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Allergens Demystified

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Although the symptoms are usually different, both pets and humans tend to become allergic to the same things. This article runs through some of the most common environmental substances that trigger allergic reactions, so you can avoid them as much as possible.


Indoor Allergens


“Dust” is composed of dust mite feces, particles and cells from human or animal skin, bits of decayed insects, mold and mildew spores and pollen, bacteria, viral particles, plus a little dirt. When you see dust motes in a beam of sunlight coming through a window, that’s what you are looking at. We breathe and touch all these fine particles all day long. People or pets with allergies to components of all this fine dust are constantly exposed to it.

The components of dust and air vary with the seasons. In spring there is a lot of tree pollen in the air. In late summer there is a lot of ragweed pollen, a common allergen for pets as well as people. In wet weather there will be more mold and mildew spores in the air – and in the leaves and dirt that dogs sniff around in. Depending on what the pet is sensitive to, symptoms may wax and wane with the seasons.


Dust Mite—The allergens within dust mites are distributed through the by-products of the dust mite – in other words, their feces and bits of dead mites floating around in the air.  Dust mites are present in our homes all year ‘round. They feed on bits of debris such as skin cells (dandruff), so they tend to hang around where people and pets spend the most time.

The most common areas in which dust mites can be found are carpets, bare floors, furniture upholstery, pillows, mattresses, box springs, stuffed animals, books and in high humidity and damp areas.  Many of these are very difficult to isolate a dog or cat from. Therefore, a maximum amount of cleaning is advocated where mite allergies are a problem.  In cases where they occur in carpet, vacuuming regularly with special HEPA filter bags is indicated.  Bare floors should be mopped and dusted at least 3 times a week. A HEPA filter on the furnace or ductwork is also helpful to filter dust mite dander out of the air.


Specific things you can do to decrease dust mite habitat in your home:

   If you have the option to remove carpeting or rugs, especially older ones, do so. Wood, tile and linoleum harbor far fewer mites and mold spores.

   It’s the same with upholstered furniture – more wood, less fabric and stuffing, if possible. Old couches and chairs are likely to harbor more mites than newer furniture.

   Remove heavy draperies and try to keep window treatments simple.

   Keep books in closed glass front cabinets rather then on open shelves.

   Use plastic mattress and pillow covers and launder bedding frequently in hot water.

   Dog beds harbor a lot of mites. Look for mats that are vinyl covered & avoid beds that look like furniture or carpet. Wash bed covers frequently in hot water if the bed has a cover.

   Donate or discard stuffed animals once your kids are older.

   Dust frequently by wiping with a damp cloth or spray – don’t feather dust or you will put it all back into the air.


Grain & storage mites – These microscopic creatures move into open containers of food remarkably quickly. Within a couple of weeks of opening a new bag of pet food there will be mites in the bag & in a few more weeks there will be thousands of them. Keep pet food and bulk human food in airtight containers to deter grain mites.


Kapok—Kapok is typically found in furniture upholstery, pillows and in stuffed animals.  If your pet is allergic to kapok, isolation of the patient from such areas or removal of those items from the home are indicated.


Cockroach—The allergen from the cockroach includes secretions and feces.  Bits of dried saliva and insect poop float around in the air as tiny particles. If roaches are present, the allergen is widely distributed in house dust. Concentrations are highest in kitchen areas; however, it is detectable throughout the house. 

            Roaches generally live in moist and shady areas.  They prefer temperatures around 84ºF and do not tolerate cold.  Cockroaches are common in basements, sewers and crawl spaces, as well as cracks and crevices in porches and foundations.  They may enter the house via sewer connections, under doors, around utility pipes and through air ducts.

            There are ways to get rid of roaches that don’t involve spraying toxic chemicals in your home. Using diatomaceous earth powder strategically can dry the insects out and kill them. Keeping all food waste and crumbs off counters, floors and tables, and keeping sinks and counters dry, removes food and water sources that sustain them.


Cat Allergen—Most domestic cats commonly carry large quantities of allergen.  The highest concentration is on the area of the neck, with males shedding a far larger amount of allergen than females.  The dander is very lightweight and difficult to remove. Dogs can be allergic to cats just as humans can.


Dog—The belief that short-haired dogs are less likely to shed allergen is a myth.  Some breeds however do shed less than others, and if kept clean and trimmed will cause less problems. Cats can develop allergy to dogs.

            Regular bathing of dogs and cats helps reduce their allergen.  Allergen reduction typically only lasts a few days and therefore bathing or rinsing is required 2 to 3 times a week if a patient is allergic to an animal in the home. Bathing too frequently can dry out the skin, which can increase the amount of dander floating in the air. Rinsing a pet down with distilled water can wash a lot of dead skin cells & hair off, decreasing the amount floating around in the air.


