What is atopy or atopic dermatitis of dogs?

It’s worth starting with the fact that atopy and atopic dermatitis are not exactly the same thing, at least not in humans.

Atopy is the general name of the entire condition and atopic dermatitis is the umbrella term for its manifestations at skin level. Besides skin issues, people also get atopy-related respiratory symptoms (like hay fever or asthma), but these almost never happen in dogs, so their atopic dermatitis is the main and often the only way in which their atopy reveals itself, hence the interchangeability of the terms when speaking about dogs.

So, what is canine atopy? It is an allergic condition or hypersensitivity that some dogs (approx. 1 in 10) have to allergens in their environment.

This predisposition towards a ‘trigger-happy’ immune system, and therefore atopy and allergies in general is inherited. For example, atopic dogs often have flea allergies or food allergies at the same time.

The age at which dogs get diagnosed with atopy varies a lot, from 6 months to 6 years old, with the highest percentage between 1-3 years old. Dogs over 7 years are unlikely to develop atopy. There’s no difference between sexes, male and female dogs get atopy at the same rate.

The risk of developing atopy is higher in Basset Hounds, Beagles, Bichon Frises, Boxers, all types of Bulldogs, Bull Mastiffs, Bull Terriers, Cairn Terriers, Chow Chows, Dalmatians, Fox Terriers, German Shepherd Dogs, Golden Retrievers, Great Danes, Hungarian Vizslas, Jack Russell Terriers, Labradors (especially chocolate-coloured ones), Lhasa Apsos, Newfoundlands, Pugs, Rhodesian Ridgebacks, Schnauzers, Shar-Peis, Shih Tzus, Springer Spaniels, Staffordshire Terriers, Tibetan Terriers and (last, but not least!) West Highland White Terriers.

What is most likely to trigger atopic dermatitis in dogs?

The most common atopy-related allergens that come to mind are grasses and pollen, but in fact the list is much longer and not restricted to outdoor things, unfortunately. Dog with atopy can be allergic to:

GRASSES

• Meadow grass (Poa pratensis)

• Meadow fescue (Festuca elatior)

• Orchard grass (Dactylis glomerata)

• Perennial rye (Lolium perenne)

• Redtop (Agrostis alba)

• Sweet vernal (Anthoxanthum odoratum)

• Timothy grass (Phleum pratense)

WEEDS

• Dandelion (Taraxacum officinale)

• Dock (Rumex crispus)

• Lamb's quarters (Chenopodium album)

• Mugwort (Artemisia vulgaris)

• Nettle (Urtica dioica)

• Ox-eye daisy (Chrysanthemum leucanthemum)

• Plantain (Plantago lanceolata)

• Ragweed (Ambrosia artemisiifolia)

• Red clover (Trifolium pratense)

TREES & SHRUBS

• Alder (Alnus serrulata)

• Ash (Fraxinus americana)

• Beech (Fagus grandifolia)

• Birch (Betula populifolia)

• Hazelnut (Corylus americana)

• Oak (Quercus rubra)

• Privet (Ligustrum vulgare)

• Willow (Salix nigra)

The plant allergens can be either the plant’s pollen or the proteins in its cells which are released when the plant cells are crushed (as when the grass is cut, for example).

STORAGE MITES

• Acarus siro

• Lepidoglyphus destructor

HOUSE DUST MITES

• Dermatophagoides farinae

• Dermatophagoides pteronyssinus

DANDER

• cat epithelia

• human epithelia (yes, sadly, your dog can become allergic to you!)

MOULDS

• Alternaria type (Alternaria tenuis)

• Aspergillus mix (A. amstelodami, A. flavus, A. fumigatus, A. nidulans, A. niger)

• Penicillium mix (P. camembertii, P. chrysogenum, P. digitatum, P. chrysogenum, P. roquefortii)

Initially the allergens are breathed in and meet the respiratory immune system but later, as the allergy unravels the skin barrier, microbes and irritants can also come in contact with the immune system of the skin and make the symptoms worse.

What symptoms do dogs with atopic dermatitis have?

An allergic flare-up in dogs usually starts with an itch that can become very severe as the time passes.

Later you might see:

• skin redness, pimples, weepy or crusty areas,

• an oily coat and dandruff,

• patches of thinning coat or even complete baldness,

• thickening and darkening of the skin.

