Allergy Testing

How Are Environmental Allergies Properly Diagnosed?

The hallmark feature of environmental allergies (atopy/atopic dermatitis) is itching behavior (physical scratching, licking, chewing, rubbing, scooting, etc.).  Secondary skin and ear infections are common.

Environmental allergies are diagnosed:
1) A history compatible with seasonal itching/allergy symptoms that completely go away in non-peak seasons
2) Ruling out an underlying food allergy with a prescription diet trial (not all prescription foods are created equal; some are more likely to fail than others)
3) Ruling out skin parasites that can cause itching, including flea allergies (not all flea medications are created equal; some are more likely to fail than others)
4) Ruling out possible hormonal diseases that can cause skin infections, which can mimic allergies.

Does Blood "Allergy" Testing Diagnose Allergies? - NO!

Blood allergy testing or allergy skin testing are not accurate ways to diagnose allergies in animals with "skin problems."

Some veterinarians will recommend allergy testing for the diagnosis of allergies, before thoroughly ruling out other IMPORTANT causes of ITCHY skin diseases. This can lead to misdiagnosis and treatment errors. For example, a dog with food allergies or a hormonal disease process (i.e. Cushing's disease) and secondary bacterial or yeast skin infection could be itchy. A blood allergy test could produce positive results, indicating that the dog has IgE against certain allergens. This IgE is not likely to be clinically important for that dog, yet the positive test could result in a mis-diagnosis and erroneous treatments. Although veterinary dermatologists understand the potential for any dog to have positive blood allergy test results, veterinary dermatologists strive to educate clients, and veterinarians on best practices for diagnosing environmental allergies. Serological (blood) tests are IgE tests, NOT allergy tests.

Are There Any Reliable Blood Allergy Tests That Can Be Performed To Determine Food Allergies? -NO!

There are no reliable skin or blood allergy tests to predict food allergies in veterinary medicine.  While they do exist, we sincerely wish they didn't AND we sincerely wish veterinarians would avoid recommending them.  They are a waste of money!  Numerous studies have shown that blood and saliva tests for food allergies often yield positive test results, EVEN IN HEALTHY DOGS WITHOUT FOOD ALLERGIES.  At DCA, we sincerely want to help to identify or completely rule out a food allergy.  A food allergy can generally be cured and can generally be completely controlled.

I've Tried Every Diet At The Pet Store.  Doesn't That Rule Out A Food Allergy? - NO!

Numerous independent studies have consistently shown that OVER THE COUNTER diets, INCLUDING RAW DIETS, and TREATS contain cross contamination of other protein sources; they are not made under strict, sterile, conditions and are not suitable for testing assessments.  This is similar to peanut allergies in humans!

What Are The Common Food Allergens?

Beef, chicken, dairy products, eggs, fish and wheat.   Furthermore, patients who are allergic to chicken may also likely react to duck or turkey.  Patients who are allergic to beef may also likely react to venison, lamb, or bison.  PROTEINS MATTER!

How Can I Fully Determine If My Dog Has A Food Allergy?

A strict diet trial, for at least 8 weeks, using a PRESCRIPTION hypo-allergenic diet is the most reliable means for determining a food allergy.  Prescription foods are made under strict, sterile, conditions.  Be careful, your veterinarian may not be recommending the best/most reliable foods when screening for food allergies!

What Does DCA Recommend When Screening For Food Allergies?

We have the MOST confidence and best success with using the RAYNE NUTRITION Rabbit with Quinoa or the RAYNE NUTRITION Plant Based diets, as a means for screening for food allergies.  As a veterinary dermatology/Allergy clinic, if there was a better food to help identify and/or control food allergies, we would use them/recommend them!

How Strict Does The Food Trial Need To Be?

Completely strict!  If a human had peanut allergies, would they eat something with just a little amount of penauts?  How about just 1 single peanut?  No other flavored medications, treats, supplements, or monthly flavored preventatives (Nexgard, Simparica Trio, Heartgard, Interceptor/Sentinel, Trifexis, and more), should be given during the food trial.  A substitute, non-flavored, or topical option should be recommended.  We see food trial failures due to flavored medications daily, because veterinarians overlook this little detail!

What Is A Hydrolyzed Diet?

A prescription diet where the protein has been enzymatically broken down into small fragments that, IN THEORY, the body DOES NOT react to.  Many veterinarians believe hydrolyzed diets are the best and guaranteed to work but, in veterinary medicine we only have partially hydrolyzed products; they are not 100% hydrolyzed, and therefore they can still elicit reactions.  DCA sees many food allergic pets fail to improve with these types of diets.  Studies have shown that 20-50% of food allergic pets can react to hydrolyzed diets.  For these reasons, we recommend Rayne Nutrition!

