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Learning how to deal with a challenging condition

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01 July 2009, at 12:00am

JENNA MARYNIAK reports on a seminar on the diagnosis and treatment of atopic dermatitis

IN April, Dr Tim Nuttall kicked off a roadshow of evening seminars on the diagnosis and treatment of atopic dermatitis, in Bromsgrove. 

Hosted by Novartis Animal Health, the seminars provided veterinary surgeons with an opportunity to benefit from his wealth of experience. 

The seminars included an hour’s lecture, information on the use of Atopica (Novartis) as part of the treatment regimen and an hour of practical diagnosis, using photographs, test results and information from cases referred to Dr Nuttall’s clinic. 

Dr Nuttall has a PhD in the immunopathogenesis of canine atopic dermatitis, is a member of the International Task Force on Canine Atopic Dermatitis and a senior lecturer in veterinary dermatology at the University of Liverpool. 

With his colleague Neil McEwan, he runs a busy dermatology referral clinic while continuing research on atopic dermatitis and microbial infections. 

The condition 

Over the years, atopic dermatitis has shifted from being seen as principally an allergic disease, then as an inflammatory disease and, more recently, a disease of the skin barrier. 

He explained that there is growing evidence that atopic skin has a poor epidermal lipid layer compared to normal skin. 

This may increase transepidermal water loss and exposure to irritants, allergens and micro-organisms. Self trauma then further decreases the epidermal barrier and exposes it to secondary infections with Malassezia and staphylococci. 

Age of onset is usually between one and three years old. Dogs are most often presented with pruritus and erythema, with other lesions developing later. Saliva staining, alopecia, papules, scaling and crusting, hyperpigmentation and lichenification are other common clinical signs. 

Other causes of pruritus, such as hypersensitivities (cutaneous adverse food reactions, flea allergic dermatitis, etc.), parasitic infestations, infections and other causes such as epitheliotropic t-cell lymphoma and immune-mediated diseases, need to be identified and ruled out or treated. 

Dr Nuttall explained that atopic dermatitis often exhibits peaks and troughs, but the severity of the disease slowly increases over time – making it important to diagnose and manage as soon as possible. 

He suggests that the aim of treatment is to get the symptoms into remission, and then keep the dog comfortable with on-going maintenance therapy. Short-term exacerbations can be managed with more aggressive treatment as and when they arise. 

He also stressed the importance of explaining to owners of atopic animals that the aim of treatment is not cure, but long-term management. He did acknowledge, however, that owner compliance is one of the most challenging aspects of this disease. 

“I will see better compliance rates because by the time they see me at the referral practice they have invested more time, effort and money and are often desperate for a resolution.” 

Dr Nuttall described the flare factors of atopic dermatitis, which include secondary infections, stress and environmental factors, such as central heating in autumn, pollens in spring, and heat and humidity in the summer. Treatment regimens involve identification of individual causes and flare factors, and will often require a multifaceted approach. 

Treatment options

Diet trials can eliminate food allergy as a cause, although this only affects 10% of atopic cases, but diet is also important in healthy skin function. Essential fatty acids have been shown to have some efficacy in atopic animals (leading to a 20 to 50% improvement). There is also published evidence that Eukanuba Dermatosis FP and Royal Canin Skin Support can help ameliorate canine atopic dermatitis to the same degree. 

Allergen avoidance may be possible, although avoiding ubiquitous allergens such as house dust mites can be difficult and there is little evidence that this is of benefit. Allergen specific immunotherapy (ASIT) is often used by Dr Nuttall and his team as it can be effective and is well tolerated. 

Bathing and hydration of the skin can also be useful, although he recommends that this should be done at least once a week, as the effect is shortlived. Bathing can also be timeconsuming and result in compliance problems. 

Topical anti-inflammatory treatment with glucocorticoids or tacrolimus (not licensed for animals) can also be very effective for lesions in hairless areas. Hydrocortisone aceponate (Cortavance) is also effective in more generalised atopic dermatitis, but may not be suitable for all cases. 

Well tolerated 

Dr Nuttall frequently recommends ciclosporin (Atopica) as a highly effective and well-tolerated option for anti-inflammatory maintenance treatment and as an alternative to longterm systemic glucocorticoid therapy. 

It has been proven to be very effective for canine atopic dermatitis and can be used as a monotherapy in cases where a simple treatment is necessary or where compliance is a problem. It is particularly useful in managing chronic atopic dermatitis with severe inflammation and lichenification. 

The first effects are usually seen within two weeks although the full response may take four to six weeks. Once in remission, either the dose or frequency should be decreased for maintenance. 

Treatment is likely to be life-long, and he warned of the tendency for owners to want to stop treatment completely once symptoms have subsided. He said it can be harder to achieve remission again after a relapse, and nurse clinics and follow-up support can help achieve compliance. 

Although glucocorticoids should be used long-term only as a last resort, short courses of 0.5-1.0mg/kg prednisolone once daily for three to seven days are useful for crisis management and to produce rapid remission at the beginning of treatment. 

Agnès Delauche, senior brand manager at Novartis, said: “The feedback from the seminars has convinced us that atopic dermatitis is a condition that vets often find challenging in everyday practice. 

“The condition can cause a huge amount of distress to owners and can be difficult to treat and retain good client compliance, particularly if the problem is not diagnosed and managed effectively straight away. 

“We know from our market research that more than half of owners of atopic dogs visit at least two vets in search of a solution for their dog’s disease. 

“This indicates the importance of their pet’s well-being and the risk for vets to lose clients.”