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Old Dog Resources
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College of Veterinary Medicine
Louisiana State University
DERMATOLOGY SERVICE
Dr.Sandra Merchant, DVM Dr. Carol S. Foil, DVM
Diplomate A.C.V.D. Diplomate
A.C.V.D.
CANINE ATOPIC DERMATITIS
Canine atopic dermatitis (allergic dermatitis, canine atopy) is an
inherited predisposition to develop allergic symptoms following repeated
exposure to some otherwise harmless substance, an "allergen", such as dust mites
or pollen. Most dogs begin to show their allergic signs between 1 and 3 years
of age. Due to the hereditary nature of the disease, several breeds, including
Golden Retrievers, most Terriers, Irish Setters, Lhasa Apsos, Dalmatians,
Bulldogs and Old English Sheep dogs are more commonly atopic, but many dogs,
including mixed breed dogs can have atopic dermatitis. The incidence is
increasing both in man and animals.
Atopic animals will usually rub, lick, chew, bite or scratch at
their feet, muzzle, ears, armpits or groin, causing hair loss, and reddening and
thickening of the skin. In some cases several skin problems can "add" together
to cause an animal to itch where just the allergy alone would not be enough to
cause itching. These problems include air borne-allergens (pollens, etc...),
allergens in food and allergens from parasites (fleas, etc...) and also
bacterial or yeast infections of the skin. Eliminating some but not all of the
problems, may allow a patient's itchiness to go away. Therefore it is important
to treat any other problems that could be making your pet itch while dealing
with allergy.
Diagnosis: Specific diagnosis of atopic dermatitis is based upon the results of
intradermal testing and/or in vitro (blood) testing. Many
medications can interfere with our ability to properly skin test your pet.
Length of time that a medication's effect remain in an animal's body is highly
variable; however, these are basic guidelines for withdrawal of medications: At
least 4 weeks off oral prednisone; 10 weeks after triamcinolone acetonide
injection; 14 weeks after methylprednisolone acetate injection; 10-14 days off
antihistamines; 10-14 days off topical steroids (ear drops, ear drops or
medication for skin); 2 days off tranquilizers.
Treatment:
1) Antihistamines - This medication works in 20% of atopic patients. Your
pet can take antihistamines for life. The only side effect usually seen is
drowsiness. Several types may be tried to find the one best for your pet.
Topical antihistamines for the eyes can be helpful in patients with eye allergy
(itchy conjuncitivitis). Visine A is one over-the-counter product that can be
helpful.
2) Avoidance of the allergens - This can be helpful for house dust mite
allergies. We have another handout on this subject. Pollen exposure can be
reduced by using air-conditioning and air filters, avoiding the outside early
morning and late afternoon, wiping down with moist cloths after going outside
and frequent bathing.
3) Oral Steroids (prednisone, cortisone, triamcinolone, etc) - These drugs
have many potential side effects and are reserved for adult animals, those with
short seasonal problems or where other therapy is not possible or is
ineffective. Typically, treatment is started at one dose and then tapered off to
every other day usage.
4) Topical Steroids - Topical usage is safer than oral usage. It can be
very helpful if itching is localized (eg eyes, ears). It can be used for more
widespread disease in the form of leave-on rinses or lotions (ResiCORT® ) or a
triamcinolone spray (Genesis® ).
5) Cyclosporine (Neoral® ) - This is an immunosuppressive agent that
can be used at low doses to treat allergy successfully in about 60% of
patients. It can also be used to lower needed dosages of steroids. The major
short-term side effects are gastro-intestinal upset. The long-term safety is
not completely known. The dosage can often be lowered after a few weeks of
successful treatment.
6) Tacrolimus (Protopic® ointment) - This is a drug that is related
to cyclosporine. It can be very useful for treating localized itchy areas in
atopic dermatitis. It is applied once or twice a day at first, then frequency
is reduced.
7) Fatty acid supplements - Certain types of oils can reduce allergic
symptoms in some patients. We can give fish oil capsules in conjunction with a
low-fat diet or prescribe special prescription diets with the fish oil content
raised. This therapy can help improve response to antihistamine therapy.
8) Allergen Specific Immunotherapy - This involves giving an allergy vaccine
injection that is made up specifically for your pet, usually for the lifetime of
the animal. After an initial series of injections, periodic boosters will be
needed (every 1-3 weeks). 60-80% of animals will improve with the vaccine.
Results may not be seen for 3-6 months. When results are not seen in 9-12
months, a re-evaluation is necessary.
9) Bathing - Atopic skin is sensitive, and subject to drying. Only
specially designed hypoallergenic shampoos should be used on your allergic dog.
Rinsing should be thorough. Generally it is best to follow with a
hypoallergenic cream rinse or spray to remoisturize the skin after every bath.
(DELETED ALLERMYL Not sure about this yet)
Reprinted with permission from Louisiana State University School of Veterinary Medicine
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