What Are The Least Effective Prescription Hydrolyzed Diets? 

While these diets can work, the Hills z/d (partially hydrolyzed chicken) and Purina HA (partially hydrolyzed soy) are the least effective prescription diets many dermatologists find, including here at DCA.  For these reasons, we recommend Rayne Nutrition!

Could I Try Using An Over The Counter, Limited Ingredient Diet From The Pet Store?

Every pet owner can make their owner decision on what they think is best.  But due to cross contamination of other proteins, using an OTC diet will likely lead to a return of clinical symptoms for which they may have originally came to seek help or a cure of.  Low levels of chronic inflammation can also result from being on the wrong diet which can be a known risk factor for other unwanted and serious health problems and also likely requiring to offset symptoms with expensive and potentially immune-altering medications that carry side effect potential (i.e. Apoquel, Cytopoint, prednisone, etc.).

What If The Prescription Diet Trial DOES NOT Alleviate The Symptoms?

Generally, this would likely suggest an environmental allergy.  Another prescription diet trial may be suggested, in some cases.

What Is The Goal Of Allergy Testing?

Once a true diagnosis of environmental allergies is made, THE REASON veterinary dermatologists recommend allergy testing is to help formulate allergen-specific immunotherapy.  Numerous studies have shown that blood allergy testing results do not correlate with allergy SKIN testing.  If not all of the allergens are truly known/identified, treatment will likely be unsuccessful.  While desensitization therapy can be effective in up to 75% of patients, and improvements can be seen within 4-6 months, it can take up to a full year, (12) months, for the full maximum effect.  If effective, this treatment would be life long.  Human treatment protocols are generally a 3-5 year commitment!

Does Simply Knowing What My Pet Is Allergic To Help Me?

Environmental allergies are often numerous and rarely only allergic to 1 single thing.  Allergy avoidance (putting an animal in a bubble) is impossible.  

What Are The Symptoms Of Environmental Allergies?

The hallmark feature is ITCHING (i.e. licking/chewing of the feet, legs, groin, flanks, rubbing of the face/eyes, and anal gland issues).  Atopy is a progressive disease.  While it might begin very seasonal, it can also progress to become more and more year round.  Many environmentally allergic pets will have secondary skin and/or ear infections too!

What Are The Most Common Environmental Allergens?

Common allergens include pollens of grasses, trees, weeds, molds, and dust and storage mites. 

Could My Pet Be Allergic To Fragrances, Detergents, Or Cat Litter?

Because animals are generally covered in fur, these type of contact reactions (allergy), while possible, are extremely uncommon.  Humans or animals with little coverage of fur/hair, are more susceptible to these issues.

What Are The Treatment Options For Environmental Allergies?

The majority of medications used for environmental allergies help to reduce ITCHING!  These medications can also help with other allergies or sources of itching (i.e. food allergy and flea allergy).  IF YOUR PET DOES NOT EXHIBIT ITCHING, THESE MEDICATIONS WILL NOT LIKELY BE EFFECTIVE.  If your dog has environmental allergies and itching behavior, these medications will likely be needed, and may have to be continued, so long that the itching symptoms continue to persist.

1) Steroids (prednisone): this is the most effective treatment for environmental allergies in dogs and cats.  It has be around the longest AND ALL medications that have been released for environmental allergies have been and will always be compared to steroids because of how effective steroids are in reducing itching.  Although not the most ideal, some patients who fail to improve with use of other medications, may have no choice but to consider long term use of steroids.  Common and expected side effects generally include increased drinking behavior, increased urination, ravenous appetite, and panting.  More serious side effects, especially with higher dosages and DAILY DOSAGES: Increased risk for diabetes, exacerbation of kidney and heart problems, and CALCINOSIS CUTIS.

