Diagnosis of Animal Allergies

When an allergy to dogs, cats, or other animals is suspected, the physician takes a medical history and performs allergy tests (e.g., scratch tests, blood tests). If possible, the animal is temporarily removed from the environment and the environment is thoroughly cleaned to determine if symptoms improve.

Scratch tests involve applying suspected allergens and then scratching the skin to introduce the substances into the skin. These tests, which are usually performed on the forearm, upper arm, or upper back, allow several allergens to be tested at the same time. Allergic reaction (e.g., itching, redness, swelling) usually occurs within 20 minutes.

Blood tests include the radioallergosorbent test (RAST), which is used to detect an allergic reaction. In this test, a sample of blood is taken, mixed with the suspected allergen, and the level of immunoglobulin E (IgE) is measured. IgE is an antibody produced by the immune system that indicates an allergic reaction.

Treatment for Animal Allergies

The proper treatment of pet allergies requires removing the animal from the environment and avoiding contact. If the animal is not removed, the Asthma and Allergy Foundation of America makes the following recommendations:

  • Add an air cleaner (e.g., HEPA [high efficiency particulate air] filter, electrostatic filter) to central heating and air conditioning and use the filter for at least 4 hours each day.
  • Bare floors (e.g., hardwood, tile) and walls are best. If carpeting is necessary, choose those with low pile and steam clean them often.
  • Cover bedroom vents with a filtering material (e.g., cheesecloth).
  • Have the pet brushed thoroughly daily (outside) to remove dander and washed every week.
  • Keep the animal out of the bedroom of the allergic person and clean the bedroom thoroughly.
  • Use a vacuum with a HEPA (high efficiency particulate air) filter if possible and wear a dust mask to vacuum.

These recommendations may not produce significant relief of symptoms and are not as effective as the removal of the pet from the entire indoor environment.

Treatment for dog, cat, and other animal allergies may include over-the-counter or prescription medications such as antihistamines and decongestants. First generation antihistamines (e.g., Benadryl, Dimetap Allergy) may cause drowsiness, but newer medications (e.g., Allegra, Claritin, Zyrtec) have few side effects (may cause dry mouth and drowsiness). First generation antihistamines may cause irritability and restlessness in children.

Oral decongestants (e.g., Sudafed, phenylepherine) may be used in combination with antihistamines to reduce allergy symptoms. Side effects of these medications include nervousness, difficulty sleeping, increased heart rate, and high blood pressure.

Topical and nasal decongestants (e.g., Afrin, Neo-Synephrine) are not suitable for long-term treatment because routine use causes rebound nasal congestion when the medication is discontinued. Nasal corticosteroids and nasal antihistamine sprays provide relief of symptoms and can be used indefinitely.

Animal allergies that trigger asthma may be treated with the following:

  • Bronchodilators (e.g., albuterol [Ventolin], Proventil])
  • Corticosteroid inhalers (e.g., Flovent, Azmacort)
  • Leukotriene antagonists (montelukast sodium [Singulair])
  • Omalizumab (Xolair)

Allergy vaccine therapy (also called allergy shots or immunotherapy) may be used to treat animal allergies when medications are ineffective. This treatment involves regular (usually once or twice weekly) injections of small doses of the allergen to reduce sensitivity.

In most cases, it takes several months for allergy vaccine therapy to be effective and treatment must be continued for a long period of time (e.g., 2 to 5 years or more). Unfortunately, immunotherapy has not been shown to be as effective as removal of the pet from the environment.

Publication Review By: Michael Miller, M.D., F.A.C.P.

Published: 09 Feb 2005

Last Modified: 22 Jul 2015