Atopy (Allergies) in Dogs

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Overview of Dogs with Allergies

Atopy is a pruritic (itchy) skin disease of dogs that is caused by an allergy to substances in the environment that are contacted through the air, either by absorption through the respiratory tract or contact through the skin. Atopy is thought to be an inherited disease. It is the second most common allergic skin condition in dogs; only flea allergy dermatitis is more common.

Symptoms of atopy usually begin relatively early in life, often by one year of age. Symptoms usually are seasonal at first, with most dogs showing clinical signs in the summer months when airborne allergens (such as plant pollens) are present in higher concentrations. As atopic dogs age, their symptoms tend to become less seasonal as they become allergic to more substances. Eventually, their itchiness can occur year-round.

Dogs with atopy are usually itchy, particularly the hands and feet. The skin may be red and irritated due to scratching, and the ears may also be inflamed. The symptoms of food allergy are difficult to distinguish from those of atopy.

What to Watch For

  • Chewing at the paws
  • Scratching the muzzle or rubbing it on the ground or with the paws
  • Scratching the ears
  • Shaking the head
  • Diagnosis of Canine Atopy

    Diagnostic tests are necessary to rule out other skin diseases, as well as to support the diagnosis of atopy. These tests may include:

  • A complete medical history and perform a thorough physical examination, especially checking the ears and the skin of the face and paws. Often, abnormalities may not be detected on the physical examination of dogs with atopy. Occasionally, redness between the toes or around the muzzle of the face is the only finding.
  • Skin scrapings to eliminate other diagnoses such as demodectic or sarcoptic mange (caused by mites).
  • Fungal culture to rule out ringworm (also called dermatophytosis).
  • Skin testing (or occasionally blood testing) to determine specific allergens to which your dog may be allergic.
  • Treatment of Canine Atopy

    Initial treatments may alleviate symptoms, but do not treat the underlying cause of the allergy. Immunotherapy (allergy shots that work by modifying your dog’s immune response to allergens) is considered the best treatment for moderate to severe or long-standing cases of atopy.

    Your veterinarian may recommend the following for your dogs:

  • Antihistamines
  • Fatty acid supplements
  • Antibiotics to treat secondary bacterial infection of the skin (called pyoderma)
  • Soothing shampoos
  • Corticosteroids (cortisone-like drugs such as prednisone) are very effective at reducing the symptoms of atopy, but they have many potential side effects that limit their long-term use. Corticosteroids should be used cautiously in the treatment of dogs with atopy.
  • Cyclosporine (Atopica®, Cyclosporine capsules, USP)
  • Home Care

    Atopy cannot be cured and most dogs require some form of therapy throughout their lives. You will need to administer any medications prescribed by your veterinarian and avoid offending allergens as much as possible. Skin testing (also called allergy testing) can be performed to identify the specific substances to which your dog is allergic. As time goes by, however, most dogs with atopy become allergic to more and more allergens, making avoidance impractical in the long run.

    You should practice strict flea control. Other itchy (pruritic) skin diseases such as flea allergy dermatitis may have an additive effect on your dog’s skin condition.

    Observe your dog for rashes and worsening of any skin lesions. Secondary bacterial infection of the skin (pyoderma) is common in dogs with atopy and can contribute to their discomfort.

    Preventive Care

    Atopy probably is an inherited disorder in dogs. Since enviromental exposure to allergens is important in the development of disease, it cannot be prevented. Airborne allergens, such as plant pollens, are difficult to avoid, and there is little that can be done to prevent the development of atopy in a predisposed individual. Dogs that grow up in low allergen environments (dry climate with high elevation) may be less likely to develop symptoms.

    Managing atopy in your dog takes some patience. However, by combining different methods of therapy, paying attention to your dog’s environment as well as you can, and observing your pet so that you can begin treatment as early as possible, you can make your pet feel his best.

    Information In-Depth on Atopy in Dogs

    Many skin diseases of dogs feature pruritus (itching) as a symptom and may appear similar to atopy. Ruling out other causes of pruritus is an important part of establishing a diagnosis.

    Diseases that can appear similar to atopy include:

  • Food allergy in dogs commonly causes a pruritic skin condition. As with atopy, dogs with food allergy often chew their feet, rub their faces and scratch their ears. Thus, the symptoms of food allergy are virtually indistinguishable from those of atopy. One important historical difference to remember is that atopy symptoms usually begin between one and four years of age, whereas food allergy can begin at any age. A dog with an onset of signs that is less than eight months of age or over six years of age, is unlikely to have atopy. Also, atopy is usually well controlled by treatment with corticosteroids (hormones) like prednisone. Food allergy is variably responsive to prednisone; only about 50 percent of affected dogs will respond.
  • Flea allergy dermatitis is the most common allergic skin disease seen in the United States. Like food allergy, it is variably responsive to corticosteroids. Dogs with flea allergy tend to chew and scratch at their back ends, so lesions are typically seen over the rump, on the belly and between the hind legs. This difference helps to differentiate this disease from atopy. It is possible, however, to see atopy and flea allergy in the same animal.
  • Scabies is an itchy skin disease of dogs caused by the sarcoptic mange mite. Affected dogs are extremely itchy and often have lesions on their ears, elbows and hocks. Lesions may also be seen elsewhere on the dog. This disease is poorly responsive to treatment with corticosteroids.
  • Pyoderma (bacterial infection of the skin) is often associated with atopy and other pruritic skin diseases. Chronic self-trauma to the skin breaks down normal defense mechanisms and allows colonization by bacteria leading to infection. Infected skin can be very itchy. Some animals with atopy are only mildly itchy most of the time but may be much worse when they have pyoderma. Less commonly, yeast infections of the skin may be seen secondary to atopy and can also cause the animal to be itchy.
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