Most dogs will sit on their rump and have a scratch behind their ears or relieve an itch on the trunk of their body. They will then stand up, shake off, and continue on with their day. A dog with atopic dermatitis will spend the majority of their waking hours scratching themselves, nibbling on their paws, licking their skin, and/or rubbing their face.
This constant licking, nibbling and scratching indicates an itchy, itchy skin. This persistent itch – or pruritis – is very uncomfortable for the dog, but it can also be disruptive, especially if the dog sleeps near you at night. Dogs with atopy are commonly awake at intervals throughout the night to continue itching and scratching… and they don’t do it quietly!
In this article, we explore the signs and symptoms of atopic dermatitis, how it’s diagnosed and what can be done to bring relief to a dog with itchy skin.
What is atopic dermatitis?
Canine atopic dermatitis is a skin disease characterised by severe itch, which is triggered by allergens in the environment. Those allergens could include grass, dust, pollen, mites, mould spores or even detergent used to wash the dog’s bedding. When spores or other allergens are inhaled or come into contact with the dog’s skin, they trigger an immune response resulting in inflammation (the ‘–itis’ in ‘dermatitis’) and the excessive itchiness of atopy. The itch is severe, causing the dog to scratch persistently, often resulting in self-mutilation. Despite wounding themselves, they continue to scratch, introducing bacteria into their skin, which can lead to secondary infection.
Up to 15% of dogs can have atopic dermatitis, with the onset of the disease occurring between the ages of six months and three years. Some dogs only experience a few annoying symptoms like a recurring ear infection, while other dogs experience a severe, persistent itch in the folds of their skin (in the groin and armpits), on their chest and belly, and on their muzzle and around their eyes. It is pervasive, and their owners will seek veterinary help when the itch becomes disruptive or when their scratching causes a secondary bacterial or fungal infection (when bacteria or fungi are introduced into broken skin that was damaged by their scratching).
What causes canine atopic dermatitis?
It is generally accepted that there is a genetic component to canine atopic dermatitis – that certain dogs have a genetic predisposition to become allergic to everyday allergens in their local environment. It may not be the breed itself, but the gene pool of the breed in a particular location.
When healthy dogs come into contact with pollens, dust, mites, mould spores, etc., their immune systems eliminate them without becoming reactive to these allergens. However, the immune systems of dogs with atopic dermatitis are hypersensitive to environmental allergens and the dogs become extremely itchy as a result of exposure to them. It’s difficult to pinpoint exactly which allergen is responsible for their itch, and in many cases, there are multiple allergens that all have the same effect because the dog’s immune system is so reactive.
Another aspect to atopic dermatitis is that the dog’s skin barrier can be defective. As a function of their immune system, their skin is supposed to prevent allergens from entering the body. However, when dust, mites, pollen, or any other environmental allergens come into contact with their skin, they penetrate the faulty skin barrier, and trigger an over-the-top immune response, which includes inflammation and redness, as well as the characteristic never-ending itch.
Sometimes, atopy can be caused by a flea bite (with the allergen being flea saliva) or a food protein, which triggers the immune system via the digestive tract. What foods cause atopic dermatitis in dogs? Proteins like beef, dairy, chicken, eggs, grains, soy, corn, pork, fish or lamb can be potential triggers, so removing them from the dog’s diet can reduce the symptoms. This does not ‘cure’ the atopic dermatitis, it just removes the trigger.
What are the symptoms of canine atopic dermatitis?
Owners of dogs with atopic dermatitis will notice the onset of symptoms in dogs between the ages of six months and three years old. Some may be allergic from as young as two months old, and some may only develop allergies at six years old, but rarely after seven years.
