What is an allergy?

Like people, pets can develop irritating allergies. However, pets’ allergies seldom manifest as the classic hay fever signs seen in people, but rather as itching, scratching, and hair loss, in addition to watery eyes and sneezing. An allergy is a hypersensitivity of the immune system to typically harmless environmental substances. Pets can suffer from the same allergies as people, even to other pets and their dander, and are often allergic to multiple allergens.

What causes allergies in pets?

Allergies, which can be induced by any object in your pet’s environment, are divided into three categories:

• Food allergies alone are challenging to diagnose, and diagnosis is made more difficult by the fact that 30% of food-allergic pets also have another allergic skin condition. To add to the confusion, many people believe pets are allergic to grains, even though grain allergies are rare. A pet most likely is allergic to a protein source, such as chicken, beef, lamb, eggs, dairy, or fish. Food allergies are often seen after a pet has eaten the same food all her life, and is pushed over her allergy threshold by the chronic exposure to the allergenic food source.
• Flea allergies are so common, they have their own category. Flea allergies also are caused by a protein found in flea saliva that can cause allergic flares in hypersensitive pets from a single flea bite. Veterinary-approved flea prevention administered year-round is critical to prevent flea-allergy reactions and to keep your pet comfortable. Give your indoor-only cat preventive also, even if she is not allergic to fleas, because she can harbor adult fleas and contribute to your home’s flea population. She may even become allergic to fleas with enough exposure. Flea allergies are rising in cats. One study found a 67.3% increase in flea-allergic cats, compared with a 12.5% increase in dogs, in the past 10 years.
• Environmental allergies include any other substance your pet may be exposed to  through inhalation or contact. Common environmental allergens include:
  • Pollen
  • Mold
  • Dust mites
  • Dander
  • Fabrics
  • Feathers
  • Medications
  • Cleaning products

Environmental allergens can vary by location and climate, so your pet may suddenly develop allergies if you move, even from a rural area to the city. Environmental allergies, such as those triggered by dust mites or cleaning products, usually flare up in spring and fall, the most common allergy seasons, but may affect pets year-round.

How are allergies diagnosed in pets?

Accurate diagnosis of the allergenic culprit is challenging, since many signs are similar in each allergy category. You may notice the following signs in your allergic pet:

• Itching
• Hair loss
• Chronic ear infections
• Licking or chewing at paws
• Red, inflamed, or sticky skin

Flea allergies are often the easiest to diagnose. If your pet shows evidence of live fleas and the classic sign of hind-end hair loss, your furry friend is most likely suffering from a flea allergy.

Environmental allergies can be diagnosed using two testing methods:

• Intradermal testing: This test involves shaving your pet’s side and injecting small amounts of allergens under her skin. We then chart the local allergen response to determine its severity. With the information about your pet’s allergens, we can choose the appropriate management course that will keep her comfortable.
• Serum testing: We take a small blood sample from your pet for allergy analysis. We send the sample to an outside laboratory, which measures the allergy antibodies in the blood to determine your pet’s allergens.

Food allergies are the most difficult to diagnose. Serum testing is available, but it is not recommended or validated. We recommend a food trial, which can pinpoint the allergy most accurately. First, give your pet a novel food with a foreign protein source, such as duck, bison, or venison, that she has never eaten before. Food trials with pet store brands can be challenging due to cross-contamination, so we recommend using a specifically formulated prescription diet or a hypoallergenic diet to avoid contamination.  Then, feed your pet nothing else but the trial food for six to eight weeks—that means no treats, flavored toys, or flavored medications. Ideally, your pet’s signs will subside and reappear if you reintroduce the old food.

Understanding and diagnosing your pet’s allergies can be a long, tedious process, but we are here to help. If you think your pet’s itching may be caused by allergies, schedule an appointment at our hospital to determine the cause of her scratching and to discuss management options.