Veterinary Dermatology Center
Robert G. Buerger, DVM, DACVD
Board Certified Veterinary Dermatologist

32 Mellor Avenue Suite B
Baltimore, Maryland USA   21228
410-788-8130
FAX 410-788-9007

www.Vderm.com

Allergies and Allergy Testing For Pets: Q & A’s

      Licking, chewing, scratching, rubbing, and head-shaking are common
signs of allergies in pets, and secondary infections (caused by bacteria
and/or yeast) can be a recurring problem.   Infection often adds to a pet’s
discomfort.  Allergies can be year-round or seasonal depending on which
allergies are present.  Symptoms most commonly start between 6 months
and 3 years of age, but they can begin at any time.  Pets typically do not
“outgrow” their allergies, and sometimes they worsen and become less
responsive to treatments with age. Early control is the goal.  The
symptoms of allergy can often be improved or controlled (but NOT cured)
with one or more of the following: antihistamines, Apoquel® tablets,
Atopica® capsules, Cytopoint® injections, medicated shampoos, and in
some cases a restricted (hypoallergenic) diet.  Cortisone medications are
often used as a last resort.  Flea prevention and maintaining a clean and mat-
free coat is essential.  Allergy testing and allergy immunotherapy treatments
should be considered if problems are prolonged (especially if they are year-
round), if symptoms are not adequately controlled with conservative
treatments, if pets require repeated courses of antibiotics or cortisone-type
drugs, or if treatments cause severe or objectionable side effects.  

How is allergy testing for environmental allergies performed?
  Allergy testing is performed either by blood testing (requires a quick blood
draw) or by intra-dermal test injections into a shaved patch on the side (with
the patient sedated).  Please note that neither blood testing nor skin testing
is helpful or accurate for diagnosing allergies due to foods.  
 

What is the benefit of allergy testing for environmental allergies?
  After the cause of the allergy has been determined through testing it can
then be treated with an allergy vaccine that is specific for those allergies.  
This is called allergy immunotherapy.  Allergy vaccines can be administered
by injection or by mouth (so-called sublingual immunotherapy).  In either
case, we can show you how to administer the vaccine.   For most pets it’s
very easy.

If my pet has symptoms suggestive of a food allergy how is this diagnosed?
  Food allergies can only be diagnosed and controlled with a strict
elimination diet that may take up to 10 weeks to show benefit.  Prescription
foods are best and the trials must be strict (no treats, chews, or people
foods).   Over-the-counter foods are not appropriate for this 10-week trial.   
Labs offer blood testing for food allergies, but the results can be very
inaccurate and misleading.  A few labs offer direct-to-owner allergy test
results based on and oral swab or hair samples from your pet, but not even
one objective study has shown that these test results are accurate.  It’s
particularly distressing that fur trimmed from stuffed teddy bears and swabs
dipped in tap water can yield positive results with these inaccurate tests.  
We’ll recommend a strict elimination diet if your pet’s symptoms are
suggestive of food allergy.  

How often are allergy immunotherapy injections administered?
  In the initial stages the injections are given on alternate days.  Gradually the
length of time between the injections increases to once every 3 weeks, but
for some pets the injection schedule may need to be modified.    Allergy
injections will likely be necessary for the life of the patient.  The injections
help to control the symptoms for most pets, but they do not cure allergies.

Are allergy injections my only option?  Is oral administration of the vaccine an
option?
  Allergy injections have been used to control symptoms for many decades,
and studies have demonstrated their usefulness.  Oral allergy
immunotherapy drops is another (newer) option to help control allergies.   
Oral allergy immunotherapy drops are administered twice daily.  For most
pets these drops will be necessary for the life of the patient.  They help
control symptoms, but they don’t cure allergies.  

How long does it take to see benefit from allergy injections or oral allergy
drops?
  While some pets improve within weeks most pets require 3-9+ months of
therapy to see benefit.  Some may take one to two years to show
improvement.  The response to the treatment may be total or it may be
partial.  If it is partial then other medications may still be needed to help
control with control of the symptoms. During the first few months of
immunotherapy (injections or oral) many pets will require additional
medications to help with comfort.  As the allergy treatments take effect and
as the symptoms subside we hope to gradually taper medications.  
  Approximately 25% of allergic pets do not show improvement with allergy
immunotherapy.  

How is my pet prepared for allergy testing?
  Cortisone tablets such as prednisone, Temaril-P, and Medrol must be
stopped at least 4 weeks prior to testing.  The waiting period may be longer
in some instances particularly if long-acting injections have been given.   
Consult your veterinarian before stopping medications as a gradual
withdrawal may be recommended.  Cortisone-containing eye and ear drops
should be stopped 7-10+ days prior to testing if possible. Antihistamines
such as Benadryl, Zyrtec, and hydroxyzine must be stopped at least 14 days
prior to allergy testing.   Apoquel tablets, Atopica capsules, and Cytopoint
injections do not have to be stopped as these will not typically affect test
results.  

Once the results of the allergy test are known, what are the long-term
maintenance costs associated with allergy immunotherapy injections or oral
allergy drops?
  Refill vials of for an injectable vaccine cost $275 and last about 6 months
with the standard injection schedule (given every 3 weeks ...life long).  The
cost of syringes is extra.  The cost of the allergy vaccine may be higher for
certain types of allergies.  Refills of oral allergy drops are $283 and vials
typically last 5 months (given twice daily....life long).  Note that the start up
vials for either oral or injectable vaccines will last about 2-3 months.   Please
reorder early when there’s about a half-inch remaining in the last vial.

If you have any additional questions please ask us at your next appointment.
                                                                                               
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Allergies and Allergy Skin Testing