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Canine Atopic Dermatitis

By

Sandra Diaz

, DVM, MS, DACVD, The Ohio State University

Last full review/revision Aug 2020 | Content last modified Sep 2020
Topic Resources

Atopic dermatitis is characterized by chronic pruritis and a typical distribution of skins lesions. It is generally associated with IgE antibodies to environmental allergens to which susceptible animals are genetically predisposed to become sensitized. Diagnosis is based on clinical signs, history, and exclusion of other causes of pruritis. Treatment includes medications and baths that relieve pruritis and avoidance of allergens.

Clinical Findings of Canine Atopic Dermatitis

Multiple breeds have been shown to be predisposed to canine atopic dermatitis (AD), but the prevalence within a breed largely depends on the genetic pool and region. Breeds predisposed to development of AD include:

  • Chinese Shar-Pei

  • Wirehaired Fox Terrier

  • Golden Retriever

  • Labrador Retriever

  • Dalmatian

  • Boxer

  • Boston Terrier

  • Lhasa Apso

  • Scottish Terrier

  • Shih Tzu

  • West Highland White Terrier

The age of onset is generally between 6 months and 3 years. There is no sex predisposition.

Clinical signs may be seasonal, nonseasonal, or nonseasonal with seasonal flares. Pruritus is the characteristic sign of AD. The feet, face, ears, flexural surfaces of the front legs, axillae, and abdomen are the most frequently affected areas, but lesion distribution can vary with the breed. Primary lesions are uncommon and consist of erythematous macules, patches, and small papules. Most lesions develop secondary to self-trauma and are due to the presence of secondary infections. they include alopecia, erythema, scaling, hemorrhagic crusts, excoriations, lichenification, and hyperpigmentation.

Secondary skin and ear infections with Staphylococcus and Malassezia spp are common and often worsen the clinical signs. Chronic or recurrent otitis may be the only complaint in a small number of animals.

Diagnosis of Canine Atopic Dermatitis

  • Based on clinical signs, history, and exclusion of other causes of pruritis

Diagnosis of canine atopic dermatitis is challenging and is based on signalment, clinical signs, history, and the exclusion of other pruritic skin diseases (see differential diagnoses below), not on laboratory tests. Prospective studies have revealed the following clinical features compatible with a diagnosis of AD, known as Favrot's criteria:

  • affected ear pinnae (but not pinnal margins)

  • affected front paws

  • age of onset <3years

  • chronic or recurrent yeast infections

  • corticosteroid-responsive pruritus

  • mostly indoor lifestyle

  • nonaffected dorsolumbar area

  • pruritus without skin lesions at onset

The sensitivity and specificity of these set of diagnostic criteria are reported to be 85% and 79%, respectively. These criteria do not apply to cases of food-induced atopic dermatitis. Canine atopic dermatitis is very likely if at least five of the above criteria are present and other differential diagnoses have been ruled out.

Allergy testing (intradermal or serologic) is a diagnostic aid that measures increased levels of tissue-bound or circulating IgE; alone, it is not diagnostic but rather reflects exposure. The primary reason to pursue intradermal or serologic allergy testing is to identify the offending allergens in an individual animal and to formulate allergen-specific immunotherapy. Test results are significant only if the offending allergens identified are compatible with the history or seasonality of pruritus.

The most important differential diagnoses for pruritic skin conditions include:

Treatment of Canine Atopic Dermatitis

  • Medications and baths that relieve pruritis and avoidance of allergens

Atopic dermatitis cannot be cured, but the disease can in most cases be managed to improve quality of life of patients and owners. Client education is important, because this is a lifelong disease that requires lifelong management and regular progress checks. Management options depend on the severity of the clinical signs and whether the pruritus is seasonal or year round.

Avoidance of allergens: This may be the best choice, but it is difficult, if not impossible, to do unless a specific allergen can be identified.

Relief from pruritus: By definition, this is a pruritic skin disease; itching may be relieved via antipruritic drugs alone while waiting for allergen-specific immunotherapy (ASIT) to be effective, or in combination with ASIT in partially responsive cases (see below).

Bathing: Bathing dogs with AD may decrease pruritus. Bathing can reduce allergen load and can be the most effective way to implement avoidance. Weekly to biweekly baths are recommended. In dogs with a history of flares due to microbial overgrowth, routine use of antimicrobial shampoos may help decrease the incidence of secondary infections. Matching the active ingredients with the most likely problem seen adds extra benefit: eg, in cases of superficial pyoderma, the use of an antibacterial product like chlorhexidine will likely give the best results.

Recognition and control of flare factors: A relapse of clinical signs in a dog that is otherwise well controlled should prompt an investigation into what caused the exacerbation of pruritus. Recognized flare factors include, but are not limited to, fleas, food and environmental allergens, and secondary infections such as Malassezia dermatitis, superficial pyoderma, and otitis. These need to be investigated and addressed, and the level of pruritus must be re-evaluated before choosing longterm antipruritic therapy.

