Skin Allergies in Dogs
Food Allergy, Atopy and Flea Allergy All Cause Itchy Skin for Dogs
Apr 1, 2009
Skin problems in dogs are a common occurrence and are quite often the result of allergies. The most common causes of itchiness and hair loss in dogs are:
- Atopy (an allergic response to an inhaled substance)
- Flea allergy dermatitis (caused by flea saliva)
- Food allergy
- Secondary yeast or bacterial infections resulting from skin allergies
Symptoms of Skin Allergies in Dogs
Dogs suffering with skin allergies from any cause can be quite uncomfortable and even painful. Symptoms expected are:
- Itchiness expressed by rubbing, licking, scratching, biting or chewing at the skin
- Inflamed skin
- Hair loss
- Sores on the skin
- Thickening of the skin
Secondary bacterial infection may cause a discharge to be present from the skin as well.
Diagnosis of Skin Allergies in Dogs
Diagnosing dogs with allergies can be difficult. Common diagnostic tests used by veterinarians to diagnose skin disease are:
- skin scrapings, looking for mites and other parasites
- skin cytology, looking for evidence of bacterial or yeast infections
- blood screens (complete blood count, serum chemical profiles, possibly thyroid testing), looking for signs of systemic disease such as hypothyroidism and Cushing's disease
- fungal cultures, often used to diagnose fungal infections such as ringworm
- skin biopsies, which allow your veterinarian to better examine the architecture, cell make-up and abnormal changes in the affected skin
- therapeutic food trials, to help rule in or rule out food allergies
- therapeutic drug trials, often using medications effective in controlling fleas and/or killing mites and other parasites
- allergy tests, either skin testing or with a blood sample, to help determine what allergies your dog has
Treatment of Dogs with Skin Allergies
Treatment will depend to some extent on the results of specific testing once testing has been performed.
Options for symptomatic relief of skin allergies in dogs include:
- steroids, such as prednisone or dexamethasone. Note that these can have significant side effects and should be avoided if possible.
- antihistimines, such as Benadryl, Tavist, Atarax and Chlor-Trimeton.
- fatty acid supplements
- cyclosporine (Atopica)
- various shampoos, topical lotions and gels
- dips such as Lime Sulfur
- antibiotics to relieve secondary bacterial infections
- anti-fungal medications to relieve secondary yeast infections
The Role of Fleas in Skin Allergies in Dogs
Effective flea control is an important part of treating any dog with skin allergies as flea allergy is one the most common allergies seen. Just because you do not see live adult fleas on your dog does not mean that fleas are not the cause of the skin allergy. Dogs can be very efficient at removing fleas, especially when they are grooming excessively. In addition, there is a substance within the saliva of the flea which causes the flea allergy in dogs. So, one flea bite is all that is necessary to cause or sustain a skin allergy reaction.
Even if your dog truly does not have fleas, flea prevention is an absolute must because if your dog gets fleas, they will definitely influence the allergic reaction within the skin, making the skin allergy much more difficult to control for your dog.
Specific Treatments for Atopy in Dogs
Canine atopy requires allergy testing, either through skin or blood tests, in order to determine what allergens (allergy-causing substances) affect your dog.
Specific treatments for allergy involves either:
- avoidance of allergens, where possible
- immunotherapy or hyposensitization (often called "allergy shots")
- symptomatic relief
Treatment for Food Allergy in Dogs
Food allergies are usually treated by feeding specialized foods which are less likely to cause your dog's skin to have an allergic reaction to the food. These are referred to as hypo-allergenic diets.
Hypo-allergenic diets contain unique, novel proteins which most dogs are unlikely to have been exposed to in the past. At one time, proteins such as lamb were considered novel but as pet food manufacturers started producing foods containing lamb and rice, these foods have become less useful.
If possible, obtaining a history of all diets which your dog has eaten in the past can be useful. Choosing a food which contains ingredients your dog has never eaten before is more likely to result in a successful outcome.
Another alternative to novel protein diets are hydrolyzed diets. Hydrolyzed diets contain proteins which have been broken into very small pieces in the manufacturing process for the food. The theory is that these smaller hydrolyzed protein fragments are too small to be recognized by the body as an allergen and are thus less likely to cause an immune response leading to skin lesions.
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