Guide to Dealing with Your Dog’s Allergies

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Overview of Dealing with Dog Allergies

One of the most difficult conditions that dog owners have to deal with, are allergies and the problems that they cause in their dogs. In the spring and early summer, the calls start rolling in: “Doc, help me with my dog’s skin allergies!”

Allergies are one of the MOST frustrating problems for both the owners and the veterinarian. Owners often need to pursue several treatments before finding an effective one and can feel as though nothing really works for their dog. The treatments’ effects are temporary, the symptoms come back, or the treatment that works has substantial side effects. On the veterinarian’s side, the treatment options for skin allergies are rarely if ever ideal, and no single product works consistently and permanently for all dogs and allergies.

What are Dog Allergies?

Dog allergies are common, and they can present a chronic lifelong condition that pets and owners struggle with throughout their lives. Allergies are also not confined to a single specific problem. “Allergies” are a very general term to describe a group of skin allergies that may be caused by a multitude of factors in dogs. The medical terms commonly used by veterinarians include allergic dermatitis and cause-related terms including flea bite allergy, food allergy, and atopy.

Allergies are immune reactions to a given substance (allergen) that the body recognizes as foreign. These reactions occur following an initial exposure to the allergen, often coupled with the subsequent development of a hypersensitivity that causes itching and inflammation upon future exposures.

What are Most Common Dog Allergies?

The most common classes of allergic dermatitis seen in dogs include flea bite allergies, food allergies, and atopy. This last class is an allergic condition caused by inhaled allergens or the absorption of allergens through the skin. It is common for some dogs to have multiple allergies; they can be allergic to chicken but also to grass pollens, molds, tree pollens, and fleas. Many dogs develop multiple allergies to many different things, which can further complicate the treatment process.

What are Signs of Allergies in Dogs?

The first symptoms that owners typically see in allergic dogs are most related to skin allergies. They include scratching, licking, and chewing or biting the skin, feet, and ears.

Other signs of signs of allergies in dogs include:

  • red, raised, scaly areas on the skin
  • chewing at the paws
  • scratching the muzzle and rubbing it on the ground or with the paws
  • shaking the head
  • bumps, crusts, or pus-filled vesicles on the skin
  • increased skin pigmentation
  • thickened skin
  • loss of hair
  • brownish stains around the home (caused by salivary staining)
  • scratching the ears
  • head shaking (suggesting an ear infection)

What are spring, summer, and fall allergies for dogs?

Some allergies in dogs can have seasonality; that is, they are more prevalent or severe during certain seasons. While symptoms differ between individuals, here are some general rules for the most common dog allergies:

  • Food allergies are not seasonal in most cases because the dog has been eating the ingredient all year.
  • Flea allergies can affect dogs in the spring, summer, and fall. Veterinarians sometimes see the worst flea allergies in the fall when the fleas have had all summer to multiply and the flea quantities are highest.
  • Tree and grass pollen allergies can be worst in the spring.
  • Mold-based allergies can be bad year-round but are worse for many dogs in the fall and winter. Some molds will develop on fallen leaves and in damp, moist basements.
  • Dust mite allergies can be bad year-round but some dog owners find them worst in the winter once the house is shut up and dogs have less exposure to the outdoors.

Many dogs will begin to develop allergies between the ages of one and two years and will become allergic to more things as they age. Some dogs will appear to have seasonal allergies early in life which will become more consistent as they develop more allergies to more things. Dogs with severe allergies will eventually be itchy year-round.

Seasonally-affected dogs may not need medications during certain parts of the year. Close observation and good records may help to identify seasonal dog allergies and keep them manageable.

What causes dog allergies?

Most scientists believe that dog allergies are an inherited disease. Once a dog is diagnosed, minimizing exposure to the offending problem is one option. Treatment to control the symptoms and the body’s response to the allergens is another.

How do you diagnose dog allergies?

Most dogs with allergies are diagnosed on the basis of their history and their physical examination. To determine their specific allergies, skin testing and/or blood testing may be required.

The first step that most veterinarians recommend when examining a dog with suspected allergies is to rule out other causes of itching such as skin parasites (demodectic or sarcoptic mange) or fungal infections (such as ringworm, also called dermatophytosis). Diagnostic tests may include fungal cultures or skin scrapings to look for the parasites.

How can I tell what my dog is allergic to?

It can be very difficult to tell what a dog is allergic to. The best way is for skin testing or blood testing.

Below are some guidelines to help you understand more about the most common dog allergies and what might be affecting your dog.

