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Itchy Skin in Dogs
by Eve Allely, BVSc
Persistent itchiness in dogs can be associated with a number of skin conditions, frequently with multiple triggers. Sometimes these have fairly obvious presentations, but commonly a diagnosis can only be reached by process of elimination. The following is a summary of the more common itchy skin conditions and diagnostic methods by which each can be recognized.
A dog’s response to a flea bite varies from a transient minor itch to a more distressing hypersensitivity (allergic) reaction. While a heavy flea burden is usually quite obvious, a flea bite hypersensitivity may be more subtle in that the offender/s often may not be seen. The simplest way to establish if fleas are the culprits is to eliminate them from the affected dog, any in-contact animals and environment with reliable flea treatments.
As the name suggests, an allergic reaction to food! Dogs can exhibit an allergy to completely new foods but also over time can develop an allergy to their existing diet. The most common allergy-inducing components in dog food are proteins - what can be fine for most dogs, can cause problems in certain individuals.
Image source wikimedia commons
The other potential offender is the carbohydrate component. The only way to establish food allergy as the cause of itchiness is to give the dog an elimination diet trial. This has to be for a minimum of six weeks and is based on a “novel” protein and carbohydrate. The dog is not allowed access to any other dog food, human food, other animal food (eg cat), treats or even milk during this time. Veterinary prescription diets provide the most reliable, balanced and easiest way of achieving this trial.
The most common of these we see is Malassezia, a surface opportunist. Most dogs harbour these organisms in low numbers but given the right conditions eg an underlying allergy they will overpopulate and contribute to the itchiness. They produce a distinctive odour and can be seen in samples taken from the skin surface under a microscope. Treatment options include medicated shampoos and antifungal tablets.
This refers to overpopulation with bacteria, again usually opportunistic in nature (with even more potential underlying causes eg allergies, immune disorders etc) They too can be seen in samples checked under the microscope and will also contribute to itchiness. Infections can vary markedly in severity, and treatment options range from medicated shampoo to antibiotic tablets (which often require prolonged courses.
A contagious mite that infects the skin of some wild animals and dogs (potentially humans but usually self-limiting unless host is immunocompromised).
Usually the clue in a dog’s history is previous exposure to other itchy dogs or wild vectors. More common in Australia where foxes act as vectors.
Hairless or sparsely-haired areas of dogs are vulnerable to this form of allergic dermatitis. There are several plant species that will affect most dogs in this way. Wandering Dew is our most commonly implicated offender.
Contact allergies can occur in response to many other things including blankets, carpets etc and dogs will vary in their sensitivities, most having no problems at all but others being very reactive. Diagnosis is made by patch testing suspected allergens.
Basically what you are left with once all other possibilities have been discounted! Atopy is one of our most common itchy skin conditions but the most difficult to deal with. Traditionally it was thought that the problem arises from inhalation of air-borne allergens eg dust mites and pollens. Dermatologists have now come to the conclusion that atopy is the outcome of defects in skin barrier function. It is often hereditary. Intradermal skin testing can be done to identify the most threatening allergens for certain dogs with the aim of formulation of a vaccine to gradually desensitize the patient (variable success)
Other means of dealing with this type of allergy are:
The important things in regards to itchy dogs are:
If your dog is itchy, don't delay, call us today!