptoms:

• intense itching and scratching
• itching around the base of the tail and lower back
• redness and skin lesions
• hair loss
• frequently developing hot spots

Important to know: Wounds caused by scratching can easily become secondarily infected with bacteria or fungi.

Prevention:

• year-round flea prevention (spot-on treatments, oral tablets, collars)
• keeping the dog’s environment clean and regularly checking and grooming the coat

4. Contact allergy (contact dermatitis)

Contact allergy occurs when a dog’s skin comes into direct contact with an irritating or allergenic substance. This usually causes localized symptoms, meaning the reaction appears where the allergen touched the skin.

Common triggers:

• cleaning agents and detergents
• plastic bedding or bowls
• synthetic fabrics
• collars and harness materials
• certain metals (e.g. nickel)

Symptoms:

• redness
• itching
• hair loss in the affected area
• minor inflammation and irritation

What can you do?

• switch to gentle, fragrance-free cleaning products
• use natural materials for bedding
• observe what regularly comes into contact with your dog’s skin
• consult a veterinarian if necessary

5. Autoimmune and rarer allergic reactions

In rarer cases, a dog’s immune system may not react to external allergens, but instead attacks its own cells. These are known as autoimmune diseases.

Typical symptoms:

• widespread skin inflammation
• sores and ulcers
• hair loss
• general lethargy

These conditions require thorough diagnostic work and targeted veterinary treatment, so a veterinarian should be consulted if there is any suspicion.

Allergies can significantly affect a dog’s overall well-being.

6. Drug allergies

Dogs can sometimes develop allergic reactions to certain medications. These reactions usually occur suddenly and can be difficult to recognize at first, as the symptoms are often similar to those of other conditions. The reaction is caused by the body’s hypersensitivity to a specific active ingredient.

Common triggers:

• antibiotics
• painkillers
• vaccinations (rarely)
• dewormers or other veterinary medications

Symptoms:

• sudden onset of itching
• redness and swelling
• hives-like skin lesions
• vomiting and diarrhea
• in severe cases, difficulty breathing (anaphylactic reaction)

Important to know:

• Symptoms often appear shortly after the medication is administered.
• If such a reaction is observed, a veterinarian should be contacted immediately.
• The specific active ingredient should be avoided in the future.

Food allergies are also becoming increasingly common in dogs and should not be confused with food intolerance.

Food allergy or food intolerance? Understanding the difference

The digestive symptoms listed above do not always mean that your dog has an allergy. In many cases, the underlying cause is a digestive disorder or food intolerance. Many owners confuse food allergy with food intolerance, even though it is important to distinguish between the two. But what exactly is the difference, and how can you recognize them in your dog?

Food intolerance

In the case of food intolerance, the dog’s body is unable to properly digest certain nutrients or ingredients in the food. Unlike allergic reactions, the immune system is not involved, and no inflammatory or immune response occurs. The problem is usually related to digestive function—for example, the dog may not produce enough enzymes to break down lactose or other components, or may be sensitive to certain additives, artificial colorings, or preservatives.

Symptoms of food intolerance:

• diarrhea
• bloating
• intestinal gas
• nausea
• vomiting
• stomach discomfort
• loss of appetite

In summary, food intolerance does not trigger an immune response and does not cause inflammation. The problem typically resolves once the offending food is removed from the diet.

Food allergy

Food allergy, on the other hand, is an overreaction of the dog’s immune system to certain proteins, such as chicken, fish, eggs, or other protein sources. In these cases, the body mistakenly identifies the ingredient as harmful and triggers inflammatory processes, leading to various—and often visible—symptoms.

Symptoms of food allergy:

• itching
• hair loss
• skin redness
• diarrhea
• ear infections

Important to know:
Because the immune system continuously reacts to the allergen, symptoms can become chronic and may affect multiple organ systems. Food allergies do not resolve on their own, which is why an accurate diagnosis and an appropriate diet that eliminates the triggering protein are essential.

Your veterinarian can help identify the allergen if there is a suspicion of allergy in your dog.

How is an allergy test performed in dogs?

Identifying the exact cause of allergies in dogs is not always straightforward, as symptoms can be triggered by many different factors and often appear in very similar ways. For this reason, allergy testing is usually a multi-step process aimed at narrowing down possible causes and identifying the specific allergen.

The first step is always a thorough veterinary examination, during which the veterinarian asks the owner about the dog’s symptoms, diet, lifestyle, and when the issues first appeared. This information alone can already provide important clues about the direction of further testing.

After this, a so-called exclusion (elimination) diagnosis is often carried out. During this phase, the veterinarian first rules out other conditions that can cause similar symptoms, such as:

• flea infestations or other parasites
• bacterial or fungal skin infections
• hormonal or metabolic diseases

If these are not confirmed, targeted allergy tests may follow.

In cases of suspected food allergy, the most reliable method is an elimination diet. During this process, the dog is fed only a novel protein source it has never consumed before for several weeks (usually 6–8 weeks). If symptoms improve and then reappear after reintroducing a specific ingredient, this helps identify the allergen.