Human - When we allergy test pets, we also are now testing for allergy to humans. Sadly, our pets can be allergic to us, as well as the other way around. Luckily, we don’t shed nearly as much hair into the environment as our pets do!


Orris Root (apparently a corruption of “Iris” root)—Orris root are the rhizomes of three species of iris.  They are often used as a fixative in potpourri to enhance color and fragrance as well as certain cosmetics, and can be recognized by their violet-scented fragrance.


Jute/Sisal—Jute is the softest among the plant fibers and is generally used as a base for inexpensive hand-woven Persian rugs.  Sisal comes from a spiky indoor plant called the Sisal bush.  Sisal carpets are very popular, particularly as wall-to-wall type carpeting.



            Molds can be found almost anywhere, and all molds produce airborne spores.  Typically their growth is stimulated by warmth and increases in humidity.  They tend therefore to be most prevalent during hot humid months.  Basements, compost piles, cut grass, barns and wooded areas are spots for finding large populations of molds.  In an older bathroom, a hot shower will also temporarily increase the mold population.  Therefore, molds typically will and can be found in almost any and every home and office environment, both indoor and outdoor. 

            The important point about mold allergy is that it is often related to an overgrowth of Candida; this yeast causes cross-reactivity to many other yeasts and mold fungi.  Once a Candida allergy is triggered, the patient may experience allergies to more common molds.

            The following is a list of ways in which mold population can be decreased or diminished to a large extent:


  • Keep humidity lower than 35% if possible and not more than 50%.
  • Use air conditioning or dehumidifiers in the summer and spray the air filter with mold-killing spray.
  • Ventilate the house—a tightly closed house encourages mold growth.
  • Keep refrigerators clean.
  • Empty water pans below self-defrosting freezers.
  • Clean garbage cans frequently.
  • Make sure tiles, shower stalls, tub, toilet tank and ceilings are cleaned regularly with a mold-killing solution.
  • Dark closets tend to be high breeding spots for molds. Placing a low wattage light bulb in the permanently on position can dramatically reduce this.
  • A good solution for killing mold is equal parts of household bleach and water.


While molds in general can be found in all the areas listed above, the following are more specific habitats for some individual molds. If we have done allergy testing and we know exactly which species a pet is sensitive to you may be able to further control that specific type.


  • Cladosporium—Grows on plants, leather, rubber, cloth, paper and wood.  One of the most common causes of mold allergy.
  • Aspergillus—Found in soil, damp hay, on grain and on fruit.
  • Phoma—Grows on magazines, books and other paper products.
  • Pennicillium—Grows on fruits, breads and cheese.  A mutant form of the penicillium mold is used in the manufacture of penicillin.  Allergy to penicillium spores, however, should not be confused with allergy to penicillin as a medication.
  • Alternaria—Often found growing on carpets, textiles and horizontal surfaces such as window frames.  Also found in soil, seeds and plants, as well as in water-damaged buildings.
  • Helminthosporium—Best known as parasites of cereals and grasses.  Frequently they are isolated from grains, grasses, sugar cane, soil, and textiles.
  • Rhizopus—Typically found in children’s sand boxes, in clusters of pine needles and leaves, sweet potato, strawberries, stewed fruit, and amongst the nest, feathers, and droppings of wild birds.
  • Curvularia—May cause leaf spots and seedling blight.  Also seen on castor beans, cotton, rice, barley, wheat, and corn.
  • Candida albicans—Very seldom found as an airborne mold spore.  They are common in soil, organic debris, and in humans as a saprophyte in the nasal pharynx and feces.
  • Fusarium—Widely distributed on numerous grasses and other plants and is a common soil fungus.  Major parasites of rice, sugar cane, sorghum, and maize grains.  Also occurs regularly on fruit and vegetables.
  • Pullularia—This is the dominant fungus found on leaves.  It also grows in the surface layers of many types of soils and is most prevalent following treatment of the soil with nitrogen fertilizer.  It has also been isolated from grasses, seeds, honey comb, nests and feathers of living birds, frozen fruit cake, leather, cotton fabrics, and concrete surfaces.
  • Nigrospora—Most commonly found as a plant parasite.
  • Smuts—Most often found on corn, grasses, weeds, flowering plants, and other fungi.  Usually the spores are disseminated by wind.
  • Stemphylium—Isolated from dead plants and cellulose material.
  • Stachybotrys—Thrives on water-damaged cellulose material such as sheet rock, paper, ceiling tiles as well as cellulose-containing insulation backing and wallpaper.
  • Saccharomyces—This is common baker’s yeast.



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