Atopy or Atopic Dermatitis is one of the most common forms of allergic skin disease in dogs. Like human allergies, it is brought on by seasonal pollen and other airborne allergens.
However, while humans tend to get hay fever, dogs present with itchy skin or ear problems.
Affected animals persistently scratch, lick and bite to get relief. Constant scratching can lead to sores, hair loss and secondary infections.
Cats can suffer from allergic dermatitis, too, often hiding to constantly scratch and groom. Respiratory symptoms (runny nose, watery eyes or coughing, sneezing and wheezing) may also be seen in cats.
Management of the disease can be difficult and usually requires lifelong therapy.
What is atopy?
Atopic or allergic dermatitis is caused by sensitivity to allergens in the environment, such as dust mites, mould spores or tree, grass and weed pollens. Diet can also affect the condition. In the allergic state, the animal's immune system 'overreacts' to foreign substances (allergens) to which it is exposed, resulting in itchiness, either localised (in one or several areas) or generalised (all over the dog).
Many of these allergies occur seasonally, just as in humans, and get worse each year with additional allergen exposure, so early treatment is vital. It is thought to be a genetically inherited disease seen in all breeds of dogs, although Bull Terriers, Boxers, Dalmatians, Retrievers and West Highland Terriers seem to be at higher risk.
What are the signs of atopy?
Atopy is most commonly seen for the first time in dogs 6 months to 3 years of age, and initially may be associated with the 'pollen' season, although symptoms are constantly present in older dogs.
Inflammation of the skin produces severe itching, usually generalised. The dog chews, licks, and scratches its skin, resulting in hair loss and secondary infections. The problem may be worse in the axillae (armpits) and underside of the abdomen. Some dogs mainly chew their feet. Saliva will stain light coloured hair, so dogs that lick excessively will have reddish brown areas on their coat.
Rubbing of the face is also a common sign, as are inflamed ears and recurrent ear infections.
Seborrhoea is the overproduction of sebum by inflamed skin. It gives the coat an oily feel and a musty, strong smell. Bacteria thrive in sebum and this also contributes to the odour.
In cats, you may see red, bumpy skin, hair loss, inflammation, skin tearing on the head and neck, and sometimes respiratory symptoms like a runny nose, sneezing or wheezing.
How is atopy diagnosed?
Diagnosing atopic dermatitis is based on exclusion of other disorder with similar signs, such as Flea allergy dermatitis (FAD), Scabies (caused by burrowing mites), food allergy or bacterial and fungal skin infections.
Blood tests can be taken to confirm allergic dermatitis and indicate which allergens are causing the problem. A more reliable method is skin testing. Small amounts of the allergen are injected into the skin to see if an allergic reaction occurs at the site. A skin specialist usually performs this procedure.
How is atopy treated?
There is no cure for atopic dermatitis, but there are many treatment options. Avoidance of the offending allergen is the most effective form of control of the disease but this is often impossible.
Treatment may include a combination of the following.
Cortisone is a potent anti-inflammatory and therefore quickly lessens redness, swelling, and itchiness. If cortisone is appropriate for your dog, you will be given precise instructions for giving them. Follow the written instructions to decrease the incidence of side effects. Side effects are usually only seen with long-term and/or high dose usage.
Antihistamines are also anti-inflammatory and since they do not have the side effects associated with cortisone, are often trialled for chronic atopy patients. They are not effective in some cases, but can significantly decrease the amount of cortisone needed to provide relief. Sometimes up to 3 different antihistamines are trialled to see if any are effective.
Fatty acids are often supplemented, as these are also anti-inflammatory. Combinations of omega-3 and omega-6 fatty acids are used as dietary supplements.
Antibiotics and antifungal drugs
Secondary bacterial and/or fungal infections are common as a result of self-trauma to the skin. Deep infections may require up to 2 months of antibiotics. Skin infections are themselves itchy, so compound the problem.
Medicated shampoos may be required for secondary bacterial and/or fungal infections. Otherwise hypoallergenic, soothing shampoos containing oatmeal and aloe vera are often beneficial. Your vet can advise you on the most appropriate shampoo for your dog's skin.
After testing identifies the specific allergens responsible for your dog's atopy, an injection can be made incorporating very small amounts of the antigen. The purpose of this therapy is to reprogram the body's immune system. As time passes, the immune system becomes less reactive to the problem allergens. Hyposensitisation benefits the majority of dogs, reducing the amount of other therapy required. However, since new allergies can develop over time, retesting may be required if the dog relapses.
A specifically developed medication for atopy is available from veterinarians (Atopica). It targets the immune cells involved in the allergic reaction, providing long-term control of the allergic response in a dog's skin. This medication has been proven in extensive trials to be very effective and well tolerated. It may also reduce the need for add-on medications. This treatment may be given lifelong if necessary. Atopica for Cats has just been released in Australia. Ask your veterinarian for more details.
The most important contributor to successful long-term management is following your veterinarian's advice, and ensuring medication is always given on time. It can be tempting to stop treatment when symptoms improve but, without treatment, symptoms will almost certainly recur.
It can be difficult to avoid pollens but if your pet is allergic to house dust mites you can wash your pet's bedding regularly, wash soft furnishings regularly, vacuum frequently with a high efficiency particle air (HEPA) filter cleaner, use air dehydration and purification systems and use insecticides effective against house dust mites.
It is also a good idea to maintain rigorous flea control at all times. Flea bites may cause a flare up, particularly if your dog is allergic to flea bites.
If your pet is showing symptoms of constant scratching or grooming, rubbing its face and ears or chewing its feet, please see your vet before the condition becomes harder to manage, nasty infections set in and your pet becomes just plain miserable.