In acute flares:

  • Review and, if needed, implement flea control

  • Determine whether there is an increase in allergen counts

  • Identify and address secondary skin and ear infections

Table
icon

Select Therapeutic Agents for Atopic Dermatitis

Active Ingredient

Dosage

Key Points

Topical Glucocorticoids

Triamcinolone acetonide 0.015 %

Topically every 12–24 hours

Indicated for acute flares and localized lesions

Best suited for short-term use (7–14 days); adverse effects include cutaneous atrophy and calcinosis cutis

Hydrocortisone aceponate

Topically every 12–24 hours

Betamethasone valerate

Topically every 12–24 hours

Mometasone furoate

Topically every 12–24 hours

Oral Glucocorticoids

Prednisone/prednisolone

Induction or initial dose: 0.5–1 mg/kg, PO, every 24 hours

target dose after tapering: 0.25–0.5 mg/kg, PO, every 48 hours

Indicated for acute flares

Fast acting

Broad, nonspecific anti-inflammatory response

Many potential adverse effects

Calcineurin Inhibitors

Cyclosporine

Initial dose: 5 mg/kg, PO, every 24 hours; tapered to the lowest dose that controls the disease

Indicated for longterm management

Can take 4–6 weeks to achieve clinical improvement

Not suitable for treatment of acute flares

Most common adverse effects are GI signs

Indicated for localized lesions

Appears to be safe for short-term use

Tacrolimus 0.1 % cream

Topically every 12–24 hours

Prostaglandin E1 Analogs

Misoprostol

5 mcg/kg, PO, every 8 hours

Modest efficacy

Phosphodiesterase inhibitors

Pentoxifylline

10 mg/kg, PO, every 12 hours, or 20 mg/kg, PO, every 8 hours

May be best suited as adjunctive therapy for chronic conditions

Slow onset of action (4–6 weeks)

Not suited for acute flares

Good safety profile

Antihistamines

Fexofenadine

18 mg/kg, PO, every 24 hours

Helpful for mild pruritus

Best as part of combination therapy

Preventive role

Sparing agents for glucocorticoids

Not suitable for acute flares

Hydroxyzine

2 mg/kg, PO, every 12 hours

Hydroxyzine + chlorpheniramine

(20.9 mg + 0.7 mg)/10 kg (divided), PO, every 12 hours

Cetirizine

0.5–1 mg/kg, PO, every 12 hours

Essential Fatty Acids

High-quality fish oil (with EPA and DHA)

300 mg/4.5 kg, PO, every 24 hours

No current evidence of superior efficacy of any particular combination, dosage, ratio, or formulation to improve skin and coat quality and reduce pruritus

Janus Kinase Inhibitors

Oclacitinib maleate

0.4–0.6 mg/kg, PO, every 12 hours for 2 weeks, then every 24 hours

Indicated for acute flares and longterm management

Fast onset of action (within 24 hours) for pruritus control

Most common adverse effects are GI signs

Contraindicated in dogs with serious infections or neoplasia

May increase susceptibility to infections, demodicosis, and neoplastic conditions

Monoclonal Antibodies

Lokivetmab

2 mg/kg, SC, every 2–8 weeks

Indicated for acute flares and longterm management

Fast onset of action (1–3 days) for pruritus control

Most common adverse effects are lethargy and vomiting

Allergen Immunotherapy

Subcutaneous allergen-specific immunotherapy (SCIT)

Various protocols exist; adjust dosage and schedule for each patient

Very specific targeted effect

Slow onset of action (up to 12 months)

Not useful for acute flares

Most common adverse reaction is worsening of pruritus

Oral immunotherapy (SLIT)

Pump dispenser directly onto oral mucosa, between the lip and the gum, every 12 hours

Most common adverse reactions are face rubbing, transient worsening of pruritus, and GI signs

Adapted from Sandra Koch. What is new in the diagnosis and management of canine atopic dermatitis. Today’s Veterinary Practice. May/June 2015: 95–102.

Immunotherapy

Allergen-specific immunotherapy is the only treatment that can change a patient's immune response to allergens and induce remission of clinical signs. It remains the treatment of choice of most dermatologists and allergists. ASIT attempts to increase an animal’s tolerance to environmental allergens by inducing the development of anti-inflammatory cytokines, such as IL-10. IL-10 has been has been associated with production of IgG and decreased IgE levels. In people with AD, early administration of ASIT prevents progression of the disease.

ASIT consists of the administration of increasing doses of the offending allergens until a maintenance dose is reached. ASIT can be administered via injections or orally, which are equally effective; therefore, clients should choose a method based on the ease of administration.

For injectable ASIT, the interval between maintenance dosages varies with different protocols. Adjustments in the interval are based on the animal’s response and may vary from a few days to 3–4 weeks; for oral ASIT, the administration is once or twice a day. Owners are advised not to expect much response for 6 months and are asked to commit to at least 1 year of therapy before deciding the usefulness of immunotherapy. The best assessment of response is to compare the degree of disease or discomfort between similar seasons.

Side effects are uncommon; increased pruritus is the most commonly reported one. Most of these cases respond to premedication with an antihistamine, but some require dose adjustment. Less common side effects include pain at the injection site, urticaria, lethargy, and, very rarely, anaphylaxis. Owners should be asked to administer ASIT when able to monitor their animals for at least 30 minutes after administration. Owner education is very important when initiating ASIT. The need to perform the treatment for at least 12 months before evaluating the response, the best route of administration, the protocol, and the rate of success should be discussed in detail. The success rate of ASIT is approximately 66%, and some patients may require additional therapies such as regular bathing, essential fatty acids, and antihistamines.

Key Points

  • Atopic dermatitis is a genetically predisposed chronic inflammatory and pruritic allergic skin disease with characteristic clinical features.

  • Diagnosis is based on clinical signs, history, and exclusion of other causes of pruritis.

  • Management includes medications and baths that relieve pruritis and avoidance of allergens.

  • Client education and monitoring are key for treatment success.

For More Information

  • Olivry T, deBoer DJ, Favrot C, et al. Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA), BMC Veterinary Research, 2015, 11:210.

  • Also see pet health content regarding dermatitis and dermatologic problems in dogs.

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