Is your dog's skin always red and constantly scratching? Don't take it lightly! Understand the possible causes and allergy testing (veterinary diagnosis is the most critical!)

It's heartbreaking and worrying for owners to watch their beloved dogs constantly scratching themselves, their skin turning red, even breaking and losing hair. "**Dog skin redness and itching**" is a very common **pet skin problem** in pet hospitals. Many owners' first reaction is: "Does my dog have allergies?" Indeed, allergies are one of the main causes of long-term itching in dogs, but it is by no means the only cause! Before rushing to change your dog's food or looking for "anti-allergy" methods, it is important to understand other possibilities. This article will help you sort out the common causes of itchy skin in dogs, focusing on **dog allergy symptoms** (including **dog food allergies** and environmental allergies), and explaining **how veterinarians test for allergies** and common **dog allergy tests**. **But please remember that this article cannot replace the professional judgment of a veterinarian! Only a veterinarian can find the real cause and give the correct treatment plan.**

Not just allergies! Possible causes of red and itchy skin in dogs

When a dog has itchy skin, veterinarians usually act like detectives, following a certain line of thinking to rule out some relatively common or easily treated problems:

1. External parasite infection

  • **Fleas:** This is one of the most common causes. Flea bites themselves can make dogs itchy, and more troublesome, many dogs are allergic to flea saliva (called flea allergy dermatitis, FAD), even if there are only one or two fleas on the body, it may cause severe itching throughout the body, especially in the lower back and base of the tail.
  • **Mites:** Different types of mites can cause different skin diseases. For example, scabies mites cause severe itching and dandruff, especially on the ear margins, elbows, and abdomen; while Demodex mites usually cause hair loss and erythema in dogs with low immunity, with varying degrees of itching.
  • **Lice:** Although relatively rare, dogs can also be infected with lice, causing itching and restlessness.
  • **How veterinarians check:** Veterinarians will carefully examine the dog's coat, possibly combing it with a fine-toothed comb, or scraping a little skin sample and observing it under a microscope to look for insects or eggs.

2. Skin infection

  • **Bacterial infection (pyoderma):** Skin redness, small pustules, papules, scabs, hair loss, odor, etc. Bacterial infections are often not the "culprit", but secondary to other problems, such as impaired skin barrier (allergies, endocrine problems), damp skin folds, trauma, etc.
  • **Fungal/yeast infection:** The most common is Malassezia infection, which often occurs in warm and humid areas (ears, armpits, between toes, groin), leading to oily, red, thickened skin with a special odor and itching. Ringworm (usually called "dog ringworm") can also cause hair loss, dandruff, and itching.
  • **How veterinarians check:** Veterinarians may use tape to stick to the skin surface, or take a sample with a cotton swab and observe it under a microscope to see if there are a large number of bacteria or yeast. For suspected ringworm, a Wood's lamp examination or fungal culture may be required.

3. Allergies

If parasites and infections are ruled out (or these problems always recur), then allergies are a very important suspect. We will discuss this in detail in the next section.

4. Other possible causes

  • **Endocrine diseases:** Such as hypothyroidism, hyperadrenocorticism (Cushing's syndrome), these endocrine disorders may lead to thinning of the skin, hair loss, susceptibility to infection, pigmentation, etc., sometimes accompanied by itching.
  • **Autoimmune diseases:** Relatively rare, it is the dog's own immune system attacking skin tissue, which can lead to severe skin ulcers, scabs, etc.
  • **Nutritional problems:** Lack of certain essential fatty acids, vitamins, or minerals may also affect skin health.
  • **Contact dermatitis:** Allergic or irritant reactions to direct contact with certain substances in the environment, such as certain plants, carpet cleaners, bath products, etc.

Focus on allergies: Common dog allergy symptoms and types

Allergies are one of the main causes of chronic, recurrent skin itching in dogs. When a veterinarian rules out parasites and infections, they will usually focus on the possibility of allergies.

CommonDog allergy symptomsMay include:

  • **Itching (Pruritus):** This is the most core and typical symptom of allergies! Dogs may constantly scratch, bite, rub their bodies, or repeatedly lick a certain part, common itchy areas include: **paws (constantly licking toes), abdomen, armpits, groin, ears (repeatedly scratching ears, shaking head), face (rubbing face) and around the anus**.
  • **Red skin, rash:** Especially in areas with less hair, such as the abdomen, inner thighs, armpits, etc., you can see red skin, and even small red dots or rashes.
  • **Recurrent ear infections (otitis externa):** The ear canal is red, swollen, with secretions, odor, and the dog frequently shakes its head and scratches its ears. This is a very common manifestation of allergies, especially food allergies.
  • **Hair loss, thickened skin, pigmentation:** Due to long-term, chronic itching and inflammatory stimulation, the skin will gradually become rough, thickened (lichenification), darker in color, and the hair will become sparse or even fall out.
  • **Skin odor:** Secondary bacterial or Malassezia infections often cause the skin to emit an unpleasant odor.
  • **Gastrointestinal symptoms (a small number):** Some dogs with food allergies may also have digestive problems such as vomiting, diarrhea, or increased bowel movements in addition to skin symptoms.

Main types of dog allergies

  • **Environmental allergies (Atopic Dermatitis):** This is the most common type, where dogs have an allergic reaction to certain substances in the environment, such as **pollen (from trees, grass, weeds), dust mites (hidden in the home environment), mold spores, certain plants, insects**, etc. This type of allergy usually has a certain **seasonality** (for example, symptoms worsen in a certain season), but if the allergen is present all year round (such as dust mites), symptoms may persist throughout the year.
  • **Food Allergies:** Dogs have an allergic reaction to certain ingredients in food (usually **protein**). Common food allergens include **beef, chicken, dairy products, eggs, soy, wheat, corn**, etc. Symptoms caused by food allergies are usually **non-seasonal**, may occur all year round, and may be accompanied by digestive symptoms.
  • **Flea Allergy Dermatitis (Flea Allergy Dermatitis, FAD):** An allergic reaction to the saliva injected during flea bites. This is a common cause of severe itching in dogs, and even occasional flea bites can trigger it.

