Allergies to dogs are caused by dog dander. All dogs shed dander continuously. Dander is the microscopic bits of hair and skin that have a protein-based oil secretion on them. Because the dander varies slightly from one dog to another, it is possible for a person to have an allergic reaction to one dog and not another, even if it is the same breed. The symptoms of an allergic reaction to dogs are usually noticeable when you enter an area where the dog has been.
Allergies to dogs may cause a rash or tiny bumps on the skin. The rash is usually itchy. In some cases, this skin irritation will be located only where the dog has had direct contact with you. However, because dog dander is airborne, it is possible for this symptom to appear in areas that haven't had any contact with the dog.
A runny nose and asthma-like symptoms are common signs of an allergy to dogs. If you start having these symptoms, wheezing or shortness of breath only when you are near a dog, you may be allergic to the dog. Generally, the symptoms can be alleviated with an over-the-counter allergy medication. However, children and those who are very sensitive to the dogs may need to consult an allergist for immunosuppressive therapy.
Itchy eyes are another sign of an allergic reaction to a dog. Generally, this symptom will only be present when you touch your eyes with something that the dog has touched. However, if there is a considerable amount of dander around you, it is possible for your eyes to water without touching the dog.