Allergic Disease in Animals

At Coastal Veterinary Dermatology & Ear Clinic, we are very familiar with allergic disease in animals. Many of our four-legged family members suffer from allergies. In fact, 20% of the dogs in the U.S. have an underlying allergic disease. That's one out of every five pups! The most common sign of allergies in dogs and cats is itching, also called pruritus. This can be manifested as biting, chewing, licking, rubbing, or scratching. These patients may also have recurrent skin infections with bacteria and/or yeast, along with significant ear problems. In rare cases, you may even notice runny eyes, sneezing, or coughing. We will help you to manage the secondary infections on the skin and in the ears while we are working to control the underlying allergy. We are one of the few centers in the Houston area that specialize in intradermal allergy testing, the "gold standard" for allergy testing in dogs and cats. Without proper control of all of these allergy factors, your dog or cat may be miserable and they may keep everyone up at night!

Why is my pet so itchy?

It seems that this question gets more difficult to answer every year! There is a continuous flow of scientific information related to allergic disease in both humans and animals. Basically, allergies are caused by an abnormal reaction of the immune system to things that should be considered normal to the body. These would include many things, such as dust, dietary proteins, insects, pollens, danders, and molds. Pollens could be from trees, grasses, or weeds that are found in the pets surrounding environment. The allergens can typically gain passage into the body through inhaled routes or, more commonly, through contact with the skin. This is called transdermal absorption. This will start the cascade of an allergic response in sensitized individuals. The end result of this cascade is the production of chemicals in the body that make the patient itch. The itching will lead to trauma to the skin, therefore allowing more allergens to enter. It's a vicious cycle that can disrupt the normal way of life for all those involved.

What are the most common types of allergies?

While virtually anything can be an allergen, there are certain types of allergies that are encountered more frequently in dogs and cats:

Flea bite hypersensitivity (aka Flea allergy dermatitis or FAD): This is a very common form of allergies in both dogs and cats. All of our four-legged friends living in this area of the country should be involved in a good flea control program all year round. One of the major allergens involved in this type of allergic reaction is the flea's saliva. If a patient is hypersensitive to flea saliva and gets bitten by a flea, the allergic reaction may commence significantly. This can lead to intense itching and discomfort. Many patients with other forms of allergies may have those allergic responses exacerbated with flea bites. There are many topical and oral flea products available that are safe and effective. We should always keep in mind that we will rarely see any fleas, but they may be there!

Cutaneous adverse food reaction (AFR): There are many ingredients in the diet that may trigger allergies in dogs and cats. The main cause of these reactions tend to be dietary proteins. There is a common misconception that grains and gluten are the offending substances. While it is possible to have an allergy to these ingredients, the scientific data does not support this suggestion. Quality of the diet may play a factor when considering these two categories. Instead, it is important to focus on ingredients, such as chicken, beef, or fish as possible offending substances. It should be noted that clinical signs of AFR and environmental allergies may be identical! This means that it would be hard to tell the difference between the two without a proper history to support one or the other. Some dogs may show signs of gastrointestinal disturbance, such as excess gas, vomiting, or loose stool. It is also possible to have a combination of food, flea, and environmental allergies!

Environmental allergies (aka Atopy or Atopic dermatitis): These allergies account for a large number of cases in dogs and cats. As mentioned above, airborne allergens can be inhaled or absorbed through the skin. This will incite an allergic reaction in sensitized individuals. Some patients may have a seasonal change in their level of itch, while others may have an itch all year long. We have to remember that indoor allergens are very important with this disease. Some dogs can even have allergic reactions to human dander! Again, CAFR and environmental allergies may present clinically identical, so one would need to rule out one or the other to obtain a diagnosis.

Contact allergies: These are very uncommon in dogs and cats. That being said, we should always keep in mind that they are a possibility. It could be something as simple as a reaction to plastic or concrete. These reactions typically happen over the sparsely haired skin of the patient, usually the stomach and/or groin. Fabric softeners, perfumes, and carpet freshners are all possible causes for this type of reaction.

How can I treat my allergic pet?

One of the best ways to manage allergic disease in both humans and animals is to avoid the offending substances. This is often easier said then done! In the case of FAD, a very strict eradication and control program must be established to lessen the likelihood that the patient will come into contact with a flea. Canine adverse food reaction can be managed by not letting the patient consume ingredients in the diet which are known to start an allergic reaction. This is typically ruled out by using a novel protein diet trial. If a known contact allergy exists, keeping the patient away from that substance would be very beneficial. When it comes to environmental allergies, these tend to be the most difficult to control. It's very hard to avoid a pollen or dust when you have allergies to these items. We can't shield our loved ones from all of the pollen that we have in the South! Many people will turn to oral medication as a temporary solution to control the clinical signs of allergic disease. These are typically in the forms of antihistamines, steroids, or other immunosuppressive therapy options. A more long term treatment plan would involve the use of allergen-specific immunotherapy to help the body in controlling the allergic disease.

What is allergen-specific immunotherapy?

Allergen-specific immunotherapy (ASIT) is a medical treatment option in both humans and animals. It involves the repeated injection of the offending allergens subcutaneously in an effort to teach the immune system not to over react to these substances. First, the patient is allergy tested. There are two forms of allergy testing. The "gold standard" test is called intradermal allergy testing (IDAT). In this form of testing, the patient is sedated, not under anesthesia, and multiple allergens are injected under the skin. These allergens are based on the patient's surrounding environment. The test is read to determine which allergens should be included in ASIT. The second form of testing is called serum allergy testing (SAT). This form of testing requires a blood sample be sent to a laboratory and then the levels of allergen-specific immunoglobulin E will be calculated. While this is not the prefered test in most patients, it could be used if withdrawl times of certain medications prohibit the IDAT. Based on the results of the allergy test, a mixture of allergens is created. It should be noted that this is not a medication, but simply a mixture of concentrated allergens. These injections will be given by the owner in their own home. Most dogs and cats do fantastic with receiving injections at home! Over time, the body's immune system may begin to regulate itself and the clincial signs of allergic disease may become fewer and fewer. This form of therapy is very cost effective and is wonderful for long-term control of the allergies. Some patients may even come off of the injections or receive them with a reduced frequency with continued use. It is currently the only form of therapy that we have that actually teaches the patient's immune system and builds up a response, instead of suppressing it. This therapy can be used as monotherapy or as part of a polytherapy program. We will work with you and your pet in coming up with the most comprehensive treatment plan, including this form of therapy as the cornerstone. So many of our patients do well with this therapy!