Page 1470 - Clinical Small Animal Internal Medicine

1408 Section 12 Skin and Ear Diseases

Several factors can influence the results of allergen atopic dermatitis show reactions to allergens which can-
VetBooks.ir testing, including time of year (particularly if seasonal not easily be avoided or eliminated. Pollens, for example,
are essentially impossible to eliminate. Owners will often
variation is noted), strength of allergens, and significant
inflammatory skin disease (either due to atopic dermati-
the dog or cat is exposed (e.g., removing problematic
tis alone or other concurrent pruritic dermatosis). ask about changing the immediate environment to which
Additionally, administration of antipruritic pharmaco- trees or grasses from the property). However, the spread
therapy can dampen or mask “positive” test results. This of aeroallergens can have an approximately 100 mile
is especially true for intradermal allergen testing. A radius or more, depending on environmental conditions.
recent review proposed optimal and minimal withdrawal The statement “if it is not in your own yard, it might be in
times of antipruritic drugs prior to allergen testing. your neighbor’s” holds a large amount of truth.
Based on a review of the current literature, antihista- There is a large market as well for avoidance and reduc-
mines should be withdrawn for at least seven days, oral tion of house dust mite allergen (the most common envi-
and topical glucocorticoids (including otic preparations) ronmental allergen implicated in atopic dermatitis in
for at least 14 days, and a minimum of 28 days for longer‐ dogs worldwide). Special air filters, pillow, and mattress
acting injectable glucocorticoids (although many derma- covers are designed to reduce the load of house dust mite
tologists recommend at least 4–8 weeks withdrawal) in the environment, and household cleaning products
prior to intradermal allergen testing. There was insuffi- have been designed to kill and thereby reduce house dust
cient evidence to make recommendations for medica- mites in the home. These measures do not completely
tion withdrawal prior to serology allergen testing; these eliminate allergens from the environment and therefore
tests may be less influenced by the presence of antipru- are insufficient on their own to reduce severity of dis-
ritic pharmacotherapy but care must be taken with ease. Decreased exposure, however, may allow for a
regard to interpretation of results. reduced flare of atopic dermatitis and/or provide benefit
as an adjunct intervention with additional therapeutic
measures. Additional recommendations for improved
Therapy allergen avoidance include frequent washing of pet and
household bedding, maintained replacement of air filters
in the home, avoiding fresh cut grass (for pollen aller-
As with people and other domestic animal species, there gens), and frequent bathing.
is no cure for atopic dermatitis in dogs or cats. However,
the disease can be fairly well managed with various ther- Bathing and Other Topical Therapy
apeutic interventions. Therapy falls into two categories: Along with mechanical removal of environmental aller-
medical and allergen‐specific immunotherapy. Medical gens, bathing provides additional therapeutic benefit to
therapies aim to primarily address the pruritus and the atopic dog. Shampoos containing antipruritic ingre-
discomfort associated with atopic dermatitis, whereas dients such as colloidal oatmeal, pramoxine (topical
allergen‐specific immunotherapy attempts to “retrain” analgesic), antihistamine, or glucocorticoids are often
the immune system, shifting back towards a more “nor- recommended as maintenance therapy for the allergic
mal” Th1 response as opposed to Th2 dysregulation. dog; interestingly, however, studies have not documented
improvement with any specific ingredient over another.
Medical Therapy A small study evaluated a lipid and complex sugar‐
containing shampoo with and without the addition of
With regard to medical therapy for atopic dermatitis, whirlpool bathing; bathing with the shampoo showed
interventions span the spectrum from fairly conservative evidence of clinical reduction of pruritus, which was
to more aggressive. Options for conservative therapy reduced further when a whirlpool was also used. Taken
include implementation of environmental allergen together, the physical act of bathing may be the most
avoidance, bathing and other topical therapy, antihista- important factor for providing relief to the pruritic dog
mines, and essential fatty acid administration. More as opposed to a specific ingredient or formulation. The
potent, “aggressive” medical therapy includes adminis- above ingredients, however, are benign and often owners
tration of systemic glucocorticoids, ciclosporin, or oclac- feel their pet experiences more beneficial results when a
itinib. Additional/alternative therapies have also been particular product or ingredient is used.
evaluated with variable success. Bathing is typically recommended once every 1–2
weeks long term. In the face of an allergic flare, more
Avoidance frequent bathing may be beneficial. In dogs where sec-
Avoidance of environmental allergens can be rather ondary bacterial or yeast skin infections are contributing
difficult, particularly since many dogs and cats with factors associated with atopic dermatitis, shampoos