The areas where this is most obvious are the face, ears, armpits, lower belly, groin, paws and flanks.

Some dogs also get:

• lumps between their toes,

• frequent ear infections,

• weepy eyes.

When to call your vet

If you suspect that your dog may have atopy, it’s recommended to speak to a vet as soon as possible.

Allergies of any kind do not go away by themselves. With atopy, the produced antibodies can vary in concentrations depending on the time of the year and how much allergen is around, giving milder or worse allergic flare-ups. But overall these flare-ups only tend to get worse and happen at shorter and shorter intervals if nothing is done to control them.

How is dog atopic dermatitis diagnosed?

As described in the overview article on hypersensitivities, identifying allergies is done by excluding (or confirming) them one by one.

In order to correctly diagnose a dog with atopy, the vet will first exclude:

• non-allergic skin issues,

• flea allergic dermatitis with a test or an effective flea control,

• food allergies with a food trial.

Even though, as mentioned above, atopy is more common than food allergies in dogs, they often are seen together. Therefore, it is very helpful to exclude or minimise the food allergy’s contribution to the itchiness threshold before attempting to treat the atopy.

A thorough medical history will be taken and a complete exam of your dog done to determine if atopy is their (main) allergy type. This will be more likely if your dog:

• is under 3 years old,

• shows symptoms that vary in intensity with the time of the year,

• started itching first, then got rashes and other visible skin changes,

• doesn’t itch if given steroids,

• has symptoms on the front feet and ears, but not the lower back or the ear margins.

How is dog atopic dermatitis treated?

For dogs with mild symptoms and no other allergies, antipruritic medication can sometimes be sufficient for managing the seasonal worsening of their itchiness.

For dogs with bad symptoms, the treatment has a short-term and a long-term part.

In the short term the vet will also use medication to stop the itching and also anti-inflammatories and antibiotics to treat secondary skin infections and allow the skin to calm down and heal.

Long-term, the plan for these dogs usually starts with identifying what exactly is the dog allergic to, either by serological or intradermal skin testing.

For serological testing, a blood sample is taken from the dog and sent to the lab where they measure the concentrations of antibodies against the allergens listed at the beginning of the article. This is usually done at most vet practices.

The intradermal skin testing is similar to the one done in humans, on a patch of (shaved) skin a small quantity of different allergens is injected and the skin reaction to each is measured after a short period of time. Dogs obviously don’t sit willingly for this, so they need to be sedated for the test. Since the allergen solutions are not that easy to get, only dermatology specialists do this type of testing.

For the test results to be reliable the dogs have to be at least 12 months old and not have had any medication that influences the immune system within a certain period of time.

Allergen identification through testing is a very important step - it helps you keep your dog away from the allergens where possible and your vet determine which allergens should be included in their immunotherapy treatment.

Antigen-specific immunotherapy (ASIT) or simply ‘immunotherapy’ is one way of preventing future atopic flare-ups. Another option is using medications that either suppress the immunity temporarily or contain antibodies against the allergen-specific antibodies.

The best treatment plan for an atopic dog will depend on several factors (how bad are the symptoms, how many things is the dog allergic to, how well they respond to medication, etc), but immunotherapy is most often recommended by vets.

What can you do to help your atopic dog?

It may make you feel very helpless to see your dog itching badly, but there are many things you can do to help them:

• Keep a strict parasite control for all pets in your household. Even without a flea allergy on top of their atopy, flea bites, mites or other skin parasites can further irritate an atopic dog’s inflamed skin.

• Keep long-haired atopic dogs shortly clipped in the summer – it makes them easier to wash and they gather less allergen on the shorter coat.

• Support their skin barrier by bathing the entire dog or at least their paws after walks. Washing removes allergens and microbes from the skin, don’t replace it with wiping the dog down - this only spreads them over the coat. Use antiseptic, soothing shampoos. Dry the dog thoroughly after.

• Remember the indoor allergens (dust and storage mites) - remove rugs where possible, vacuum and mop as often as possible, use HEPA filters, wash bedding and toys at 60°C if possible, seal in vacuum bags and freeze for 72 hours what’s not washable.

• If your dog doesn’t have food allergies as well, use skin supporting foods and supplements.

Atopy can be incredibly frustrating for you to deal with. Don’t struggle with it on your own, FirstVet is here 24/7 so you can book an appointment with us at any time to speak to one of our vets about it!