Allergy testing and Immunotherapy (desensitisation)
Immunotherapy (desensitisation) is used in atopic dermatitis with the aim of eliminating or minimising the need for immunosuppressive drugs. These drugs can have serious medium term side effects.
Small doses of allergens identified by skin testing are given at regular intervals to "retrain" the immune system so as not to "over-react" to common allergens such as grasses, weeds, pollen, insects, moulds and dust mites.
Immunotherapy has a good success rate in dogs, cats and horses. Multiple studies have shown that about 65-70% of patients will improve by at least 50%. This reduces their suffering and dependence on immunosuppressive drugs
Dr Rob performs intradermal skin testing to identify the allergens needed to make an immunotherapy vaccine. This requires sedation as at least 60+ allergens are tested for.
Withdrawal periods of drugs prior to Intradermal testing
Depot corticosteroid injections 6-8 weeks minimum (longer the better)
Potent topical corticosteroids (dexamethasone, betametasone and mometasone , including ear drops, 10-14 days
Hydrocortisone topicals and antihistamines 7 days
Cytopoint (lokivetmab) Nil
Apoquel (oclacitinib) 4 days
Intradermal skin testing is regarded by Veterinary Dermatologists as the "Gold Standard" for testing. There are various blood tests available but they vary in correlation with the results from skin testing. The results from any laboratory also offering blood tests for food allery should be treated with suspicion. A recent study in Australian dogs has shown higher numbers of blood test positives in NORMAL non-atopic West Highland White terriers than in the atopic group! BEWARE of companies offering saliva or hair testing. A recent study showed no ability to detect differences between normal dogs, allergic dogs and synthetic fur!
A recent study (ESVD Congress 2013) comparing four major laboratories in the US with respect to serum allergy testing found little better correlation and agreement between labs on the same samples than would be expected by chance.
This is not to say all blood tests for allergen determination are useless.
The testing laboratory must use the most specific method and produce repeatable results
The results should be interpreted in the light of the patient's signs and seasonality and the vaccine formulated knowing about laaergen cross reactions.
Treatment of canine atopic dermatitis: 2010 clinical practice guidelines from the International Task Force on Canine Atopic Dermatitis (see LINKS)
The ACVD task force on canine atopic dermatitis (XVII): intradermal testing.