Figure 2. The hyposensitization schedule for dogs weighing 20 lb or less. The client fills in the date the injections are
given and the dog's pruritus score from 0 (none) to 10 (severe pruritus).
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Allergen companies will supply the treatment protocols. The protocol begins with the lowest concentration of allergens and
gradually increases the injection volumes and allergen concentration until a maintenance dose is reached. Numerous protocols
for allergen-specific immunotherapy are used. All protocols are a starting point, and adjustments may and often should be
made based on a pet's response. For dogs, I use two different protocols, one for small dogs (20 lb and under) and one for
large dogs (over 20 lb) (Figures 2 & 3).
TEACHING CLIENTS TO GIVE ALLERGENS AT HOME
Generally, it is easiest to have clients administer the allergen-specific immunotherapy at home with subcutaneous injections
(see the client handout "Allergen-specific immunotherapy: 4 easy steps for home administration" ). Some veterinarians and owners are reluctant to do so, but most clients can easily administer the injections, and most dogs
will readily tolerate this therapy. The most demanding protocols start with an injection given every other day and end with
maintenance injections being given every seven to 30 days. This treatment protocol is certainly less demanding than that needed
to treat a diabetic dog or cat.
First, explain the protocol and appropriate vials for each segment of therapy to the client. Once the client understands what
the vials are and how the protocol works, teach him or her how to accurately draw up the appropriate amount of antigen solution.
Provide 1-ml syringes with 27-ga needles for injecting the solution into a pocket of subcutaneous tissue formed by raising
and folding the skin. In my experience and that of many dermatologists, aspiration to assess whether the needle is in a blood
vessel is not recommended with this technique and needle size because hitting a vein in the pocket is unlikely and drawing
back on the plunger with this size of needle does not readily aspirate blood unless a large vein is penetrated.
Figure 3. A similar schedule to that in Figure 2 but for dogs weighing more than 20 lb. Note the differences in the maximum
dose received and injection intervals. At the recheck examination at the end of this schedule, if the dog is doing well, you
can try to lengthen the number of days between injections.
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Tell clients to use new syringes with each injection; boxes of syringes that are not individually packaged are acceptable
and less expensive. Also counsel clients about proper syringe and needle disposal (check your area's medical waste ordinances),
preferably into a small sharps container that you send home with them, and instruct them to return the full containers to
the clinic for disposal. Be sure to warn clients about avoiding puncturing their own skin. They should be especially cautious
if they are known to have any allergies. One client who accidentally punctured his own finger while trying to give an injection
to his dog developed anaphylaxis and was hospitalized. He was highly allergic to one of the allergens in the allergen solution.10
Next, demonstrate how to give the injections. Use saline solution if the demonstration is done on the day of an intradermal
skin test because if a reaction occurs that day it can be determined that the reaction was from the intradermal test and not
from the injection. If a client is picking up the allergen solution after a blood allergy test or at least a day after an
intradermal test, then do the demonstration by administering the first dose listed on the immunotherapy protocol so the dog
can be observed for any immediate reaction while in the clinic. The client then should practice the injection in front of
the instructor with saline solution.
The injections are usually given in the dorsal lateral caudal cervical area, or the nape of the neck. It is helpful to vary
the injection locations so that the same site is not repeatedly injected. The injections can be rotated to alternate sides
of the neck as well as given slightly more cranial and caudal. Some dermatologists have the client locate the center of the
neck and vary the injection sites by visualizing a clock and giving subsequent injections at the various hours rotating consecutively
around the clock. If the injection location is not varied, pain or persistent swelling and increased skin thickness may occur,
though these problems are rare.
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