Dog Skin Allergies & Itching

Besides ear infections, a skin-related allergy in dogs is the most common type of medical complaint that veterinarians see on a daily basis. A dog's skin allergy is a hypersensitive reaction of the skin due to an allergy-causing molecule or substance called an "allergen" or "antigen." When a dog ingests, inhales or comes in physical contact with an allergen, its immune system produces a protein called "IgE." This protein attaches itself to tissue mast cells located in the skin. This attachment causes various irritating chemicals (such as histamine) to be released in the skin, which causes the dog to itch.

  1. Diagnosing

    • One way veterinarians can diagnose the cause of a skin allergy is to perform a blood test, which analyzes more than 60 types of allergens. However, these tests are not always accurate because they were initially designed for human antibodies and can create many false positives. A more accurate allergy test is intradermal skin testing, which involves sedating your dog, shaving a small patch of hair on its side and injecting a specific antigen into its skin. The skin is then monitored for 2 to 5 days for a reaction. This is repeated until a dog reacts to a specific allergen. According to PetEducation.com, this method has a success rate as high as 75 percent.

    Atopy (Inhalant)

    • The most common cause of skin allergies in dogs is atopy (also known as atopic dermatitis or allergic inhalant dermatitis). This is an itchy skin disease that develops when a dog inhales an allergen that its immune system is particularly sensitive to and reacts to such as pollen, mold or house dust. There are several treatment options to consider with your veterinarian, which include Cortispray, immunotherapy allergy shots, antihistamines (such as Benadryl) and omega-3 fatty acids found in fish oils. If none of these treatments work, you may want to consider using a steroid such as cortisone in a low dose.

    Flea Allergies

    • Another major cause of skin allergies in dogs is fleas. Dogs are not allergic to the flea itself but to the proteins found in flea saliva, which is released into the skin when a flea bites a dog. Interestingly, dogs that are not constantly exposed to fleas are more likely to have a skin-related allergy reaction to a flea bite. The best form of treatment is to follow a strict flea regime, which usually involves administering a monthly topical ointment such as Advantage or Frontline to the skin on the neck of your dog.

    Food Allergies

    • Your dog may develop food sensitivity to a certain ingredient in his food such as beef, pork, milk, chicken, fish, corn or soy. The most common side effect will be itching. Also, it is not uncommon for a dog to develop an allergy to a food that it has been eating for years because allergies can develop over time for unknown reasons. The best way to find the ingredient your dog is allergic to is to give your dog a homemade diet consisting of a protein and a starch that it has never eaten. Next, each week add a single ingredient, such as corn, and observe your dog for any type of reaction. You need to continue this time-consuming process until you find the ingredient causing the skin allergy. About 10 percent of dog skin allergies are caused by foods.

    Other Causes for Itching Besides Allergies

    • Dog itching can also be caused by several other conditions and diseases besides skin allergies. Examples of such conditions and diseases are mange, cancer, bacterial infections, behavioral problems and drug or injection reaction. Further, some dog breeds inherit certain rare medical conditions that can cause itching. For example, miniature schnauzers can have a condition called schnauzer comedo syndrome, which causes comedones (black heads) to form in the skin, resulting in itching and thinning of the hair.