There is a period of sensitisation to the environmental allergens before their immune system becomes over-reactive to them, which is why puppies can appear healthy at first. However, when the immune system is triggered, it can cause symptoms such as:
- itching
- redness and inflammation of the skin
- persistent scratching, licking and nibbling or chewing at the skin
- rubbing the face and ears with paws
- shaking the head
- rubbing the face on hard surfaces
- hyperpigmentation (darkening of the skin)
- ear infections
- secondary infection (bacterial and fungal)
- scabbing
- hair loss
- GI problems like diarrhoea and vomiting
Areas of the body that are most affected by itching:
- paws
- webbing between the toes
- armpits
- groin
- face and ears
- abdomen
A small percentage of dogs will also develop upper respiratory symptoms such as inflammation in the nose (rhinitis) and airways (asthma). Some dogs with canine atopic dermatitis will only develop recurring ear infections, with few or none of the other symptoms.
How is atopic dermatitis in dogs diagnosed?
There is no single diagnostic test for canine atopic dermatitis. The vet will need a lot of information from the dog owner before they can even start eliminating what the problem is not, before they make the diagnosis of atopic dermatitis. The vet will need information such as: when the itching (or any other primary symptom) started, how long it’s persisted, what other behaviour presents, where on the body the owner first noticed a problem, how often the dog is bathed, whether previous treatment has been sought and how the dog responded to it. The vet will also want to know whether the owner has other pets and if this problem scratching or ear infection is limited to just their one dog. Has the dog’s environment changed? Is stress a factor to consider? Has the dog travelled in the last year? They will also ask about the dog’s diet in order to eliminate a food allergy, which also presents with itchy skin.
With as much information as the dog owner can give them, the vet will then begin to exclude or eliminate every other cause of the dog’s itchy skin – called a differential diagnosis. They may do skin scrapings or smears to check for/rule out the presence of mites and other ectoparasites. Tests and treatments for fleas and skin mites that do not prevent the itch will exclude ectoparasites as the cause. The vet will then exclude bacterial and fungal causes, allergic skin diseases like flea allergy dermatitis, contact dermatitis and food allergies, as well as skin cancer.
It will take more than one vet visit to reach the diagnosis, but atopic dermatitis is a complex disease and the vet will want to exclude every other possibility before pursuing the management of this difficult condition.
How to treat atopic dermatitis in dogs
Owners of dogs with this condition will undoubtedly ask: how long does it take for atopic dermatitis to go away? Unfortunately, atopic dermatitis cannot be cured – it can only be managed for the purpose of improving the dog’s quality of life. There might be days when it’s under control and there may be other days when even the slightest exposure to the allergen causes a flare up. The successful management of such a pervasive disease requires a close cooperation between dog owner and veterinarian. The vet will suggest and recommend everything they can to preserve the dog’s comfort, but it requires the owner’s compliance with at-home treatment. This may involve accurately administering the dog’s medication, reducing the dog’s exposure to the triggering allergens, and taking measures to support their skin barrier.
So how do you treat atopic dermatitis in dogs? When the vet first sees a dog with atopy, it’s likely going to be a poor pet who’s very flared up with red, scratched skin, hair loss and/or ear infection. Considering there are multiple factors at play in the cause and onset of atopic dermatitis, the treatment is multimodal as well. This is known as combination therapy.
The first thing the vet will need to do is bring the itching under control, which is quickly and easily done with corticosteroids. A short course of prednisone/prednisolone will be prescribed to bring some relief to the itchy dog. It acts by suppressing the dog’s immune system so that it does not over-react to environmental triggers. Unfortunately, a suppressed immune system may make the dog susceptible to other infections. Dogs who are on long-term corticosteroids need frequent vet check-ups to monitor their weight, rule out skin infections and make sure the dog is not suffering from urinary tract infections, which are a common side-effect of chronic use of corticosteroids.
To avoid the long-term use of corticosteroids, the vet may recommend the use of antihistamines to suppress the itch and inflammatory responses in dogs with atopic dermatitis. There are also medications that inhibit signals in the immune system, which ‘switch off’ the inflammatory and itch responses. These include:
- Oclacitinib – sold under the name Apoquel, which is an oral medication administered daily. It doesn’t address the root cause of atopic dermatitis, it targets and blocks the primary symptoms, which are itching and inflammation.
- Lokivetmab – this is an injectable monoclonal antibody under the name Cytopoint, which blocks the immune system’s response to the IL-31 protein that triggers itching. It’s administered every four to six weeks.
