As many of you have been following the progress of ‘Dexter’ the Scottish Wheaten Terrier on our FB page, this month we will be focusing our article on Canine Atopic Dermatitis (or Atopy) in the dog. Although we are still in the process of diagnosing the possible cause of his symptoms, Atopy is the most likely.
CANINE ATOPIC DERMATITIS (CAD ) – what is it?
CAD is one of the most common allergic skin conditions seen in dogs worldwide causing severe itching and inflammation. The Yorkshire terrier, Schnauzer, Boxer and Scottish Terriers are just some of the breeds that are genetically predisposed to this condition. Symptoms usually begin at an early age (6 mths – 3 years) compared to other skin conditions.
CAD is linked to the antibodies the body produces in response to environmental allergens. The skin, which is the bodys first line of defence, usually forms a strong barrier against potential allergens. In the allergic dog, the top layers of the skin are often defective, thus allowing absorption of these allergens.
What is it caused by?
‘Hay fever’ sufferers will know that they are usually not allergic to just one allergen but to many, for example, grass, pollen, dust mites, etc. CAD works in the same way, as there can be numerous allergens such as dust mites, pollens, mould spores, danders, insects, food etc all contributing to the cause. The diagram below may help you understand how the body reacts when over sensitised.
What are the symptoms?Primary Lesions:
- Constant scratching and biting of face, feet, ears, abdomen, causing areas of abnormal pigmentation
- Reddened and raised skin lesions
- Hair loss
- Bacterial infections
- Yeast and Fungal infections
- Ear infections
- Erosion of the skin due to scratching rubbing or biting
- Thickening and leathering of the skin
- Scabs and crusting
Clinical signs often occur seasonally but may be seen year-round as the condition persists.
How is it diagnosed?
Because of the complexity of this disease, diagnosis is extremely challenging .A good history and a full dermalogical examination is essential in recognising the first clinical signs of this condition. Your vet will need to determine:
- age, breed, sex and home environment of your pet
- the type and distribution of any lesions.
- presence of parasites and their contribution to the problem
- the possibility of a food allergy
- presence of any secondary infections
Your vet may need to take skin scrapings, a skin biopsy and swabs to test for parasites and secondary bacteria and yeasts.
“ Ultimately, the diagnosis of CAD is made based upon signalment, typical history, presentation of compatible clinical signs, and the systematic exclusion of all other pruritic skin diseases. There is no single test for CAD. It is a clinical diagnosis made by exclusion of other differentials.”(1)TREATMENT
“CAD cannot be cured. Client education is important, because this is a lifelong disease that requires lifelong management and regular progress checks.”(2)
Once your vet has an overall picture of the problem they will be able to establish a treatment protocol, which could include any if not all of the treatments below:
- effective treatment for external and internal parasites, like fleas and worms
- eliminate secondary bacterial and/or fungal infections
- bathing with hypoallergenic and medicated shampoos
- topical therapies, such as sprays and creams
- supponovel food trials
- Non-steroidal anti inflammatory drugs
- Constant assessment of the animal
“Is the practice of administering increasing quantities of an allergen extract to an allergic subject to ameliorate symptoms associated with subsequent exposure to the causative allergen”. (2)
Allergen specific immunotherapy (ASIT) is available but extremely costly. In this treatment the animal is slowly ‘desensitized’ to specific allergens that it has shown to be hypersensitive to. Firstly, intradermal and serum tests are undertaken in order to determine which allergens the animal is most sensitive to. Unfortunately these tests are not available in South Africa and samples must be sent overseas.
“The mechanism of action of ASIT is complex and not fully understood. Essentially, the pet is “desensitized” to specific allergens to which it has demonstrated hypersensitivity, and immune tolerance is induced. In dogs, the expected time to response is roughly 4-12 months”.(3)In Conclusion
Canine Atopic Dermatosis is a complex disease that requires lifelong treatment. There is no quick fix and owners need to understand that adherence to treatment protocol is of the utmost importance. As we have seen with Dexter, once an animal is diagnosed and the condition is treated consistently, it does not take long to see amazing results.
‘Successful management requires a basic understanding of the complexity of the disease, an accurate diagnosis, control of secondary problems, institution of a comprehensive management plan, and frequent reassessment.’(4)Further Reading:www.nevetdermatology.comwww.merckvetmanuel.comwww.nevetdermatology.comwww.nevetdermatology.com