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

Watching your beloved dog scratching itself constantly, the skin turning red, even broken and losing hair, as an owner, you must feel distressed and anxious.Dog's skin is red and itchy" is very common in pet hospitalsPet skin problems. Many owners' first reaction is: "Is my dog allergic?" 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's important to understand other possibilities. This article will help you sort out the common causes of itchy skin in dogs, focusing onDog allergy symptoms(includingDog food allergiesand environmental allergies), and explainsHow do veterinarians test for allergiesas well as commonDog allergy testingmethod.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 thought to investigate, first excluding some relatively common or easy-to-treat problems:

1. External parasite infection

  • Fleas:This is one of the most common causes. Flea bites themselves can make dogs itchy. More troublesome is that many dogs are allergic to flea saliva (called flea allergy dermatitis, FAD). Even if there are only one or two fleas on their body, it may trigger severe itching throughout the body, especially on the lower back and the base of the tail.
  • Mites:Different types of mites can cause different skin diseases. For example, scabies mites can cause severe itching and dandruff, especially on the edges of the ears, elbows, and abdomen; while Demodex mites usually cause hair loss and erythema in dogs with weakened 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 fur, possibly combing it with a fine-toothed comb, or scraping a small 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 "original culprit" but are 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 the toes, groin), leading to oily skin, redness, thickening, special odor, and itching. Dermatophytes (commonly known as "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 and 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 may 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 irritating reactions to direct contact with certain substances in the environment, such as certain plants, carpet cleaners, shower gels, etc.

Focus on allergies: Common dog allergy symptoms and types

Allergies are one of the main causes of chronic and recurrent itchy skin in dogs. After 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.
  • Redness and rash on the skin:Especially in areas with less hair, such as the abdomen, inner thighs, and armpits, you can see redness of the skin, or even small red spots or rashes.
  • Recurrent ear infections (otitis externa):The ear canal is red, swollen, has secretions, and has an odor. 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 inflammation, the skin will gradually become rough, thickened (lichenification), the color will darken, 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 (in a small number of cases):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. Dogs have an allergic reaction to certain substances in the environment, such aspollen (from trees, grass, weeds), dust mites (hidden in the home environment), mold spores, certain plants, insectsetc. This allergy usually has a certainseasonal nature(for example, symptoms worsen in a certain season), but if the allergens are present all year round (such as dust mites), the symptoms may persist throughout the year.
  • Food Allergies:Dogs have an allergic reaction to certain ingredients in food (usuallyprotein). Common food allergens includebeef, chicken, dairy products, eggs, soy, wheat, cornetc. Symptoms caused by food allergies are usuallynon-seasonaland can occur all year round, and may be accompanied by digestive symptoms.
  • Flea Allergy Dermatitis (FAD):Allergic reaction to the saliva injected during flea bites. This is a common cause of severe itching in dogs, 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 problems are caused by allergies, they will recommend appropriate testing methods based on the specific situation to try to find out the allergens.But please understand that there is currently no allergy test that is 100% perfect. All test results need to be professionally interpreted by a 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 excludingDog food allergies. The process is relatively long and requires great patience and strict implementation from the owner:

  1. Strictly restrict diet:Under the guidance of a veterinarian, choose a food with a novel protein and carbohydrate source that the dog has never eaten before (usuallyveterinary prescription hydrolyzed protein foodorlimited single protein food, or, in special cases, homemade single-ingredient food), andonly feed this one food.
  2. Continue for a sufficient period of time:This strict restricted diet needs to be maintained for at least8 to 12 weeks.
  3. Eliminate all other foods:During this period,absolutely notGive the dog any other snacks, jerky, chews, dental bones, fruits, vegetables, or even let it lick food scraps that fall on the ground, and do not feed medications containing palatants (need to confirm with the veterinarian).
  4. Observe changes in symptoms:If the dog's itching symptoms are significantly improved after strictly implementing the elimination diet (usually starting to appear in 4-8 weeks), then food allergies are highly suspected.
  5. Provocation test (optional but recommended):In order to finally confirm and find out 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 symptoms recur after adding a certain ingredient, then this ingredient is likely to be an allergen.

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

This test is mainly used to help diagnoseenvironmental allergies(atopic dermatitis) and 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 operating requirements, requires discontinuation of 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 the dog's blood 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, this test'sresults require very careful interpretation:

  • Positive does not equal clinical allergy:Detecting a positive IgE antibody only indicates 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 is necessary to combine the dog's actual exposure history and symptom manifestations to judge.
  • Food allergen results are highly controversial:There is currently a lot of controversy about the accuracy of blood tests in diagnosing food allergies. The results can usually only be used as a reference for selecting an elimination diet, andcannot 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 formulating avoidance measures or selecting desensitization treatment plans, especially when the dog is not suitable for intradermal testing.

Tashikin also providesCanine IgE Allergy Test Kits, which is a tool for veterinarians to use to help them quickly assess a dog's total IgE levels or IgE levels against specific allergens 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 test results, and recommend the most appropriateDog allergy testingmethod.

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

Having understood so many possible causes and testing methods, I believe you can better appreciate why we have always emphasized -The first step, and the most important step, in dealing with dog skin problems is always to seek the help of a professional veterinarian!Do not handle it yourself just because you think it's "just a minor problem" or "what medicine is said to be effective online." Incorrect diagnosis and medication may not only delay treatment and make the dog suffer in vain, but may even mask more serious underlying diseases, or cause 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,Look for clues of parasites, infections, or other abnormalities.
  2. Carry out necessary examinations,Such as skin scrapings, hair plucking microscopy, cytological smears, fungal cultures, etc. to exclude or confirm infections and parasites.
  3. Understand the medical history and living habits in detail,Assess the possibility of allergies.
  4. Recommend appropriate allergy diagnostic steps according to 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 diet management, environmental control advice, or long-term desensitization treatment.