For environmental allergies, different tests may also be used:

• blood tests, which can indicate sensitivity to multiple allergens
• skin testing (intradermal testing), where small amounts of allergens are injected into the skin and reactions are observed

It is important to know that these tests do not always provide clear-cut answers, so results must always be interpreted alongside clinical symptoms.

Allergy testing is therefore not a single quick test, but a complex, time-consuming process. However, an accurate diagnosis is essential, as it is the only way to effectively manage a dog’s allergy in the long term and prevent recurring symptoms.

How is allergies treated in dogs?

The treatment of allergies in dogs always depends on what is triggering the symptoms. Since there is often more than one underlying cause, treatment typically involves several steps and requires long-term management. The main goal is not only to relieve symptoms but also to identify and, if possible, eliminate the underlying cause.

1. Identifying and avoiding the allergen

The most effective solution is always to determine what is causing the allergy and keep the dog away from that substance.

• This may include:
• dietary changes in case of food allergies
• flea control in flea allergy dermatitis
• reducing environmental allergens (dust, pollen, chemicals)

However, complete avoidance is not always possible—for example in the case of pollen or dust mites.

2. Special diet and nutrition

In food allergies, diet plays a key role in managing symptoms.

Possible approaches include:

• hypoallergenic diets
• novel protein sources (e.g. lamb, rabbit, fish)
• additive-free nutrition

The elimination diet is not only a diagnostic tool but also a therapeutic one, as it often leads to significant improvement on its own.

3. Medication

For more severe or persistent symptoms, a veterinarian may recommend medication.

Commonly used treatments include:

• antihistamines (to reduce itching)
• anti-inflammatory drugs (e.g. steroids)
• immunomodulatory medications

Important: these should only be used under veterinary supervision, as improper use may cause side effects.

4. Skin care and topical treatment

Since allergies often affect the skin, proper skin care is essential.

Helpful measures include:

• regular bathing with soothing, medicated shampoos
• removing allergens from the coat (e.g. pollen)
• moisturizing and skin-protective products

This is especially useful in cases of environmental allergies.

5. Environmental management

Keeping the dog’s environment clean can significantly reduce allergic symptoms.

It is worth focusing on:

• frequent vacuuming
• regular washing of bedding
• using fragrance-free, gentle cleaning products
• reducing dust mites and mold

These may seem like small steps, but they can make a big difference over time.

6. Immunotherapy (desensitization)

In some cases, a veterinarian may recommend allergen-specific immunotherapy.

This means the dog is gradually exposed to small amounts of the allergen so the immune system can “learn” to tolerate it and react less strongly over time.

Important notes:

• it is a long-term treatment (months or even years)
• it is not effective in every case
• but it can provide lasting improvement

7. Supportive care

Certain natural compounds and dietary supplements may also help reduce symptoms and support the immune system.

Common supplements include:

• omega-3 fatty acids (anti-inflammatory effect)
• probiotics for gut health
• vitamins and trace elements supporting skin and coat (e.g. zinc)
• herbal supplements that reduce itching

Allergy management is therefore not about a single “miracle solution,” but a well-structured, multi-step process. Success depends on identifying the trigger, consistent treatment, and the owner’s careful attention.

With proper care, allergic dogs can experience a significant reduction in symptoms and enjoy a more comfortable, balanced life again.

A common sign of allergies is irritated, inflamed skin, which as a dog owner it is important to pay attention to.

What can you do as a dog owner?

Keep an allergy diary! Note down:

• When do the symptoms appear?
• What food has the dog eaten?
• In what environment has the dog been?

Observe your dog carefully:

• Check the skin and coat daily
• Pay attention to the paws, ears, and groin area
• Record the severity and frequency of symptoms

Natural supportive care:

• Allergy-removing bathing: helps remove pollen, dust, and flea saliva using a pH-neutral, skin
• soothing dog shampoo
• Use skin-soothing products based on aloe vera or chamomile
• Use an Elizabethan collar (protective cone) to prevent self-inflicted injuries from scratching
• Consider herbal supplements that may help reduce itching and inflammation

Facts and myths about dog allergies

Myth 1: “The dog will outgrow allergies.”
Reality: Allergies are usually chronic, but symptoms can be managed and reduced.

Myth 2: “Only chicken causes food allergies.”
Reality: No—other proteins and ingredients can also trigger reactions.

Myth 3: “Antihistamines will solve everything.”
Reality: They may relieve symptoms, but they do not eliminate the underlying cause.

Myth 4: “A dog is only allergic if it sneezes.”
Reality: Most symptoms actually appear on the skin and in the digestive system.

Scratching can also have other causes besides allergies. Learn more about what might be behind excessive scratching in dogs.

This article is for informational purposes only and does not replace veterinary examination or treatment. For an accurate diagnosis and appropriate therapy, always consult your veterinarian.