Dog Allergies – Causes, Signs and Symptoms, Treatment

Dog Allergies

Also called: Canine Allergies


Dog allergies are a common form of allergy in the United States. According to the American Academy of Allergy, Asthma and Immunology (AAAAI), nearly 10 million pet owners are allergic to their animals.

Dogs can cause allergic reactions in people with allergies specific to dogs and in people with allergic asthma, a condition in which asthma symptoms are triggered by an allergic reaction.

Symptoms of allergic reactions to dogs include sneezing, itchy and watery eyes, coughing, wheezing and difficulty breathing. In rare circumstances, dog allergies cause the severe and potentially life-threatening allergic reaction known as anaphylaxis. Allergic reactions may be triggered by proteins in dog dander (small flakes of skin), as well as proteins in dog saliva, blood or urine.

For most allergies, the main form of treatment is avoidance – completely avoiding contact with the allergen to prevent an allergic reaction from occurring. For dog owners with allergies, avoidance is not easy. However, there are options that can lessen or relieve symptoms. These include medications such as antihistamines and decongestants, as well as allergy shots (immunotherapy).

Many pet owners will be able to control their allergies without taking the drastic measure of finding a new home for their dog. However, individuals with significant dog allergies, or dog allergies that trigger asthma, must remove their dogs.

About dog allergies

People with dog allergies have allergic reactions after coming into contact with dogs. Contrary to popular perception, it is not the dog’s fur that causes most of these reactions.

A dog allergy occurs when the body’s immune system overreacts to a normally harmless substance associated with the dog, usually proteins in flakes of skin (dander), urine, saliva or blood. The protein enters the body and starts a cascade of events that triggers the immune system and eventually leads to an allergic reaction.

How this reaction manifests itself often depends on the individual. However, an allergic reaction can affect the skin, gastrointestinal tract, respiratory system, or even the heart and blood vessels. Symptoms of allergies are sometimes confused with other causes, such as colds or the flu. In addition, dog allergies can trigger asthma attacks in susceptible people. Studies have shown that up to 67 percent of children with asthma are sensitive to animal allergens.

Direct contact with a dog is not needed to develop an allergy. Flakes from dander and dried saliva and urine proteins are extremely lightweight and easily become attached to larger particles, which can become airborne or stick to surfaces or objects. These particles remain in the environment for weeks or even months after a dog has departed. Researchers have documented the presence of dog allergens in homes, office buildings and other environments where dogs did not live. In some cases, the amount of dog allergen found was quite high. Therefore, people can experience an allergic reaction to a dog without ever having any direct contact or sharing an environment with the animal.

A few people have allergies to fleas, and a flea–infested dog may trigger an allergic reaction. In this situation it is not the dog but the fleas that are the source of the allergy. People with flea allergies develop intense itching and reddening at the bite site.

According to the American Academy of Allergy, Asthma and Immunology (AAAAI), nearly 10 million pet owners are allergic to their animals. Dog allergies may not develop quickly, and it is not unusual for dog allergies to take more than two years to develop. Puppies produce less dander than adult dogs which is why people, especially children, with dog allergies may be able to tolerate puppies but not adult dogs.

Dogs and cats are the primary causes of animal allergies. This is likely due to the fact that they are the pets most commonly kept inside of the house. However, other furred or feathered animals (e.g., ferrets, hamsters, guinea pigs, monkeys, horses, rabbits, birds) also cause allergies. People with dog allergies can safely keep pets without fur or feathers, such as fish, snakes and turtles.

Potential causes of dog allergies

Dog allergies are caused by the proteins found in dog dander, saliva, blood and urine.

Dander (tiny flakes of dead skin) is continually shed by animals. Proteins that are secreted by oil glands in the dog’s skin are also attached to this dander. Since dogs are constantly shedding dander, allergens are deposited around any area in which the animal is present. Dander is also carried by air currents, even into areas where the dog has not been. In contained areas, such as a home, the accumulation of dander is more likely to trigger an allergic reaction in people with dog allergies.

Saliva, urine, blood and dander allergens are present in all dogs and there is no such thing as a non–allergenic dog. Sensitive people may have an allergic reaction to any dog regardless of hair length or type, size or breed. Small dogs are just as likely to cause an allergic reaction as large dogs.

However, some dogs shed their skin more quickly than others. Poodles and schnauzers shed their skin about every three weeks. Cocker spaniels, German shepherds and Irish setters shed their skin every three to four days. It is possible that the dog breeds that shed their skin less frequently may produce less dander. People sensitive to dog dander will be sensitive to all dog dander. For highly allergic individuals, the actual amount of dander produced by the dog may be irrelevant.

