My Pet Won't Stop Itching - October 2013

By Dr. Samantha Ryan

Allergic Dermatitis (Inflammatory skin disease caused by any type of allergy) is a very common condition that can affect many breeds and mixed breeds.  Allergic Dermatitis causes itching and subsequent inflammation. Some allergies are thought to also have a genetic predisposition and may be passed down from parents to offspring.  Most dogs will develop allergy symptoms between 1 and 4 years of age.

Simply stated, an allergy is a reaction to an allergen, which is a substance that is capable of inducing a hypersensitive reaction in humans and animals.   Depending on the cause, the allergy event may be short lived or become a life-long condition.    An allergen can be almost any substance such as grass, pollen, flea saliva, dust or even a topical allergen such as different types of fabric.  The allergens will enter the body via inhalation, ingestion, parasites or touch.  Pets can also have more than one allergy that is present at the same time.  These factors can make the diagnosis and management of allergic dermatitis very challenging.

The most common symptoms of allergies are scratching, licking at the paws, rubbing the face, or watery eyes.  When pets scratch, they can cause secondary infections, excessive shedding and hairloss.  Other symptoms of allergies can include welts, sores and even ear infections.  Since these symptoms can be seen with other medical conditions, it is important to see the veterinarian to obtain an accurate treatment plan and diagnosis.

There are four main types of allergies that include atopy, flea allergy dermatitis, contact dermatitis and food sensitivities. Atopy occurs when your pet inhales airborne particles that stimulate an allergic reaction.  Unlike humans, a pet’s response is not to sneeze. Instead, they show reactions in their skin.  They typically chew at their feet, scratch at their skin and develop ear infections.

The second type of allergic response is flea allergy dermatitis.  Pets with FAD are allergic to the parasites’ saliva.  Hair loss, itching and a secondary skin infection are often seen with this type of allergy.   The most common location for the clinical symptoms are over the neck, back and back area of the thighs.

The third type of allergic disease is contact dermatitis.  This is a rare cause of itching in dogs and cats.  Clinical signs are often seen only where the offending allergen contacts the skin.  They are most likely to occur in thinly haired areas of the body, such as the inguinal region.

Food sensitivities are the fourth type of allergic response that can affect dogs and cats.  This is an adverse reaction to a food or an additive in the food source.  These symptoms generally will show up in younger patients.  The itching is nonseasonal and it may or may not respond to common medications that may be chosen to treat other forms of allergies.  Some animals will also have concurrent gastrointestinal signs such as vomiting or diarrhea.

Treatment of allergies will often involve a combination of therapies to best manage your pet’s clinical symptoms.  Shampooing can help relieve the itch temporarily, and can help remove scabs, scales, bacteria and other causes of itching.  Other topical medications that contain hydrocortisone can also be effective.  Anti-histamines and other oral medications may be recommended for some pets suffering from allergies. 

In conclusion, atopic dermatitis is a condition that is controlled and rarely cured, so the aim is to find a treatment that is effective and sustainable, with minimal side effects.  Often various trials and combinations of treatments are necessary before a combination of treatments is found that works for an individual pet.  Sometimes the opinion of a veterinary dermatologist will also be utilized if the pet’s clinical symptoms are not able to be managed or require advanced diagnostic evaluation such as intradermal skin testing.