Skin Problems

 

Atopic dermatitis (atopy) is a condition where the dog is allergic to common environmental allergens such as pollens, moulds and dust mites. This condition often becomes apparent in the first 1-3 years of life and is characterised by seasonal or non-seasonal itching, scratching and chewing of multiple body parts. Saliva staining is often observed in the areas most affected, e.g. feet and groin. The ears are a continuation of the skin so ear infections are also very common in dogs with atopic dermatitis. Self trauma such as scratching and licking causes inflammation and the skin becomes prone to secondary infections with bacteria and yeast. In chronic (long term) disease the skin may become hairless, thickened, scaly and black. The coat may also feel greasy and have an offensive odour.

 

It is important to rule out any other causes of itchiness before assuming the cause is atopy. These include flea allergies, food allergies, infection, contact allergies, other parasitic infections and possible hormonal imbalances. These causes also often complicate atopic dermatitis, needing identification and treatment before any underlying atopy can be recognised. It is important to be aware that atopic dermatitis is a life long condition that often requires management with continuous treatment by a committed and motivated owner.

 

Methods of diagnosis

• Food allergy is an uncommon cause of allergic skin disease, but if identified is easy to treat long term and the dog can live an easy itch-free life without the use of any drugs! A food allergy trial (elimination diet) is the method used to identify any food allergies. The dog should be fed a diet consisting of a completely novel (new) protein for at least 8 to 12 weeks and nothing else. In some dogs food allergy may coexist with other allergies, so a full or partial response may be noted. Home made diets that are best for trials must contain both a novel protein that your dog has not eaten before (e.g. kangaroo, venison) and a carbohydrate (e.g. sweet potato). This home cooked diet is not fully balanced so if your dog improves on the new diet we will consult with you to determine the best balanced hypo-allergenic diet for long term use. Commercial hypo-allergenic diets can be fed as a sole food source as it is a complete balanced diet.

 

• Intra-dermal skin testing allows us to diagnose atopy and identify specific allergens (environmental substances that the dog is allergic to). Once identified, allergen avoidance may be the best and easiest treatment, but in most cases dogs are allergic to multiple allergens, or they are unavoidable (e.g. dust mites). In these cases we are able to create an allergy vaccine for life long treatment.

 

• Allergen specific immuno-therapy (ASIT) involves injecting doses of specific allergens over a period of time. This is to help reduce the immune system “over reaction” so that the dog no longer reacts to the environmental stimulus to such an extent and is therefore less itchy. 70% of dogs have a good response and 25% can be controlled by ASIT alone, others need additional supportive treatment such as topical medication or antihistamines.

 

• Blood tests and skin biopsies are occasionally needed to determine if there are any underlying hormonal imbalances or problems that may be causing immuno-suppression or dermatitis.

 

Medical therapy:

• Cyclosporin - This is the first choice treatment for allergic dermatitis. It is often as effective and has mild and often reversible side effects when compared to corticosteroids. Resolution of itchiness is usually seen within 2-4 weeks. In many cases Cyclosporin can be used at a tapering dose to every other day or twice weekly and still maintain patient comfort and control of atopy.

 

• Prednisolone - This is a corticosteroid which suppresses the immune system, meaning it stops the immune system “over reacting” to allergens. It is not uncommon to trial corticosteroids (once infection has been ruled out) either as a diagnostic tool to see if there is a response, or as a control. Many dogs are well controlled on low dose Prednisolone, but this medication does have side effects such as increased appetite (and resultant weight gain) and increased thirst and urination.

 

• Antihistamines - These are commonly used in the management of allergic dermatitis, but are a lot less effective in dogs with success in only 10-20% of cases. Beneficial effects should be observed in the first 7-14 days of treatment and there are few side effects. Importantly, they are mostly used in conjunction with other treatments to help reduce the dose or frequency of other drugs e.g. corticosteroids.

 

• Essential Fatty Acids(EFAs) have been found to be beneficial in the management of atopy, specifically omega 3 and omega 6. EFAs help inhibit the inflammation process at the skin layer as well as improving the skin barrier. Omega 3 is present in fish oils while omega 6 is in evening primrose oil. There is a formulation available from vets that contain both omega 3&6. Adding these to the diet may help with symptoms and can be used in conjunction with any of the above treatments.

 

Topical medications:

• Shampoos – There are a wide range of medicated shampoos conditioners and washes. When infection is present we recommend a shampoo that has antibacterial and anti-fungal properties. If the skin is dry and itchy with no signs of infection then an oatmeal shampoo and conditioner is recommended as it helps to sooth the itch and moisturise dry flaky skin.

 

• Creams – Topical creams may also help sooth itchy skin. Most contain an antibiotic, an anti-fungal and a corticosteroid that works as a local anti-inflammatory without the systemic side effects. Applied to localised areas these can help reduce the inflammation and associated reaction.

 

• Sprays – There is a topical corticosteroid spray available that is also useful for small localised areas of inflammation.