Skin Allergies (Atopic Dermatitis)

Atopic dermatitis is a chronic, inflammatory skin condition caused by an abnormal immune response to environmental allergens - pollens, house dust mites, mould spores, and other substances in the environment. It is the second most common skin disease in dogs after flea allergy dermatitis, and it has a strong genetic component.

The defining sign is itching - often involving the face, paws, ears, armpits, and groin. Secondary bacterial and yeast skin infections are common because repeated scratching and licking breaks the skin barrier.

What to monitor

Itch severity. Score daily on a 0–10 scale: 0 is no itching, 10 is constant, severe itching that prevents sleep and normal activity. The CADESI (Canine Atopic Dermatitis Extent and Severity Index) is a formal scale; a simple personal score is sufficient for home logging.

Body areas affected. Note which parts of the body are worst - paws, ears, face, armpits, groin, belly. Different allergens tend to affect different distributions.

Ear status. Regular ear infections are one of the most consistent signs of underlying atopy. Note ear odour, discharge, head shaking, or scratching at ears.

Paw chewing. Persistent licking or chewing of the paws is a hallmark sign, often causing rust-coloured staining of white fur.

Skin changes. Redness, thickening, greasiness, hair loss, hyperpigmentation (darkening of skin) in affected areas. Describe what you see rather than interpreting it.

Seasonal pattern. Note which months are worst. Spring and summer (tree/grass pollen) and autumn (mould spores) are common peak seasons. Year-round disease often indicates house dust mite involvement.

Flare triggers. Note any association with specific environments, activities (swimming, long grass), new products (washing powder on bedding, new shampoo), or dietary changes.

Managing secondary infections

Repeated scratching and licking causes bacterial (usually Staphylococcus) and yeast (Malassezia) overgrowth. These infections cause significantly worse symptoms than the allergy alone and require treatment to resolve the flare. Log when infections appear - typically as increased redness, odour, and altered skin texture in affected areas.

Treatment options

Management of atopic dermatitis has improved considerably. Options include:

• Apoquel (oclacitinib) - oral JAK inhibitor; rapid relief, used daily for long-term control
• Cytopoint (lokivetmab) - injectable monoclonal antibody; given every 4–8 weeks by the vet
• Allergen-specific immunotherapy - allergy testing (intradermal or blood) followed by tailored desensitisation injections or drops; the only treatment that addresses the underlying cause
• Medicated shampoos - reduce allergen load on skin and manage secondary infections
• Omega-3 fatty acids - support the skin barrier; evidence for modest benefit
• Antihistamines - less effective in dogs than humans; may provide mild relief in some dogs

Log which treatments are being used and when, alongside the itch score. This is how you determine what's working.

When to contact your vet

Contact your vet promptly if:

• A skin infection has developed (increased redness, odour, crusting, pain)
• Current treatment is not providing adequate control
• A new area of skin is becoming affected

Schedule a routine appointment for:

• Initial diagnosis and treatment planning
• Allergy testing referral if allergens need to be identified
• Medication reviews

Frequently Asked Questions

How is atopic dermatitis diagnosed? Diagnosis is made by ruling out other causes of itching (fleas, food allergy, scabies, infections) - there is no single confirmatory test. Allergy testing identifies specific allergens but doesn't diagnose atopy itself; it's used to guide immunotherapy.

Is a food allergy the same as atopic dermatitis? No. Food allergies cause similar signs (itching, ear infections, skin changes) but involve a different immune mechanism triggered by food proteins rather than environmental allergens. They can coexist. A strict dietary elimination trial is needed to diagnose food allergy.

Can atopic dermatitis be cured? It cannot be cured, but it can be well-controlled with appropriate management. Allergen-specific immunotherapy offers the possibility of long-term improvement in allergen tolerance in some dogs.

My dog's itching is seasonal - does that mean it's not atopy? Seasonal patterns are typical of atopy caused by outdoor environmental allergens. Year-round disease often indicates house dust mite sensitivity (the most common allergen), but seasonal onset doesn't rule it out. Some dogs start seasonally and broaden to year-round over time as they become sensitised to additional allergens.

Should I change my dog's food if they have atopy? If food allergy is also suspected - based on year-round disease that doesn't respond to environmental allergen treatment - a dietary elimination trial is worth doing. But if your dog has seasonal itching consistent with environmental atopy, a food change alone is unlikely to resolve it.