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information about allergies in pets and
what can be done to treat and prevent this
Mark P. South, B.Sc., D.V.M.
Town & Country Animal Hospital
Palm Beach Gardens, FL 33408
This time of year prompts many problems with regards to allergies in dogs and cats.
Much like hay fever in people, pets exposed to airborne allergens, either by inhalation or contact, can lead to many problems. This type of allergic dermatitis is termed atopy. The allergens involved can be many and varied and include pollens from trees, flowers, and grasses; dust, dander, smoke, and most importantly dust and house mites. The latter of these allergens have for many years been characterized as two of the most highly allergic substances affecting our pets.
The difference between inhaled allergies in people and pets is the fact that pets do not develop the conjunctivitis (inflammation of the conjunctiva surrounding the eye) and rhino-sinusitis (inflammation of the passage ways of the nose and sinuses) which affects people and which leads to itchy eyes, sniffling, and runny nose.
Instead, pets develop itchy skin (allergic dermatitis). The itching can be so intense that the pet will scratch until the skin is excoriated. Once the barrier of the skin is affected, this natural and physical defense can be infiltrated by the bacteria that normally colonize the skin and otherwise cause no problem to the pet. The most common bacteria is Staphylococcus pseudointermedius. With the skin's immunity waned and the inflammatory products causing increased blood flow to the area, this bacteria will thrive, leading to a bacterial dermatitis that continues this downward spiral with more itching, skin damage, and bacterial proliferation.
Allergic dermatitis has several factors common to this condition that can help lead to its diagnosis.
There is a genetic factor in which some pets have a normally defective epidermis (outer skin layer). In these pets, the amount of damage to the skin from itching and scratching leading to a breakdown of the immune barrier and bacterial affectation is much less than in those pets not genetically predisposed.
As alluded to in the first paragraph, seasonality is an important factor. Airborne allergens differ from season to season. Based on to what a particular pet is allergic will determine when the clinical signs are noted. In some unfortunate pets, allergies are present to allergens noted in all seasons and thus the pet will have a year long problem.
Airborne allergies tend to occur in the younger pet. Initial age of onset is approximately 1-3 years of age. In contrast, food allergies tend to occur later in life (5-6 years of age).
Pattern of dermatitis can be a common factor in different types of allergic reactions. Pets having an allergic reaction to an insect bite or vaccination, for instance, will tend to show swelling in the face, muzzle, and around the eyes. Flea allergies tend to lead to dermatitis and hair loss along the lower back and on the back end of the hind limbs. Pets with atopy (airborne allergies) tend to have hair loss and inflammation of the skin around the eyes, on all four paws, on the caudal abdomen (belly), in the armpits and around the anus.
The pattern noted in cats is different than that noted in dogs. In cats, the pattern is one of four manifestations, including: hair loss along the lower back and abdomen (fur mowing), small plaque like lesions called eosinophilic granuoma, small seed like scabs called miliary dermatitis, and face/ear itching. These patterns can be causedby many other problems in cats, so diagnosis of this condition in the cat can be quite challenging.
Diagnosis is usually based clinical history and the factors noted above. Allergy testing, either with a blood sample or intradermal allergy testing
allows for the identification of the specific allergens involved which can aid in treatment and prevention.
Treatment includes 3 facets. Minimizing allergen exposure, resolving skin inflammation, and treating secondary infection.
Decreasing exposure to allergens is difficult, at best. Allergens are everywhere and if your pet is sensitive to these allergens there is no way to prevent exposure. You can, however, wash plush toys routinely, use an air filter for your air conditioner unit with a microparticle rating of 1800 or above, keep your pet away from freshly mowed lawns, and minimize the number and types of house plants.
Resolving skin inflammation is an easier feat and requires one of several different types of medications including the following: 1. Corticosteroids. This is the mainstay of anti-inflammation in pets and people. Steroids tend to get a “bad rap” as a medication because people know that the side effects can be significant. If used properly and judiciously steroids, such as prednisolone or dexamethasone will provide significant relief for skin inflammation and itching. 2. Cyclosporine. Like corticosteroids, cyclosporine is a immunosuppressant. By suppressing the overactive immune system, skin inflammation and itching is abated. 3. Oclacitinib. This is a brand new class of drug (janus kinase inhibitor). It works by inhibiting an inflammatory pathway different and more specific than corticosteroids or cyclosporine. By being more selective in the type of immunosuppresion, side effects are fewer and less significant. 4. Antihistamines. Over-the-counter antihistamines can be effective in helping pets with mild inflammatory signs associated with allergies. Caution. Never use any antihistamine that also has a decongestant (e.g. Benedryl-D, etc) these decongestants can lead to heart issues in dogs. 5. Miscellaneous. Soothing oatmeal based shampoos and utilization of over-the-counter powders, such as Gold Bond Medicated powder, can provide relief in mild cases.
Treating secondary skin infections is, also, very straightforward with the use of the appropriate antibiotic or anti-fungal. Your veterinarian will likely recommend a skin slide cytology, in order to determine the type of organism (bacteria (rod or cocci), and/or yeast) and a culture to determine the specific organism and to what specific antibiotic the organism is sensitive.
Finally, hypo-sensitization therapy can be effective, especially in those pets who have severe conditions. With either a intradermal skin test or examination of a blood sample. The specific allergens to which your pet is allergic can be determined. This information will allow an attempt to prevent exposure or to use these allergen types in order to develop a serum that can be given to your pet in order to help your pet develop resistances to these allergen types.
A great deal can be done to help your allergic pet. Visit your veterinarian today and find out what options are present for you and your loved one.
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