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The important points, first
- The first sign is itching: the dog scratches, rubs, chews or licks too much, scoots or shakes its head.
- The most affected areas are the face, inner ear flaps, belly, armpits, groin, perineal area and lower legs and paws.
- It usually starts between 6 months and 3 years of age.
- No single test proves atopy. Fleas, other parasites, infections and, if itching lasts all year, food allergy must be ruled out first.
- Baths with a mild shampoo and year-round flea control are part of management. Fatty acids give at most a small benefit.
What atopic dermatitis is
The International Committee on Allergic Diseases of Animals (ICADA) describes canine atopic dermatitis as a common, inflammatory, itchy skin disease with a genetic predisposition. According to the Merck Veterinary Manual it can affect dogs of any breed, including mixed breeds, although some breeds are more predisposed, among them Labrador and Golden Retrievers, Boxers, West Highland White Terriers and Shih Tzus.
First signs usually appear between 6 months and 3 years. ICADA explains that itching may be seasonal, for example when pollen is the cause, or present all year, when dust mites or foods are involved.13
How it is recognised
The first sign is itching. The dog scratches, rubs, chews, licks too much, scoots along the floor or shakes its head. At first the skin may look normal or just red. The areas most often affected are the face, the inner surface of the ear flap, belly, armpits, groin, perineal area and lower legs and paws, with some differences between breeds.
Over time scratching leads to wounds, scabs, hair loss, scaling and skin and ear infections. Merck adds that in a few dogs recurrent ear infections are the only sign, and that about 15% of affected dogs also develop rhinitis or asthma. According to ICADA, bacterial and yeast infections of the skin and ears are a common cause of flares.132
Reaching a diagnosis
No test proves atopic dermatitis on its own. ICADA explains that diagnosis relies on clinical criteria and ruling out other causes of itching: fleas first, then other parasites such as sarcoptic mange, and skin infections. Your veterinarian may therefore suggest strict flea control, skin scrapings and cytology.
If itching lasts all year, or there are digestive signs too, an elimination diet is needed, followed strictly for at least 8 weeks. Blood or skin allergy tests are not used to make the diagnosis: the blood test is often positive in dogs that are not allergic. They are used afterwards, once the diagnosis is made, to choose the allergens for immunotherapy.12
Long-term management
Atopic dermatitis lasts a lifetime and needs regular check-ups. For ICADA the first step is recognising and avoiding what triggers flares, such as allergens, fleas and infections, together with good skin and coat hygiene and year-round flea control. Bathing at least weekly with a mild shampoo and lukewarm water is likely to help, and for itching the frequency and regularity of baths matter most. If the skin becomes dry or irritated, change the product with your veterinarian.
Oral essential fatty acids may give a small benefit, visible only after about two months, and are not enough on their own. Effective medicines exist for itching and lesions, chosen by your veterinarian. According to ICADA, allergen-specific immunotherapy is one of the few interventions that can prevent or delay flares; Merck warns that it may take 6 months to a year to tell whether it works.23
Sources and checks
Numbers in the text lead to the exact source. Commercial blogs and social posts are not used as evidence.
- 1Veterinary guideline
Canine atopic dermatitis: detailed guidelines for diagnosis and allergen identification
BMC Veterinary Research (2015), ICADA · PubMed PMID 26260508 · Seasonal or year-round itching, affected areas, ruling out parasites and infections, elimination diet of at least 8 weeks, allergy tests not diagnostic.
Link checked on 16 Sept 2026 - 2Veterinary guideline
Treatment of canine atopic dermatitis: 2015 updated guidelines from the International Committee on Allergic Diseases of Animals (ICADA)
BMC Veterinary Research (2015) · PubMed PMID 26276051 · Flare factors and infections, year-round flea control, bathing, fatty acids with limited benefit, immunotherapy among the interventions that prevent flares.
Link checked on 16 Sept 2026 - 3Peer-reviewed veterinary manual
Allergies in Dogs
Merck Veterinary Manual · Dog Owners · Age of onset, predisposed breeds, seasonality, secondary signs, ear infections and asthma, lifelong management and immunotherapy timing.
Link checked on 16 Sept 2026
This guide does not recommend medicines, supplements or doses and cannot diagnose an allergy. Persistent itching should be assessed by your veterinarian.