Because house dust mites and storage mites are microscopic, the general feeling about them among clients could be "How much
harm can they cause my pet?"
In fact, the most common allergen in dogs and cats (and in people, too) is dust mites. Anyone who is allergic to dust mites
can attest to the miserable symptoms this condition can cause. It seems our domestication of dogs and cats (i.e., bringing
them into our households and beds) also succeeded in sensitizing them to this common allergen.
Here are answers to several frequently asked questions about house dust mite and storage mite allergies.
Where are dust mites found?
Dust mites (Dermatophagoides farinae, Dermatophagoides pteronyssinus) reside in textiles such as carpet, bedding, mattresses, upholstery and cloth toys. They prefer a specific temperature and
humidity to flourish, which is easy to come by during periods of sleep. Mites have translucent bodies and prefer the dark,
and they like a sleeping body that is exhaling warm, moist air.
Dust mites feed on human skin scales, bacteria, fungi and viruses in the environment. They prefer the skin scales of atopic
individuals because their skin lipids differ from nonatopics (Photo 1). The actual source of the allergen is the protein Der
p 1, which is found in dust mite feces.
Photo 1: Facial excoriation in an atopic cat that is dust mite allergic.
What are the signs of dust mite allergy in pets?
Such allergies tend to be nonseasonal, but they can peak in the spring and fall. In dogs, recurrent pyoderma, pruritus (generalized
or involving the face and feet), recurrent otitis or seborrhea—i.e., all the usual signs of atopy—may be present (Photo 2).
Cats may show eosinophilic granuloma complex lesions, pruritus, chin acne, recurrent otitis or plasma cell pododermatitis
(general signs of atopy).
Interestingly, 30 percent to 80 percent of atopic dogs and cats skin-test positive to dust mites. In my experience, some pets
that formerly lived outside can become sensitized after a period of time once brought to live inside.
What's the best way to determine if an animal has dust mite allergy?
The history of signs in the pet should be one of nonseasonality, with food allergy and ectoparasites ruled out. The pet can
then be tested either via skin or serum for an IgE reaction to dust mites. D. farinae is more common in the United States, while D. pteronyssinus is more common in the United Kingdom, but both species exist in both countries.
The pet's clinical signs are usually responsive to corticosteroids; however, this is not diagnostic. Dust mites are acarids
and belong to the same order as Sarcoptes, Otodectes and Cheyletiella species mites and food storage mites. So they may cross-react with one another on skin testing—i.e., if a patient has scabies,
it may have a false positive test result for dust mites.
What are the treatments for dust mite allergy?
Once it's been proven a pet has this allergy, immunotherapy (subcutaneous or sublingual), treatment with cyclosporine, corticosteroid
administration and/or environmental treatment should be undertaken. Matthew Colloff (in Dust Mites, 2009)1 scientifically evaluated all the methods for environmental treatment of dust mites (avoidance is preferred but unlikely),
with the best being airing out fabrics on a hot, sunny and dry day or a cold and dry day for 12 hours followed by vacuuming.
Advise clients to use microporous mattress covers and to wash bedding in hot water (> 122 F [50 C]) monthly or in cold water
using tea tree oil. If possible, remove carpets from bedrooms. Vacuum weekly all carpets and upholstered furniture by using
a HEPA-filter vacuum, or steam clean mattresses, animal bedding and upholstery.
The study found that air ionizers and chemical dust mite "killers" are not as effective. The only chemical agent that helped
a little was benzyl benzoate, but it had to be used at four times the recommended amount and left on carpets for l2 hours