Allergy is a state of hypersensitivity in which exposure to a harmless substance known as an allergen induces the body’s immune system to “overreact.” Dogs usually manifest their allergies or hypersensitivities in the form of skin disease, as opposed to people who usually display symptoms of respiratory disease or “hay fever” (watery eyes, runny nose, sneezing). This will often present as the “itchy” patient or the patient with skin disease resulting from self-excoriation and secondary skin infections. The 3 most common allergens to affect canines are: flea allergy, airborne allergy (this will be referred to as “atopy” hereafter), and food allergy. Each of these will be discussed in further detail. Allergies to all of the above usually result in some form of itching, licking, or chewing of the skin. Skin allergies can be very difficult to manage, and even with the best care, many dogs will still experience some degree of itchiness. Unfortunately, we are not usually able to “cure” allergies and this is typically a life-long problem that your dog may experience in varying degrees throughout the year. Our goal is to control allergies as best as possible to improve the quality of life for you and your pet.
Canine Allergies
What are the major types of allergies that affect dogs?
Flea Allergy (Flea Allergy Dermatitis)
Flea allergy dermatitis or FAD is the most common allergy affecting both dogs and cats. Many animals have flea infestations with minimal to no skin disease, while animals with FAD can have profound skin disease with the presence of very few fleas. The allergy is caused by an individual patient’s hypersensitivity to the flea saliva and it only takes a few bites to induce the problem. For this reason, very regular flea control is essential to help keep FAD animals symptom-free. The itching and skin disease associated with flea allergy is most commonly distributed around the base of the tail, along the back, down the back legs and on the stomach. Hair loss or thinning is often present in those areas and the skin may be red, crusty and have red bumps called papules. The goal to prevent the itchiness associated with FAD is regular flea control. But, sometimes in order to control severe itchiness we may recommend oral steroids. This will depend on the severity of your dog’s current flare up.
I don’t understand…I never see fleas on my dog. How can the problem be flea related?
You may not see them, but that doesn’t mean they aren’t there. Due to our hot, humid climate, fleas are EVERYWHERE in Louisiana. Again, it only takes a few bites to induce the problem. One trip into a flea infested environment can result in several flea bites even in dogs that are on appropriate flea prevention. Also, the itchy pet often scratches and bites so much that adult fleas are removed, making them hard to find.
How often must flea prevention be given?
If you have a dog affected with FAD, then monthly, year-round prevention is essential to help control symptoms. We have both oral and topical preventatives available. Please ask a member of our staff for our best current recommendation.
Atopy or Airborne Allergy (Atopic Dermatitis)
Atopic dermatitis (AD) is an inherited predisposition to develop itchiness and skin disease from exposure to a variety of commonplace and otherwise harmless substances including dust, mold spores, and the pollens of weeds, grasses and trees. Symptoms may be seasonal in some patients, but the absence of a seasonal component does not rule out atopy as the cause of your dog’s itchiness. Diagnosis of AD is usually made on suspicion from the patient’s history, clinical presentation and response to treatment. A more specific diagnosis can be made using intradermal skin testing, but this is not available in most general vet practices and usually requires referral to a veterinary dermatologist. The vet will discuss this with you if he/she feels it is warranted. The skin disease and itchiness associated with atopy can exist on almost any part of the body but the following areas are most common: feet, face, lower chest or abdomen, arm pits, and ears. Affected areas may be red, crusty, have a thinned hair coat and may contain red bumps called papules. These skin changes are usually the result of self trauma from scratching, licking or chewing. Secondary infections with bacteria and/or yeast are very common. Ear infections also commonly accompany AD and some animals may have this as their sole manifestation of the allergy.
How can atopic dermatitis be managed?
Antihistamines (Benadryl, Chlorpheniramine, Zertec, etc.) are often used as a first line of defense. Unfortunately, antihistamines are often minimally effective against the itchiness that accompanies atopy. Because of their safety with long-term use, low degree of side effects, and accessibility, antihistamines are still often tried. The vet will speak with you about dosing options for your dog.
Steroids (Prednisone, Dexamethasone, DepoMedrol, etc) are usually very effective in controlling atopy but their use must be limited due to side effects, especially with long-term use. The most common side effects are increased thirst, increased urination, increased appetite, and panting. Steroids are an immunosuppressive medication and do increase the risk of acquiring infections. Long-term use is rarely advised as a control for atopy and owners must understand the possible risks. Most patients are started on a higher dose then tapered or decreased to a lower dose over time.
Reducing Exposure to the Allergen The following are general tips to avoid exposure that can be practiced; although, in the dog with moderate to severe atopy, even strict adherence to these guidelines may not resolve symptoms.
- Weekly baths to remove allergens from skin surface. Careful to avoid over bathing, as atopic dogs are subject to drying of the skin. There are many good OTC hydrating shampoos. Bathes and/or washing of the feet after prolonged trips outside may help.
- Wash bedding regularly. Vacuum regularly and keep pet away when dusting, vacuuming or cutting the grass.
- Use air conditioning and/or air filter system
Omega 3 Fatty Acid Supplementation may help to decrease the severity of symptoms or help to decrease the frequency of needed medication. These products are NOT analogous to adding oil to the pet’s food. There are many good OTC products available. It often takes 6 weeks to build up enough omega 3 fatty acids in the body to observe a difference.
Hyposensitization (Allergy Shots) These injections are available for canines, but formulation is based on intradermal skin testing, which currently requires referral to a veterinary dermatologist. The vet can speak with you more about this if you are interested.
Food Allergy (FA)
Some pets develop specific hypersensitivities to components of their diets. The allergen is usually a major protein or carbohydrate ingredient such as beef, chicken, pork, corn, wheat, or soy. Minor ingredients such as preservatives or dyes are also potential allergens. The skin disease and itchiness associated with FA can exist on almost any part of the body but these are most common: face, feet, lower abdomen, ears, and anus. Affected areas may be red, crusty, have a thinned hair coat and may contain red bumps called papules. These skin changes are usually the result of self trauma from scratching, licking or chewing. Secondary infections with bacteria and/or yeast are very common. Ear infections also commonly accompany FA and some animals may have this as their sole manifestation of the allergy.
How can food allergy be diagnosed?
A food trial is performed, which means that we test your pet by feeding a special, strict diet that contains only ingredients that the patient has never eaten before. This is often achieved by feeding a prescription diet for a period of 10 to 16 weeks. If the signs resolve after this period, a challenge is performed by feeding the former diet and watching for a return of the itching. If this occurs, a diagnosis of food allergy is confirmed. The vet can speak in more detail about these diets.
But my dog has been eating this food for a long time? Why now?
Many people assume that the itching due to FA requires a recent diet change, but the opposite is often true. FA takes time to develop; most animals have been eating the offending food for years with no trouble.
Combined Allergies
Some animals have multiple allergies. It would not be particularly unusual for an animal with atopy or food allergy to also be allergic to fleas, especially considering that flea bite allergy is extremely common among pets. Because allergies add to each other, it is possible that an atopic or food allergic dog will not itch as long as its fleas are controlled. This is why we will always stress the importance of flea preventative in any dog with allergic skin disease. Since new technology has made flea control safe and convenient, it is especially important to ensure that fleas are not complicating a pet’s itching problem.