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Ask the Vet: Do Allergy Shots Work in Dogs? (Immunotherapy)

Whether allergy shots work in dogs is something owners of allergic dogs may wonder about. Owning an allergic dog indeed can be quite a frustrating ordeal and dog owners may want to find ways to alleviate their dogs' allergies. In order to understand how dog allergy shots work, it helps to gain a better understanding on what happens to the dog's immune system when there is an allergy, the most common allergies in dogs and how dog allergy shots, also known as immunotherapy, works. Veterinarian Dr. Ivana provides clarifications on how dog allergy shots work.

 Dogs with allergies often itch and lick. Dog allergy shots may give relief.

Dogs with allergies often itch and lick. Dog allergy shots may give relief.

A Dog's Allergic Response in a Nutshell

Infectious agents normally stimulate the immune system to produce protective antibodies. Allergens, usually harmless substances that are inhaled or swallowed, or that come into contact with the skin or eyes, provoke the immune system to mistakenly produce an antibody called immunoglobulin E (IgE).

In allergy prone dogs (about 15 percent of the total dog population) a set sequence follows. First, IgE binds to receptor sites on specialized immune system cells called mast cells. These immune cells are like primed mines, filled with 10 different chemicals. Mast cells exist in the skin and the lining of the stomach, lungs and upper airways. It is believed that mast cells originally developed to attack internal parasites such as intestinal worms and lungworms.

When the dog is exposed to the same allergen again, the substance binds to IgE, already bound to mast cells. This reaction causes mast cells either to release some of their chemicals contents or to explode, releasing inflammatory substances such as histamine and prostaglandin.

People have lots of these mast cells in their noses and eyes, and so commonly react with upper respiratory symptoms. On the other hand, dogs have most of their mast cells in the skin and consequently react with itchiness. In dogs, allergies may also affect one or more regions of the gastrointestinal system.

Just like allergies tend to run in some human families, there is also a breed predisposition in dogs. The Chinese Shar Pei and Japanese Akita seem particularly susceptible to allergies. Several breeds with predominantly white coats, such as West Highland White Terriers, Bull Terriers, and English Setters, are predisposed to produce excessive IgE and consequently have a higher than normal incidence of skin allergies. Golden Retrievers and West Highland White Terriers have higher incidence of gastrointestinal allergies. Acquired sensitivities may develop later in life.

Types of Allergies in Dogs 

The house dust mite, flea saliva, and human dander are common causes of allergies in dogs. By selective breeding, humans have increased the genetic predisposition to allergies in some dogs, and by altering their environment we have also increased dogs’ exposure to potential allergens.

The following points are some helpful questions to ask when trying to decide if a sick dog has an allergy.

  • Has the problem occurred before?
  • Does it occur at a specific time or season?
  • Does it occur in a particular environment?
  • Are the ears involved?
  • Is there any history of allergies in the dog’s breed or immediate family?

If the answer to most of these questions is yes, then an allergic cause is probable. There are several common types of allergies in dogs, here is a brief rundown of them.

Allergic Inhalant Dermatitis

Inflammation can be triggered by allergens that are absorbed through the skin, but more frequently by allergens that are inhaled into the respiratory system. In such cases, only some dogs develop respiratory problems. Many others exhibit their allergic response through itchy skin inflammation, especially on the face, feet and ears.

Allergic Contact Dermatitis 

In this condition the allergic reaction occurs only on parts of the body in direct contact with the allergen. Grass sap, for example, causes dermatitis on the relatively hairless underside of the dog’s body.

Hives also Known as Urticaria

This condition, a form of localized and often itchy swelling, is most likely to be triggered by biting or stinging insects, food allergies and drug reactions.

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Hay Fever 

While common in people, hay fever (or allergic rhinitis) is relatively uncommon in dogs. In dogs inhaled allergens are more likely to trigger itchy skin rather than sneezing and drippy noses. When hay fever does occur, the allergens are the same as for humans: dust, pollen, dander, mold spores and cigarette smoke.

Allergic Bronchitis

Inhaled allergens rarely cause an allergic response in the nose. In fact, they are more likely to do so in the air passages (trachea and bronchi) and the lungs. Allergic bronchitis causes a dry, honking cough, similar to that associated with kennel cough.

Allergic Pneumonitis

If the smallest air passages in the lungs are involved in an allergic reaction, an affected dog shows signs of pneumonia. Blood samples show excess numbers of white blood cells called eosinophils. Samples of fluid washed out of the dog’s trachea may also contain these white blood cells. The condition is sometimes called PIE (pulmonary infiltrate with eosinophils). The recovery takes several weeks.

Allergic Gastrointestinal Conditions

Allergy is a common cause of a group of disorders called inflammatory bowel disease or IBD. Each affected dog experiences a unique form of IBD:

Allergic gastritis – manifested with periodical vomiting of bile-tinged mucus, usually several hours after eating or rhythmically, at certain times of the day.

Allergic enteritis – manifested with loose, watery, smelly diarrhea, sometimes accompanied by bile-tinged vomiting.

Allergic colitis – manifested with bloody diarrhea.

It should be noted that food allergies may cause no gastrointestinal problems, but may trigger an allergic response in the skin, sometimes confined to the face or ears. For more on this read:dog food allergies versus environmental allergies. 

Do Allergy Shots Work in Dogs? (Immunotherapy)

Immunotherapy is the treatment of choice for dogs that do not respond well to conventional allergy medication and for dogs experiencing allergy symptoms all year round. Immunotherapy works better in younger than in older dogs. According to statistics, in 60 and 80 percent of the dogs with environmental allergies there is no need of additional allergy management once the immunotherapy is completed.

The concept of immunotherapy is based on introducing the dog’s organism with small amounts of allergens to which the dog is allergic. Slowly, over time, the allergens’ doses are increased. The end goal is for the dog to gradually build tolerance to the introduced allergens.

In most cases, the immunotherapy is administered via injections under the dog’s skin. Rarely, it can be administered in the form of liquid droplets under the tongue. If injections are used, they are applied every other day at first and then the frequency is decreased to once or twice a week. If oral drops are used they need to be applied twice a day.

The immunotherapy is used for at least one year and then its effectiveness is evaluated. During that first year, in addition of the immunotherapy shots, the dog also receives its usual anti-allergy medications.

About the Author

Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.

ivana crnec

She currently practices as a veterinarian in Bitola and is completing her postgraduate studies in the Pathology of Domestic Carnivores at the Faculty of Veterinary Medicine in Zagreb, Croatia.

Ivana’s research has been published in international journals, and she regularly attends international veterinary conferences.

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