Dermatophagoides Farinae Allergy in Cats

The dust mite is a cosmopolitan pyroglyphid, which is small and barely visible without the help of magnification. They feed on the flakes of shed skin of people and pets. Dust mites do not drink water, instead, they absorb water from the humidity.  Therefore, dust mites thrive in warm and humid climates.  The two most common dust mites are Dermatophagoides farinae (American house mite) and Dermatophagoides pteronyssinus (European dust mite). These two species of dust mites can be found throughout the world. The male dust mite can live 10-19 days and the female can live up to 70 days.  A female can lay 60 to 100 eggs in her lifetime, which means her offspring will continue the cycle and multiply. Dermatophagoides farinae can be found in carpets, upholstery, curtains, bedding, pet beds, mattresses, clothing, cars with cloth seats and cloth toys. 

Dust mites allergens can trigger allergies and asthma in people, dogs and cats.  It is a very uncomfortable and irritating condition.  If your cat is showing symptoms of Dermatophagoides farinae allergy he should be seen by a veterinarian as soon as possible.

Dermatophagoides farinae is often referred to as the house dust mite.  An allergy to dust mites is a very common condition in people and their pets.  Dermatophagoides farinae is not a parasite, nor does it bite or sting.  The allergens that affect both people and pets are caused by an enzyme (Der p1), which is found in the dust mite’s feces, secretions and molted exoskeleton (cast skin).

Symptoms may include:

• Skin lesions
• Excessive scratching
• Patches of hair loss
• Acne on chin
• Recurrent ear infections and inflammation
• Seborrhea - red itchy rash with white scales
• Pillow foot - diseased foot pads

Allergic asthma symptoms may also include:

• Acute respiratory distress 
• Coughing
• Wheezing
• Sneezing
• Watery eyes
• Gagging

The allergy to Dermatophagoides farinae is caused by the allergen Der p1, which is found in dust mite’s feces, secretions and cast skin. An allergen is a substance that causes an allergic reaction.  The allergen Der p1 can enter the body via inhalation, the mucosal membranes and/or through the skin.  The immune system of a cat that is hypersensitive to Der p1 will start producing antibodies to attack the allergen.  The antibody will then attach to the allergen.  The antibodies then trigger the body to release histamines and other chemicals that result in allergy symptoms.

The veterinarian will want to go over the cat’s medical condition and will then perform a physical exam on your cat.  The examination may include taking the patient’s weight, temperature pulse and blood pressure.  He may also listen to your cat’s heart and lungs using a stethoscope.  

The veterinarian may perform a skin scrape to rule out parasites.  Cats with respiratory issues will need to have chest x-rays.  Your cat may need to have sedative in order to take the x-rays.  The x-rays will show if there is fluid in the lungs and if the bronchioles are inflamed.    The veterinarian may want to order a complete blood count and a serum chemistry test.  If Dermatophagoides farinae allergy is suspected, the doctor will also recommend a skin or serum test for sensitivity to dust mites.

Patients diagnosed with dust mite allergy who are suffering from severe respiratory distress may need to be hospitalized.  The bronchodilator albuterol may be prescribed and administered through inhalation therapy.  Other medications that may be prescribed to cats with a dust mite allergy are steroids and antihistamines. Patients with open lesions may also be given antibiotics to help prevent a bacterial infection.  The veterinarian may recommend immunotherapy, weekly allergy shots or under the tongue drops. To help remove the allergens from the skin, a medicated shampoo may be suggested.

Additionally, the household must be treated for dust mites. All bedding and blankets must be washed in hot water. The cat’s bed and cloth toys must also be washed in hot water.  Carpets, upholstery, curtains, and cat towers should be vacuumed and treated with an anti-dust mite spray. The car’s cloth seats and carpet should also be vacuumed and treated.  There are dust mite covers available for mattresses. An air purifier and the replacement of the air conditioner filter may also help to eliminate dust mites.  Re-treatment of the household should be done every 4-6 months to help prevent another dust mite infestation.

The recovery of Dermatophagoides farinae allergy in cats has a good prognosis.  The patient will need follow up visits to ensure that his skin is healing properly.  Cats that experienced respiratory issues will need to have x-rays retaken, to make sure there is no longer inflammation to the bronchioles.  Steroid medications have side effects such as increased hunger, thirst and may suppress the immune system. It is important to prevent the recurrence of dust mites.