2) Apoquel (Dogs only): This is an ANTI-ITCH MEDICATION.  DCA ONLY RECOMMENDS ONCE DAILY DOSING. Apoquel is a Janus kinase inhibitor.  This medication targets T cells and modifies and prevents the release of IL-31, which is a known cause of itching.  This medication bears a close resemblance to Xeljanz, for the treatment of rheumatoid arthritis in humans.  This medication will generally relieve itching symptoms within a few hours after administration and itching will return, generally, the next day. Do not use APOQUEL in dogs less than 12 months of age or those with serious infections. APOQUEL may increase the chances of developing serious infections, may cause existing parasitic skin infestations or pre-existing cancers to get worse and could lead to bone marrow suppression. Consider the risks and benefits of treatment in dogs with a history of recurrence of these conditions. New neoplastic conditions (benign and malignant) were observed in clinical studies.  In some cases this medication may stop working over time.  THIS IS NOT A TREATMENT LABELED FOR USE IN CATS; DCA DOES NOT RECOMMEND USE OF APOQUEL IN CATS, due to overall lack of efficacy and overall lack of safety studies in cats.  Apoquel IN CATS CAN LEAD TO ELEVATED KIDNEY VALUES.

3) Cytopoint (Dogs only): This is also strictly an ANTI-ITCH MEDICATION.  Cytopoint is a CANINE monoclonal antibody that neutralizes IL 31 and saturates the IL 31 receptor, thereby blocking the itching pathway to the brain.  This is considered to be a very effective and very safe, and targeted, treatment option for itching.  Cytopoint will generally relieve itching within 24 hours and the itching will generally go away for approximately 30 days; in some cases it may last up to 6-8 weeks.  In some cases it will only provide itch relief for 2-4 weeks, or in some cases it does not work.  In some cases this medication may stop working.  THIS MEDICATION IS NOT APPROVED FOR USED IN CATS.

4) Atopica (cyclosporine): Another ANTI-ITCH MEDICATION.  This medication does not work overnight.  This medication will generally take 2-4 weeks to be effective and reduce itching.  Many dermatologists will prescribe this once daily for 30 days then attempt to decrease the frequency down to every other day there after.  This medication also targets and modifies T cells, helping to prevent the release of pro-inflammatory cytokines involved with itching.  Similar side effects as mentioned for Apoquel apply to this same drug.  Common side effects generally include GI upset: vomiting and diarrhea.  THIS MEDICATION IS ALSO APPROVED IN CATS.  This medication ONLY WORKS to help reduce itching associated with environmental allergies.

5) Allergy desensitization therapy: based on allergy testing, a treatment is formulated based on the results of the allergy test and a treatment is administered either in the form of allergy shots or allergy drops (sublingual).  If environmental allergies are diagnosed properly and if all allergens are fully identified based on proper allergy testing, this treatment can be effective in up to 75% of patients, where it can either allow the individual to become tolerant of the allergens or it may help decrease the amount and frequency of other medications used.  Although many patients may begin to show improvement within the first 4-6 months, it may take up to one full year before a full response is noted.  This treatment would be continued, if effective, indefinitely.

6) Bathing 1-3 times weekly: while this may not be possible for every owner, and especially in cats, bathing could help to reduce surface allergen load.  If no skin lesions are present, use of an oatmeal-based shampoo could be soothing.  If secondary skin infections and lesions are present, use of an antibacterial/antimicrobial treatment is generally recommended.  Use of a product such as MiconaHex Triz either in a shampoo, spray, or mousse form, is generally recommended.

7) Antihistamines: antihistamines (Benadryl, Zyrtec, or prescription strength) only block the release of histamine and not inflammatory mediators such as steroids, Apoquel, or Cytopoint.  For these reasons, antihistamines are generally mediocre, if at best.  Benefits of antihistamines, especially Benadryl, could include sedation and lack of desire to itch.

8) Fish oils/Free Fatty Acids: numerous supplements exist with claims of improving allergy symptoms and reducing itching.  These are considered mediocre, if at best.  These are considered harmless but not generally effective.

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We were so lucky to have met Dr. Mel

Cindy Hollingsworth Knoxville, TN

Have a Question?

Have a question regarding service? Wondering if we can help? Ask us!

Telephone: 206.508.5500

Fax: 206.508.5520

Our building is located 2 blocks North of REI.
Free parking is available on the rooftop of the building.


Parking Directions from I-5
Take the Mercer Street exit

Turn left onto Fairview Ave N

Turn left onto Republican St

Continue on Republican St 1/2 block past Yale Ave

On the right hand side there will be an alleyway - Turn Right down the alleyway located between Ripple Yoga and Evolve Fitness

Within 30 feet on your right hand side, make a slight right onto the open air roof top - Park only in parking stalls labeled 'DCA' (parking stalls 20-23)

Stairs are located in the SW corner of parking lot taking you to Yale Ave (in front of stall 21)

Our clinic will be to the right of the stairway as you come down from the parking lot.


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