Related allergies and conditions

Dog allergies are related to a number of other conditions, including other allergies. People with pollen or dust mite allergies may be more likely to also have dog allergies. Also, people with outdoor allergies might experience reactions after contact with a dog, even if they do not have a dog allergy. This is because outdoor allergens such as pollen and mold can get caught in the dog’s fur.

Specific allergies are not inherited, but the tendency to develop an allergy is inherited. If a parent is allergic to dander, for instance, a child has a higher likelihood of developing an allergy of some type, although not necessarily to dander. The risk of developing an allergy is much higher if both parents have allergies. People who are prone to develop allergies are said to be atopic.

Allergies to dogs may trigger other medical conditions. Some of the common conditions related to dog allergies are:

  • Allergic rhinitis. An inflammation of the mucous membranes that line the nose causing nasal congestion, sniffling and sneezing. Dog allergens can cause allergic rhinitis.
  • Allergic conjunctivitis. An inflammation of the tissue lining the inside of the eyelid that produces irritation and tearing of the eyes. Dog allergies can cause acute allergic conjunctivitis symptoms.
  • Contact dermatitis. An inflammation of the skin that is caused by direct contact with an allergen. A red, bumpy rash may appear when the skin comes into direct contact with dog dander, saliva, blood and urine.
  • Asthma. A condition in which the airways become blocked or narrowed causing shortness of breath and breathing difficulty. Asthma can be allergic or non–allergic in origin. Dog allergens can cause both acute and chronic (ongoing) asthma symptoms. The incidence of asthma–like symptoms in dog owners is significantly higher than those who are exposed to other animals. There is also evidence to suggest that people with dog allergies have an increased risk of developing chronic asthma.

Signs and symptoms

The signs and symptoms of dog allergies are similar to those of other allergic conditions. Symptoms may include:

  • Sneezing
  • Coughing
  • Wheezing
  • Shortness of breath  
  • Stuffy nose
  • Itchy and watery eyes
  • Skin rash

The severity of allergic reactions to dogs varies between patients. Highly sensitive people may begin experiencing symptoms within 15 to 30 minutes of exposure to dog allergens. People who are less sensitive may not develop symptoms for several days after contact with the allergens. The level of dog allergens in an environment also plays a role in the timing of a patient’s symptoms. Symptoms typically occur sooner when allergen levels are high.  

In rare circumstances, a person with a dog allergy experiences anaphylaxis. This is a severe potentially life-threatening allergic reaction that requires emergency medical attention. Symptoms of anaphylaxis include:

  • Shortness of breath
  • Tightness in the chest
  • Swelling of the lips, face, throat or tongue
  • Lowered blood pressure

Diagnosis, treatment and prevention

Physicians trying to determine the cause of an allergic reaction will compile a medical history and a list of symptoms. They will also perform a physical examination.

In addition, an allergy skin test may be performed to help diagnose the patient. This test involves introducing a small amount of an allergen to the patient’s skin to determine if the person is allergic to that allergen. If a rash or small bump develops, the patient is most likely allergic to that substance. Physicians who suspect a dog allergy typically test for dander first. If the test is negative, the physician may test for other allergens, such as saliva and urine.

Alternatively, a physician may order a blood allergy test. These tests look for the presence of allergy–specific immunoglobulin E (IgE) in the bloodstream. The most commonly used blood test for allergy conditions is the radioallergosorbent test (RAST).

The main form of treatment and prevention for dog allergies is avoidance – completely avoiding contact with dogs to prevent the allergic reaction from occurring. However, many dog owners are unwilling or unable to part with their pet.

Therefore, treatment for dog allergies may also include medications like antihistamines and decongestants, as well as allergy shots (immunotherapy). People who choose to keep their dogs can also lower their risk for symptoms by keeping the animal out of their bedroom. They should also avoid petting, kissing or hugging the animal.

However, it should be noted that individuals with significant dog allergies, or dog allergies that lead to asthma, must remove their dogs.

In the rare instance when anaphylaxis occurs, the patient will require immediate medical attention. An injection of epinephrine is required to reverse the patient’s symptoms.

Questions for your doctor

Preparing questions in advance can help patients to have more meaningful discussions with their physicians regarding their conditions. Patients may wish to ask their doctor the following questions about dog allergies:

  1. Do my symptoms indicate a dog allergy?
  2. What tests will you use to determine if I am allergic to dogs?
  3. Is it dangerous for me to have a dog?
  4. Are certain breeds less likely to cause a reaction?
  5. What are my treatment options?
  6. I am not willing to give away my dog. How can I reduce my exposure to allergens?
  7. Is my child more likely to have dog allergies because I have the condition?
  8. Does having a dog increase or decrease my child’s risk for allergies?
  9. Is it likely I am allergic to other animals as well as dogs?
  10. What affect will having a dog allergy have on my asthma?
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