AIRBORNE ALLERGIES (ATOPIC DERMATITIS)
Airborne particles (pollens, danders etc.) are harmless to someone who is not allergic to them.
Breeds predisposed to develop atopy
FEATURES OF ATOPY
There are many reasons for pets to itch: parasites, allergy to flea bites, food allergy, secondary infection and the list goes on. The following are findings in the history and examination of the patient that might lead to a diagnosis of atopy. (In fact, meeting 5 criteria from this list yields an 85% accuracy for the diagnosis of atopic dermatitis, at least for dogs:
A few reactive blebs on an intradermal skin test
In cats, the irritation pattern is not as characteristic. There are four common manifestations of atopy:
Unfortunately, these same irritation patterns can be found in numerous other skin conditions and, in fact, up to 25% of atopic cats have multiple types of allergies.
Many patients will not be particularly itchy in between infection flare-ups so it is especially important that these be controlled.
Hyposensitization (Allergen Specific Immunotherapy)
Hyposensitization, more commonly known as "allergy shots," is by far the treatment of choice of atopic dermatitis. All the other medications are basically just itch relief; only hyposensitization actually changes the immune system. Some dogs are eventually able to go off all treatment and are no longer allergic after they have been on hyposensitization long enough. Most dogs are at least much better and require fewer additional treatments.
In hyposensitization the patient is injected with small amounts of allergens on a regular basis. As time passes, the amounts of allergens increase and injections are given at longer intervals. The selection of allergens is made based on the results of either an intradermal skin test (as described above), an “in vitro” test (a blood test) or a combination of the results of both tests. The younger the pet when this treatment starts, the better it works. For more details on allergen specific immunotherapy click here.)
These cortisone-type medications (prednisone, prednisolone, triamcinolone, dexamethasone etc.) tend to be useful as the "first line of defense" against itchy skin. A higher dose is used at first but this is quickly tapered down once the condition is controlled. Prednisone, for example, is given every other day so as to allow the pet one day of recovery from the prednisone's hormonal actions. An atopic pet will usually respond within days.
Steroid hormones are very useful for acute flare-ups as well as for long term management of atopic dermatitis (assuming limits are placed on how long they are used).
Cyclosporine is a modulator of the immune response that has been very helpful in organ transplant patients both human and non-human. It has been found to be reliably effective in atopic dermatitis and does not carry the unpleasant side effect profile that steroids do. That said, it is not without side effects of its own. It is used mostly in dogs but can also be used in cats. It is for long term management and is not helpful for acute flare up control. For more details on this medication click here.
This is a new medication best used for itch relief and blocking itch symptoms. It has been especially popular as it works very fast. It does not address the inflammation in the skin; it just stops the itch sensation. This means that infection still needs to be controlled. For more details visit: www.Apoqueldogs.com
Canine Atopic Dermatitis Immunotherapeutic (Cytopoint®) Injections
This is a new treatment which uses vaccine technology to eliminate one of the main mediators of itch sensation. The injections provides relief from itching for 1 month in 80% of dogs and show effectiveness usually within 24 hours of the injection. For many dogs, relief of itch stops the vicious cycle of itch/infection. Again, infections, if present, still need treatment but the sensation of itch is usually controlled.
Proper Coat Hygiene/Removing Allergens From the Environment If Possible
Omega 3 Fatty Acid Supplements
These products are NOT analogous to adding oil to the pet's food. Instead, these special fatty acids act as medications, disrupting the production of inflammatory chemicals within the skin. By using these supplements, it may be possible to postpone the need for steroids/cortisones or reduce the dose of steroid needed to control symptoms. It takes a good 6 weeks to build up enough omega 3 fatty acids in the body to see a difference.
Antihistamines have been popular for many years for pets, it seems their effectiveness does not stand up to scrutiny. They do not provide either short term relief nor reliable long term relief. They may be helpful in combination with other products in that their use may reduce the need for other products. They may work better in cats than in dogs.
Solid Flea Control
Allergies are additive. This means that when a patient has multiple allergies, each allergy alone may not be enough to cause itching but the allergies all active together probably will. Consequently, taking away one of the active allergies may be enough to allergy reduction to resolve the itching. Flea bite allergy is extremely common. We now have so many effective products available that there is no reason for an animal to contend with a flea bite allergy. This simple bit of therapy (flea control) may be enough to bring the pet below his or her itch threshold without having to contend with any of the therapies listed above.
Itchy skin has been the scourge of dogs and cats for decades if not centuries. We are now armed with great understanding of immunology and have many tools to address allergy symptoms. Your veterinarian can guide you further with regard to a proper regimen or you may wish to consider seeing a veterinary dermatologist for more specialized guidance.
IS YOUR PET A CANDIDATE FOR SKIN TESTING?
Testing is best done during your pet's non-itchy season (if there is one) so that the skin responses of the test will not be clouded by active inflammation. The test involves injections of small amounts of allergen extracts into the skin. Reactions noted are compared to reactions produced by two controls: pure histamine (very inflammatory) and pure saline (very non-inflammatory).
In order for skin testing to be performed, medications must be discontinued well in advance. How long in advance depends on the medication and on the policies of the veterinary dermatology practice that will be doing the test. Oral steroids, for example, commonly require a full month discontinuance, which can be problematic if the pet is highly dependent on medication for life quality.
IN VITRO TESTING?
In vitro testing does not always require withdrawal of medications nor does it require referral to a specialist. There is no hair clipping and sedation is rarely necessary. Blood is simply drawn and checked for antibodies against common allergens for that geographic region. A profile is reported and allergens can be selected accordingly. It is important to remember that these results do not necessarily imply that the patient is allergic to substances reported; this is simply a test for antibodies. Antibody elevations are very common with levels changing based on an assortment of factors (whether the pet has parasites at the time of the test, how common the substances being tested are, how long medications have been used prior to the test etc.) and interpretation of the profile is part of the “art of veterinary practice.”
For more details on what is involved, see our page on Allergen-Specific Immunotherapy (Allergy shots).
To find a veterinary dermatologist in your area, visit the web site of the American College of Veterinary Dermatology at www.acvd.org.
Page last updated: 1/8/2019