The vet may recommend Apoquel or Cytopoint depending on the severity of the atopic dermatitis, the dog’s age, location, and biology.
The vet will then recommend ways for the owner to ensure the dog can avoid allergen exposure as much as possible. If allergy testing is possible, the vet may be able to pinpoint which allergens are triggering the dog’s itching and then recommend ways to avoid them, such as:
- Prevent or limit exposure to grass by taking them for walks on the road, wearing booties, or opting for paving instead of lawn at home.
- Limit exposure to pollen by keeping the dog inside at peak pollen times (midday and early afternoon) and only walking them at the time of day when the pollen count is the lowest.
- Wiping the dog down and washing their paws every time they come inside, to prevent them from bringing allergens from outside inside, and reducing the allergen load, especially in the area where they sleep.
- Limit exposure to dust and mites by keeping the home clean and dust-free, decluttering, and frequently washing the dog’s bedding and blankets. If the vet is able to ascertain mites as an allergen, the dog must be kept away from bedding and fabric furniture, which is where mites would normally be concentrated. Regularly steam clean and vacuum carpets (or remove them altogether) and keep the dog in a carpet-free room.
- Limit exposure to mould spores by ensuring the home is properly ventilated, walls and linens are cleaned with bleach, and there are only a few or no house plants.
What do you feed a dog with atopic dermatitis? The vet may recommend a hypoallergenic dog food that supports the skin and immune system. They may also recommend the use of supplements that increase the intake of omega-3 and -6 fatty acids, which can help to repair and support the defective skin barrier and for their anti-inflammatory effect. Many dogs with atopy respond well to a healthy skin diet, but this alone will not be sufficient treatment for atopy. At this point, it’s not uncommon for dog owners to ask: Is coconut oil good for dogs with atopic dermatitis? Coconut oil applied twice daily as a topical treatment may help to soothe dry, itchy skin, but it doesn’t work for all dogs – it may even exacerbate skin conditions like secondary yeast infections. Dogs love the taste of coconut oil, so applying it to their skin may encourage them to lick it off. This is not constructive for dogs with atopic dermatitis, where it’s in the dog’s best interest not to become obsessive about licking their skin.
Other topical treatment involves medicated and barrier-restoring shampoos, hypoallergenic baths with oatmeal, skin sprays containing topical lipids and/or other natural ingredients, as well as corticosteroid spray.
Many dogs with atopic dermatitis will develop secondary infections, so it’s important to keep these under control as part of this treatment. Antibiotics (for bacterial skin infection) and antifungal treatment (for fungal infections like Malassezia dermatitis) combined with the use of an antimicrobial shampoo during weekly or biweekly baths will be helpful.
Long-term treatment of atopic dermatitis will involve all of the above, while the vet implements allergen-specific immunotherapy (ASIT). This involves performing a test to see which allergens affect the dog and then developing a vaccine protocol specific to that animal. It exposes the dog’s immune system to the allergen in gradual amounts to desensitise it so that the dog is less allergic to and more tolerant of environmental allergens. ASIT requires the dog owner to administer injections or oral drops over the long term (it is often life-long) and to carefully monitor symptoms. Immunotherapy can take up to a year to be effective, and has a 65 – 75% success rate. It still requires the dog owner to treat the symptoms, especially if they have seasonal flare-ups. ASIT is not a cure-all, but rather one method of reducing exposure to the allergens so that the dog is less reactive and less reliant on other therapies.
Can dogs grow out of atopic dermatitis?
Unfortunately, atopic dermatitis in dogs is systemic disease that involves the dog’s whole body – the skin barrier, the immune system, and microbiome. It does not simply go away or get better with age. It is a complex condition that is difficult to manage because of the many variables involved in the dog’s body and their environment.
The constant itchiness that characterises atopy is stressful for the dog, which can also lead to behavioural changes. It can make dogs irritable and/or anxious, and can affect their socialisation and training, as well as other areas of their quality of life. Atopic dermatitis is a challenging condition to address, so it will be in the dog’s best interest for the owner and veterinarian to work together to find the best solution for the dog’s wellbeing.