GEOFF ORBELL
The onset of spring often coincides with an increased number of dogs, cats and horses presenting with pruritus and secondary skin and ear infections due to atopic dermatitis or feline atopic skin syndrome (FASS).
The diagnosis of atopic dermatitis is based on history, clinical presentation and ruling out other causes of pruritus including external parasites, secondary infections, contact allergy and food allergy. Once a diagnosis of atopic dermatitis has been made, then immunotherapy may be considered as part of the long-term management. Immunotherapy is formulated for an individual based on the results of an allergy test which can be with either an intradermal skin test or a serum allergy test. The majority of cats, dogs and horses will respond favourably to immunotherapy including at least a 50% reduction in pruritus, secondary skin and ear infections and medications needed i.e. anti-pruritic and antimicrobial.
The response rate to immunotherapy does not appear to vary according to the type of allergy test performed. Intradermal testing is a referral procedure as dermatologists are trained in the interpretation of the reactions. Serum allergy testing is often utilised in addition to intradermal allergy testing by dermatologists and may be preferred in some cases.
Serum allergy testing could be considered in cases where clients are interested in immunotherapy and:
> Referral to a dermatologist for intradermal skin testing is not an option e.g. due to location
> Clipping the coat is not desirable, e.g. show animals
> Sedation is contraindicated due to increased risk from concurrent disease/conditions e.g. brachycephalic dogs.
Gribbles Veterinary currently offer the Heska ALLERCEPT® IgE serum allergy test as a highly specific serological test, based on 48 Australasian environmental allergens including pollens from grasses, weeds and trees, insects and moulds.
Requirements of sampling include:
– A minimum of 2mL of blood in a serum tube (sent on ice)
– Patients should be exhibiting clinical signs at the time of sampling
Serum allergy tests are considered to be less affected by drugs than intradermal allergy tests, but the following guidelines are recommended:
= Oral short-acting glucocorticoids at anti-inflammatory doses for less than 2 months; no withdrawal needed.
= Oral short-acting glucocorticoids at higher doses or for more than 2 months; 4–6-week withdrawal
= Injectable long-acting glucocorticoids; 28 day withdrawal
= Topical short-acting glucocorticoids (skin, ear and eye medications); no withdrawal needed.
= Topical long-acting glucocorticoids (e.g. sustained release ear medications);14-day withdrawal
= Cyclosporine when administered for less than 2 months; no withdrawal needed
= Oclacitinib (Apoquel®), lokivetmab (Cytopoint®), antihistamines, NSAIDs, essential fatty acids; no withdrawal needed.
Results are usually available within 3 weeks and do not include an interpretation, therefore consultation with a veterinary dermatologist is recommended. Several veterinary dermatologists within New Zealand are able to formulate and dispense immunotherapy.
Awanui Veterinary is able to send a copy of the Heska ALLERCEPT® results to a specified veterinary dermatologist on request.
References
> Mueller RS. A systematic review of allergen immunotherapy, a successful therapy for canine atopic dermatitis and feline atopic skin syndrome. J Am Vet Med Assoc. 261: S30-S35, 2023.
> Outerbridge CA, Jordan TJM. Current Knowledge on Canine Atopic Dermatitis: Pathogenesis and Treatment. Adv Small Anim Care. 2:101-115, 2021.
> Santoro D et al. Clinical signs and diagnosis of feline atopic syndrome: detailed guidelines for a correct diagnosis. Vet Dermatol. 32: 26-e6, 2021.
> Marsella R et al. Equine allergic skin diseases: Clinical consensus guidelines of the World Association for Veterinary Dermatology. Vet Dermatol. 34:175-208, 2023.
> Olivry T & Saridomichelakis M. Evidence-based guidelines for anti-allergic drug withdrawal times before allergen-specific intradermal testing and IgE serological tests in dogs for the International Taskforce on Allergic Diseases of Animals (ICADA). Veterinary Dermatol. 24: 225-e49, 2013.