How do veterinarians test for allergies? (How Vets Test for Allergies)

If your veterinarian suspects that your dog's skin problem is caused by allergies, they will recommend appropriate testing methods to try to identify the allergens based on the specific situation. **But please understand that there is currently no allergy test that is 100% perfect, and all test results need to be professionally interpreted by the veterinarian in conjunction with the dog's medical history and clinical symptoms.**

1. Elimination Diet Trial - The gold standard for diagnosing food allergies

This is currently the most reliable method for diagnosing or excluding **dog food allergies**. The process is relatively long and requires great patience and strict execution from the owner:

  1. **Strictly restrict diet:** Under the guidance of a veterinarian, choose a food source that the dog has never eaten before, with a novel protein and carbohydrate source (usually **veterinary prescription hydrolyzed protein food** or **restricted single protein food**, or in special cases, homemade single-ingredient food), and **only feed this one food**.
  2. **Continue for a sufficient time:** This strict restricted diet needs to be continued for at least **8 to 12 weeks**.
  3. **Eliminate all other foods:** During this period, **absolutely do not** give the dog any other snacks, jerky, chews, dental bones, fruits, vegetables, or even lick food scraps that fall on the ground, and do not feed drugs containing palatability enhancers (need to confirm with the veterinarian).
  4. **Observe symptom changes:** If the dog's itching symptoms improve significantly after strictly following the elimination diet (usually starting to appear in 4-8 weeks), then food allergies are highly suspected.
  5. **Challenge test (optional but recommended):** To finally confirm and identify the specific allergenic food, the veterinarian may recommend adding back one of the food ingredients that the dog used to eat every 1-2 weeks after the symptoms improve, and observe whether the symptoms recur. If the symptoms recur after adding a certain ingredient, then this ingredient is likely to be the allergen.

2. Intradermal Allergy Testing (IDT) - mainly used for environmental allergies

This test is mainly used to help diagnose **environmental allergies** (atopic dermatitis) and to select allergens for subsequent desensitization treatment. The veterinarian (usually a veterinary dermatologist) will inject a small amount of various environmental allergen extracts (such as various pollens, dust mites, molds, etc.) into the shaved skin of the dog under sedation or anesthesia, and then observe whether there is a red and swollen reaction (wheal) at each injection site. The advantage of this method is that it is relatively intuitive, but it requires high operational requirements, requires stopping certain drugs, and has little diagnostic value for food allergies.

3. Serum Allergy Testing - Blood test

This method only requires drawing a small amount of blood from the dog and sending it to a professional laboratory to test the level of IgE antibodies in the blood against specific allergens (including environmental allergens and some food allergens). Its advantages are that it is simple and convenient to operate, has little stress on the dog, and is usually not affected by short-term drug use. However, the **interpretation of the results of this test needs to be very cautious**:

  • **Positive does not mean clinical allergy:** Detecting a positive IgE antibody only means that the dog is "sensitized" to the substance, but it does not necessarily mean that this substance is the cause of the current clinical symptoms. It needs to be judged in conjunction with the dog's actual exposure history and symptom presentation.
  • **Food allergen results are controversial:** There is currently a lot of controversy about the accuracy of blood tests for diagnosing food allergies, and the results can usually only be used as a reference for selecting an elimination diet, and **cannot replace the food elimination trial**.
  • **Environmental allergen results are valuable for reference:** For environmental allergies, the results of blood tests can be used as a reference for developing avoidance measures or selecting a desensitization treatment plan, especially when the dog is not suitable for intradermal testing.

Tashikin also providesCanine IgE Allergy Test Strips (C.NT-proBNP IgE Test Kits), which is a tool for veterinarians to quickly assess total IgE levels or IgE status against specific allergens in dogs as part of a comprehensive diagnosis.Learn more about Tashikin diagnostic products

**Ultimately, your veterinarian will comprehensively judge the most likely cause based on the dog's specific medical history, symptoms, living environment, and various examination results, and recommend the most appropriate **dog allergy test** method.**

Red and itchy skin? The first step is always to see a veterinarian!

After understanding so many possible causes and testing methods, I believe you can better appreciate why we have been emphasizing that - **to deal with dog skin problems, the first step, and the most important step, is always to seek the help of a professional veterinarian!** Do not deal with it yourself because you think it is "just a small problem" or "what medicine is effective online". Incorrect diagnosis and medication may not only delay treatment and make the dog suffer in vain, but may even cover up more serious underlying diseases, or bring new problems due to drug side effects.

**Please take your dog to the veterinarian immediately, they will help you through a professional process:**

  1. **Carefully examine the skin condition** for signs of parasites, infections, or other abnormalities.
  2. **Conduct necessary examinations,** such as skin scrapings, hair plucking microscopy, cytology smears, fungal cultures, etc., to rule out or confirm infections and parasites.
  3. **Understand the medical history and lifestyle in detail** to assess the possibility of allergies.
  4. **Recommend appropriate allergy diagnostic steps based on the situation,** such as starting a food elimination trial or performing allergen testing.
  5. **Finally, develop a targeted, individualized treatment plan,** which may include drug treatment (such as drugs to control itching, antibiotics, antifungals), specially formulated medicated shampoos, strict dietary management, environmental control recommendations, or long-term desensitization treatment.