Westbury Animal Hospital
713.723.3666 · 4917 S. Willow Dr. Houston, Texas 77035 

“Help, my pet won’t stop scratching….” (The frustrating facts about allergies)

Dr. Victoria Cole

Having an itchy pet can be very frustrating.  The scratching, chewing, licking and rubbing is unfortunately a very common complaint for both cat and dog owners.  The behavior is not only irritating, but can also lead to secondary infections, wounds, odors and a poor quality of life.

The two most common causes of an itchy pet are external parasites (such as fleas, or the mange mite) and allergies.  Allergies in our pets more commonly result in skin and ear issues (rather than upper respiratory signs like we see in humans). Our pets often develop red, itchy skin, hair loss, as well as recurring skin and ear infections.

Types of allergies:

Three major types of allergies in our pets are a flea allergy dermatitis (FAD), a food allergy, and atopic dermatitis (atopy).

Flea allergy dermatitis (FAD) requires 100% flea control. The bite of a single flea can result in a severe flare-up for the patient and you do not need to actually see any fleas for the pet to be affected. Even if you do not see the fleas, they may be present and could still bite.  Year round flea prevention is strongly recommended and your veterinarian can assist you in choosing the best type of flea prevention for your pet. 

Food allergies can develop later in life as it takes time for the hypersensitivity to develop.  Therefore, developing a food allergy is not necessarily associated with a recent change in food. A food allergy can affect the gastrointestinal tract but is more likely to affect the skin.  There is no accurate blood or skin test to diagnose a food allergy.  A veterinarian will likely discuss a “food trial.”  This entails starting the patient on a novel protein (a new protein source that the patient has never eaten before- ie venison or duck); or a hydrolyzed protein (one that is broken down so small that the body does not recognize it to react (ie z/d or hypoallergenic prescription diets).  The food trial must be very strict for 10-12 weeks; during this time there can be no other treats, no flavored medications, or chewable toys.  After the 10-12 week trial is complete, a “food challenge” should be performed at which time the previous food is reintroduced and a 2 week monitoring period to see if the clinical signs of the allergy return. Classic food allergy symptoms include itching the face, feet, limbs, rectum and recurring ear infections.  (Cats appear to be more affected at the face, neck).

Atopic dermatitis (Atopy) is an inherited allergy to common inhalants or environmental particles (ie pollen, grass, trees).  This means that the allergy develops in those pets who are genetically programmed to be allergic.  Certain breeds are predisposed (Dalmatian, Golden retriever, Westie, Shar Pei, Labrador retriever, Cairn terrier, Lhasa apso, Shih tzu, Boxer, Pug).  Atopy is a clinical diagnosis and testing of the skin or blood can help look for antibodies but does not definitively confirm a true allergy.  Atopy can be seasonal but after time, the “itchy period” can get longer and even year round.  Unlike food allergies which develop later in life (onset ~5-6 years of age), atopy is often seen as a younger onset (~1-3 years).  Vaccines can be created for certain allergens to help decrease a pet’s sensitivity in order to better “manage” but not cure an allergy. 

Differentiating between a flea allergy vs a food allergy vs atopy can be very difficult and requires a very thorough history and close monitoring of patterns and response to medications.  This is best obtained with you and your veterinarian working very closely to manage your pet’s health together.

Medications for allergies can help decrease severity of symptoms but the underlying cause of the allergy still needs to be addressed.  Medications may include antibiotics for secondary skin infections, steroids, fish oil, anti-histamines, shampoos, cyclosporine (immune suppressive medications), etc. 

Allergies are a life-long problem that are “managed” not “cured.”  The goal to keep in mind is to control allergies and improve quality of life for both the pet and us as owners. 


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