  • Flea allergy dermatitis is the most common allergic skin disease seen in the United States. Dogs with flea allergies 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 differentiate this disease from atopy. It is possible, however, to see atopy and flea allergy in the same animal. Like food allergies, atopy is sometimes responsive to corticosteroid (hormone) treatment.
  • Dogs with allergies secondary to atopy usually begin to develop symptoms relatively early in life, often by one year of age. Symptoms are usually 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, they tend to become allergic to more substances. Eventually, their itchiness can occur year-round.
  • Food allergies in dogs commonly cause a pruritic skin condition. As with atopy, dogs with food allergies 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 difference to remember is that atopy symptoms usually begin between one and four years of age whereas food allergies can begin at any age. A dog with an onset of symptoms who 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 such as prednisone. Food allergies are variably responsive to prednisone; only about 50 percent of affected dogs will see improvement after treatment.

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How are dog allergies treated? Treatment for skin allergies in dogs

Treatment for skin allergies in dogs may include medications that can alleviate symptoms, but they do not treat the underlying cause of the allergy. Caring for dogs with allergies is extremely frustrating; allergic reaction is a life-long disease with no easy “cure.”

Immunotherapy (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 allergy. However, the recommendations for your allergic dog will depend on your dog’s underlying symptoms (such as healing skin infections, irritation caused by itching, and ear infections that require medication) as well as the treatment for the potential causes of allergic reactions such as fleas

Your veterinarian may recommend the following for dog allergy care:

  • Flea control medications (for dogs with flea allergies)
  • Limited ingredient diets (for dogs with possible food allergies or multiple allergies)
  • Antihistamines including Benadryl, Chlortrimeton, and Zyrtec; there are many on the market, and some dogs will respond to one antihistamine but not another so many pet owners try a variety before concluding they don’t work.
  • Fatty acid supplements to relieve itchiness by modulating the immune response; certain fatty acids such as eicosapentanoic acid (found in fish oil) help change the chemical composition of cell membranes and, ultimately, the types of chemical mediators produced during the allergic response, which results in a milder response from the body. Like antihistamines, these products are not helpful in all affected animals, but they are very safe. Some dogs that do not respond well to antihistamines may respond to a combination of antihistamines and fatty acids.
  • Antibiotics to treat secondary bacterial infection of the skin (called pyoderma) or ear infections; yeast infections of the skin and ear also have to be treated occasionally.
  • Topical therapy for skin wounds (often a spray of a solution of an antibiotic and steroid)
  • Soothing and therapeutic shampoos; topical therapy may be very helpful in managing itchiness caused by allergies. Shampoos that contain colloidal oatmeal are soothing and moisturizing and can be used frequently without drying the skin. Some oatmeal-based shampoos contain topical anesthetics or corticosteroids that are very safe and help further reduce itchiness.
  • Corticosteroids (cortisone-like drugs such as prednisone); these are very effective at reducing the symptoms of allergies, but they have many potential side effects that limit their long-term use. This class of drugs is very effective in allergic dogs; unfortunately, these drugs also have many potential adverse effects that restrict their long-term use. Examples of the adverse effects of corticosteroids include increased water consumption and urinations, increased appetite and food intake leading to obesity, suppression of the immune system leading potentially to secondary infections, irritation of the stomach, alterations in liver function tests, and suppression of normal adrenal gland activity. Short-acting, orally-administered corticosteroids are safer than long-acting injectable corticosteroids because the former can be cleared rapidly from the animal's body in the event of adverse effects. Any dog that can be helped by long-acting injectable corticosteroids can be relieved just as effectively and with less risk by the use of short-acting orally-administered corticosteroids.
  • Immunotherapy (hyposensitization, desensitization, allergy shots); this is theoretically the ideal form of treatment for dog allergy care and is recommended for dogs that cannot be managed safely and effectively with symptomatic therapy. The exact mechanism by which immunotherapy works is not well understood, but the goal is to induce tolerance of the immune system to allergens to which the animal is sensitive. This technique is effective in 60 to 80 percent of atopic dogs. An extract of the allergens selected by allergy testing is prepared. Initially, a small amount is injected frequently (every 1 to 2 days), and the dosage is gradually increased. Due to the frequency of injections, your veterinarian may show you how to administer the injections at home. Once the cumulative dose reaches a certain level, the injection interval is slowly increased until injections are given every 2 to 3 weeks. The interval then may be maintained for a relatively long period of time. Improvement is gradual, and your dog may not benefit markedly for the first 3 to 6 months of immunotherapy. Antihistamines, fatty acid supplements, and soothing shampoos may be used while immunologic tolerance develops.
  • Use of an immunomodulator drug called cyclosporine A (Atopica®, Novartis); cyclosporine has properties that fight against inflammation and itching. It is generally started daily and often decreased to every other day or every third or fourth day as clinical signs improve. It may take four to eight weeks to see improvement.
  • A newer therapy called Oclacitinib (Apoquel); this drug has been very effective in controlling itching in dogs with allergies. It uniquely targets cytokines that are involved in the itching process. The onset of relief can be as early as 4 hours, and treatment controls the itch within 24 hours. Many veterinarians like this drug because it controls itching without the side effects of steroids.

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