Dogs can develop itchy or inflamed skin for a number of reasons. Common culprits include fleas and flea allergies, food allergies, environmental allergies, and bacterial or yeast infections. Infections are often secondary to damaged skin; for example, recurrent ear infections may suggest an underlying allergy. A less common cause of very intense itching is sarcoptic mange (scabies); sarcoptic mange is caused by a mite and is highly contagious to other dogs and people. In all cases, persistent or recurrent itchiness or skin disease should be evaluated by a veterinary dermatologist. Rarely, persistent skin disease is a symptom of a more serious underlying disease including autoimmune disease, cancer, or organ dysfunction.
Fleas and Mites:
Flea bites can cause significant itching, as can an allergic reaction to the flea’s saliva. Therefore, dogs with only one or a few fleas can develop itchy skin from an allergic reaction that may mirror the severity of itchiness in dogs with a heavier flea infestation. In addition to itchy skin, fleas can transmit diseases. Fleas may be obvious in some cases but can be hard to find on other pets. They often congregate on and around their hind legs and at the tail base. If you are worried your pet may have fleas or want to learn more about options for flea prevention, you can discuss fleas with your primary care veterinarian.
Just like people, dogs may be allergic to things in their environment, including dust, dust mites, and pollen from numerous different plants. These allergies may be year-round or seasonal. Dogs with environmental allergies may benefit from allergy testing and management with a dermatologist, to determine if specific medications or topical treatments are indicated.
Dogs can be allergic to certain food ingredients, including beef, chicken, and dairy. Like environmental allergies, food allergies may manifest as persistently itchy skin or recurrent skin or ear infections. In most cases, a food trial is needed to prove or disprove a food allergy. Hypoallergenic or novel protein diets may be prescribed by your veterinarian. Importantly, your dog must ONLY receive the prescribed diet during a food trial, as even one treat containing an allergen could set off the allergy and confound results of the food trial.
Secondary bacterial or yeast infections can cause significant itching in dogs. The skin has its own normal population of bacteria, but opportunistic infections may occur if the skin is damaged or compromised in some way. Licking, scratching, or allergic disease can predispose to infections; areas of the skin that are trapped under skin folds are also more prone to infection. Acute skin infections may improve with antibiotics, medicated shampoos, and topical treatments.
Importantly, dogs must not be permitted to continue to scratch or lick affected areas, as this could delay or prevent improvement. Dogs with chronic or recurrent skin infections- including recurrent ear infections- often benefit from additional testing and treatment recommendations by a veterinary dermatologist. In some cases, cultures or biopsies of the skin and allergy testing are indicated.