Many pets (and people) suffer from allergies to the components of “house dust”.  The main culprits here in the north are the microscopic house dust mites and molds. Cockroaches factor into the mix farther south. House dust is made of microscopic house dust mites (alive and dead)  and their tiny fecal pellets of half digested food, flakes of skin from you and your pets, bacteria, viruses, and fungi as well as non-organic debris.

Within a short time after construction, all enclosed dwellings have some house dust, no matter how often or how well you clean.  In fact, the act of cleaning may actually stir up this dust and increase allergy symptoms temporarily.

House dust mites are related to spiders and scorpions. Our two main house dust players are Dermatophagoides farinae  and Dermatophagoides pteronyssinus.  House dust mites are the most common allergens in dogs, cats, and people!   They feed on skin flakes, bacteria, viruses, and fungal spores.  Interestingly, they thrive especially in mattresses, the older the better, with a particular taste for those contaminated with dried semen.  Pillows, carpets, and upholstered furniture are also favorites.  House dust mites love plush!  In comparison, skin cells shed on hard, dry surfaces become too dry to attract these mites.  House dust mites actually prefer to dine upon the shed skin cells of individuals who themselves have allergic skin disease or skin cells from older people because of lower lipid (fat) levels in their cells.

Temperature and humidity are very important to house dust mites.  They need adequate moisture in their tissues to function. Additionally, skin flakes are not a balanced diet for them and they require the fungal spores to provide minerals and vitamins.  Fungi thrive in warm and humid conditions. Consequently, house dust mites love temperatures consistently between 70 and 90 degrees with high humidity.

Molds may also be allergens in some individuals.  Without allergy testing, it is difficult to determine their exact roles in the symptoms of a particular patient.  Are they a great food source for mites or are they causing allergic reactions themselves?  Molds are not always visible in your house.  In addition to adequate moisture, molds also require a nutrient substance on which to grow. Wallboard, damp wood, fabrics, leather, paper products, and the sponge at your kitchen sink are great. They can also grow on concrete or the dirt on windows or window frames. Other sources are food products, particularly vegetables, fruits, and breads.  Molds produce microscopic spores that spread through the house on air currents.


House dust mites and molds cause differing symptoms with varying intensities in different victims.  In allergic individuals, exposure to even a small amount of an allergen can cause production of a type of antibody, Immunogloulin E (IgE).  This IgE starts the allergic inflammatory response that results in any combination of the following:

Sneezing, discharge from eyes or nose, coughing, difficulty in breathing Excessive grooming Scratching/licking/chewing of paws, armpits, groin, rectal area (Light-colored fur may turn brownish from saliva staining.) Scratching ears, shaking head, reddened ears that may even feel warmer than normal Moist dermatitis (hot spots)—sudden rapidly expanding wet sores that cause uncontrollable itching and ultimately are overtaken by bacterial infection Minimize carpeted areas and fabric-upholstered furniture Clean thoroughly and frequently with central vac or vacuum with HEPA filter (and consider using a HEPA filter air cleaning system in the room where the allergy prone pet sleeps or spends a lot of time). Remove allergy patient from the environment while you are cleaning and for several hours afterwards while dust settles.  Open windows if weather is appropriate (and pollen count, smog concentrations are low). Do not smoke indoors because tobacco smoke often worsens allergy symptoms and second hand smoke is much denser at the height of your pet’s nose than it is at your own. Wash scatter rugs, cloth toys, and human and pet bedding often, preferably in hot water, weekly.  (Tea tree oil or benzyl benzoate may be somewhat effective in cold water.) Use allergen-blocking mattress and pillow covers Equip a forced air furnace or air conditioning unit with a high efficiency media filter with a MERV rating of 11 or 12.  Leave the fan on when not heating or cooling so that it continuously filters the air.  Have heating and AC units inspected every 6 months. To prevent problems with mold, Use a dehumidifier when humidity surpasses 50 percent.  Avoid vaporizers and humidifiers Use vent fans to remove moisture from bathrooms and kitchens Repair any water leaks See the following sites to further address mold:http://www.epa.gov/mold