5 Reasons Your Dog Itches: Starting from Scratch

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Many trips to the animal hospital begin with a pet owner’s observation of scratching.

Between skin allergies and skin infections, scratching is the most common complaint that brings dogs to veterinary clinics4—and with good reason. When a dog is licking, biting and clawing until the skin is visibly broken, it points to an underlying problem that will require medical attention.

Below are five leading causes of itching that afflict dogs and disrupt household life.

1. Flea allergy dermatitis

Flea allergies are usually everyone’s first suspect when we see a dog scratching, even if it’s for no particular reason. While your home may be free of fleas, your dog can still pick up fleas outside the home. Whatever the source, your dog can be driven half crazy by itching, hair loss and scabs caused by flea infestation.

Repeated exposure can lead to abnormal, excessive reactions to even a single flea bite, making it extra hard for a veterinarian to pinpoint the cause. These hypersensitivities often lead to infections and inflammation. Your veterinarian will explain treatments and preventives—with emphasis on prevention.

2. Atopic dermatitis

Caused by a collision of each dog’s particular genetics and environment, atopic dermatitis is one of the most common categories of allergic dermatitis in dogs. Simply stated, atopy is a steroid-responsive itch that isn’t caused by anything with legs, anything that can be grown in a laboratory or anything dogs eat. Atopic dermatitis can be triggered by direct contact with molds, dust or pollen, but the condition is really caused by an inappropriate immune reaction rather than by the allergens themselves.

Dogs afflicted with atopic dermatitis periodically lick and chew at their paws and scratch their face, eyelids and ears. Treatments vary, but most involve avoiding the allergens, treating the condition with medications that have fewer side effects than steroids, or desensitizing your dog by injecting small quantities of allergens to adjust the immune system responses.

3. Food allergies

Dogs can have food allergies just like people, but their reactions may be different, including chewing, scratching or rubbing, which cause secondary infections from bacteria, yeast (see below) or fungus. Food allergies may also result in hair loss, vomiting and diarrhea.

Your veterinarian may recommend a strict temporary diet to isolate which foods your dog is allergic to, followed by a long-term diet to avoid the allergenic ingredient. The initial trial may take several weeks and require your careful attention to detail, but it’s just as important as any prescribed medication.

4. Yeast skin infection

Yeast are a normal inhabitant of the skin and ears—in low numbers. But sometimes they can overgrow and cause infection, resulting in itching, red or flaky skin or a pungent odor. It appears that increased warmth and humidity of the skin raise the odds of a yeast infection, especially under your dog’s skin folds and in the ear canals. Yeast skin infections can be treated with certain medicated shampoos or oral medications.

5. Bacterial infection

Bacterial skin infections can occur secondary to an allergic condition listed here or be the primary cause of the itching. Common strains of bacteria include Staphylococcus pseudintermedius, Staphylococcus canis and others. Common signs include moist, sticky, inflamed skin lesions and hair loss.

Any injury or damage to intact skin will weaken the skin’s defense mechanisms. Naturally occurring surface bacteria are thrown out of balance or penetrate the skin via cuts or inflammation. This leads to chewing and scratching, causing more kinks in the skin’s armor and letting more bacteria through the skin, which continues the vicious cycle.

The treatment for bacterial skin infections may start with clipping hair from the infected areas to allow drying. Topical therapy may also be helpful, including cleansing, antiparasitic and medicated shampoos. Antibiotics are especially effective in treating a bacterial infection when administered in full compliance with the veterinarian’s prescription. Because taking pills several times a day may be stressful for you and your pet, oral antibiotics administered once a day or an injection that lasts up to two weeks may offer a better chance for successful treatment.

The early identification of the cause of your dog’s itching —with appropriate treatment and prevention— can increase not only your pet's comfort, but also the quality of life for your whole family.

IMPORTANT SAFETY INFORMATION: People with known hypersensitivity to penicillin or cephalosporins should avoid exposure to CONVENIA. Do not use in dogs or cats with a history of allergic reactions to penicillins or cephalosporins. Side effects for both dogs and cats include vomiting, diarrhea, decreased appetite/anorexia and lethargy. See full Prescribing Information.

4 Veterinary Pet Insurance Co. Top 10 reasons pets visit vets. Available at: http://www.petinsurance.com/healthzone/pet-articles/pet-health/Top-10-Reasons-Pets-Visit-Vets.aspx. Accessed May 13, 2014. (The top reason listed was skin allergies, while skin infection ranked fourth.)

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