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Allergies in dogs are a very common problem. Unlike people that develop sneezing and sniffling with allergies, most dogs develop itchy skin. This is potentially related to where histamine and other inflammatory substances are released within the body in response to an allergen (a substance that results in an allergic response). The degree of signs will vary with each patient. Not all patients are allergic to the same substances. Likewise, not all allergens are located in all geographical areas, so a patient may do well in one area, but upon moving may become allergic. The majority of allergens are dusts, pollens, wool, etc. The most common allergy in pets though, is to fleas, (the allergy is actually to the saliva from the flea bite). This makes flea control imperative in any allergy patient. Inhaled allergens are the next most important cause of allergies, (referred to as atopy) then food allergies. Patients with allergies are also more prone to secondary skin infections, (pyoderma) and to ear infections (otitis). Below is more information and things to consider in your pet:
When did your pet first develop itchiness?
Dogs less than 1 year of age may be more likely to have mites, food allergies or other causes of itchiness
Did itching develop after moving?
What time of year is your pet itchy?
A pet that is only itchy in the spring, summer or fall may only be itchy outdoor pollens, while a pet that is itchy in the winter or year-round may have more indoor allergens, multiple allergens or have food allergies.
Do other pets in the house itch or do you itch?
If you and other pets are itchy, scabies and ringworm must be ruled out
If just the pets are itchy, make sure fleas are not the problem, this is the #1
cause of allergies in dogs and cats
A thorough physical exam is an important diagnostic tool for ruling in or out certain conditions
Is the skin oily?
Is there crusting or severe seborrhea?
Are there pustules or papules?
What body areas are affected?
Is self-trauma evident?
Are the ear tips and distal limbs worse than other parts of the body?
Any moving mites, fleas ticks or other parasites found?
A sample of the crusts and oil on the skin is examined under the microscope to look for bacteria or yeast that can complicate allergic pets.
This helps to rule out scabies, this mite is difficult to find and may
warrant empirical treatment with revolution or ivomec.
Response to therapy
Response to antibiotics or cortico-steroids can help diagnose atopy. The majority of pets with allergies will respond very well to cortico-steroids.
Confirms an allergic type reaction
Rule-out other disease like pemphigus
Does not diagnose what pollen, mold etc the pet is allergic to
Strongly recommended in cases that do not respond to traditional therapy.
Determine what allergen is affecting the pet
Not all allergens can be tested for
If an allergen is found, a serum is given by injection on a routine interval (usually
Between 65% to 75% success rate (this figure varies)
Are not effective for determining food allergies
The patient should be off all medications prior to testing, preferably
Generally wait until the patient is 1 year old to get exposure to a full season of
Types of Allergy Testing
Blood tests (RAST or ELISA)
A blood sample is sent to a laboratory to screen for antibody (IgE) to specific
Simple, can be ran by any hospital
Results may not correlate quite as well as IDST
Intradermal skin testing (IDST)
Samples of allergens are injected in a grid pattern just into the skin on a
Exaggerated response indicates an allergy to a specific allergen
Usually performed upon referral to a specialist
Much discussion ongoing about value versus blood tests
Usually more expensive
Sometimes a combination of the two may be required in difficult cases
Must be with a food the pet has not been exposed to or a low molecular size
Home cooked diets are preferable, but often difficult for many owners to
Many diets are available, but no single one may be the correct in a given patient
Give only the exclusion diet, absolutely nothing else (NO Treats)
Must give at least 8-12 weeks to have a positive effect
Very effective for most atopic allergies
Effective treatment for the patient that is only itchy for a few weeks or so each year
Side effects if used chronically at high dosages
Increased drinking and urination
Thinning of the skin
Predispose to secondary infections
Not as effective for food allergies
May not be as effective after long-term use
Not recommended for long-term use
Allergy serum injections (Immuno-therapy)
Determined based on blood tests or skin testing
Recommended for pet with chronic allergies
Injections of dilute amounts of allergen are given to “modulate” the pets immune system.
This is the only method that does not involve immuno-suppression
May take 6 to 9 months to see a dramatic response
Very individualistic treatment, (dosage, frequency, etc)
About 65 to 75% of patients respond well
Many patients may still need adjunctive therapy during high allergen seasons
Very well tolerate, although reactions are rare they can occur
Antirejection medication used to decrease the immune response
Well tolerated, but some pets can vomit
Omega 3 fatty acids
Omega 3 fatty acids may result in inflammatory mediators
Help to regulate replication of the epithelial cells
Help maintain moisture in the skin and follicles, preventing dry skin
May be more beneficial when used in combination with other therapy
Many available, many different responses
Effective for mild cases in some patients (maybe 30%)
May help reduce the dosage of other medications (corticosteroids)
Few side effects
Delivers medication locally, less chance of systemic side effects
Help reduce allergen on the patient
Control bacterial and yeast overgrowth
Soothes the skin
Help control oily or dry skin
Allergies can be a frustrating and difficult condition to control. There is no “Silver Bullet”, so set realistic goals. Pets will not be cured of this condition, only controlled! While everyone would like their allergic pet to itch no more than a normal dog, flare-ups are going to occur. This is no different than an asthmatic person. Therapy will be designed to keep your pet as comfortable as possible. No single therapy is effective in every patient.
Canine Atopic Dermatitis
□ Age at onset <3
□ Mostly indoor
□ Corticosteroid-responsive pruritis
□ Chronic/recurrent yeast infections
□ Affected front feet
□ Affected ear pinna
□ Non-affected ear margins
□ Non-affected dorso-lumbar area
This validated checklist is 85% sensitive and 79% specific when dogs meet at least 5 of the 8 criteria.* It is important to invstigate and rule out alternative or concurrent diagnoses based on the clinical findings.
*FavrotC., etal Vet Dermatology 2010