The benefits and limitations of allergy testing
Allergy testing can be very effective in identifying the underlying cause of atopic dermatitis, a condition that is typically caused by the inhalation of pollen, mold spores, dust, and other allergens. Allergy testing is not, however, recommended for the diagnosis of food allergies. (Diagnosis of food allergies requires a food trial with a hypoallergenic diet.)
It is also important to note that allergy testing cannot be used to determine whether or not a patient has atopic dermatitis. Atopic dermatitis must first be diagnosed based on history, clinical signs, and the exclusion of other skin diseases. Allergy testing is only beneficial in seeking the underlying cause of already-diagnosed atopy, in preparation for immunotherapy and other treatments designed to decrease reactions to specific allergens.
Allergy testing in dogs typically takes one of two forms: intradermal skin testing, or blood (serum) testing. Each method has its own unique advantages and disadvantages, from both a medical standpoint and a client standpoint.
What are the signs of atopy?
The most common signs of allergic skin disease in dogs are redness and itching. In some cases, dogs may scratch themselves until their skin is raw, leading to more obvious skin lesions and secondary skin infections. These signs can be seen with any type of allergic skin disease: food allergy, flea allergy, or atopy. See the handout “Inhalant Allergies (Atopy) in Dogs” for more information on this allergy.
Immunotherapy for Allergies in Dogs and Cats
Allergen-specific immunotherapy (ASIT), commonly referred to as allergy shots, are the most effective way to address airborne allergies, sometimes even resulting in a permanent cure. This sounds wonderful but there is an expense involved plus it commonly takes a year to realize results and will not help the pet (or person) who is experiencing symptoms right now. ASIT involves the use of an individually-made serum, created using small amounts of allergens (proteins against which the person or pet reacts). The patient periodically receives injections of gradually increasing amounts of allergens until a maintenance level is reached. This method of allergy control uses the patient’s own immune system rather than drugs to address the symptoms of allergy. It may seem odd that injecting someone with the very substances to which they are allergic helpful but, in fact, it works. All other therapies for airborne allergies basically aim to suppress the symptoms; allergen-specific immunotherapy is the only therapy that actually works against the immunological disease. The earlier in the allergic patient’s life ASIT is started, the better the results. Regular rechecks are needed through the course of ASIT.
How to diagnose allergy in dogs and cats – blood allergy test.
While not usually life threatening, allergies in dogs do cause discomfort. Most symptoms are associated with dermatologic problems but some can also lead to chronic respiratory issues in some dogs if untreated for long periods of time. Sometimes an owner will bring their dog to a veterinary appointment, suspecting a serious medical condition and end up finding out that their canine companion has an allergy.
Most allergies develop in the second year of life for dogs. In the first year, the dog will be exposed to many types of allergens primarily through contact with the skin. A smaller number of allergies may be caused by food (usually the protein source) and inhalant (things they breathe in that are in the air). In the second year of life, the dogs immune system will overreact to the antigen(s) causing release of immune cells which release inflammatory substances ( such as histamine) which lead to symptoms of itching. Rarely is a dog allergic to just one thing. Most allergic dogs are born with a less than optimal skin barrier which allows for antigens to enter the skin more easily. Dogs that suffer from allergies have abnormal skin and a less than optimal immune response which allows for secondary infections to occur. Typically, dogs do not suffer from a single allergy, but instead, dogs with sensitivities to allergens have a host of issues. You must understand that dog allergies are due to a complex set of issues that tends to change as the dogs environment changes.
Because these symptoms can have several possible causes, we recommend making a veterinary appointment immediately if you notice your dog exhibiting any of the above symptoms. Early diagnosis and treatment of dog allergies not only increases the likelihood of your dogs treatment being successful, but can also be less expensive than delaying treatment. The longer you wait, the more your dog suffers and more severe the secondary infections can become.
The first step to determining the cause of your dogs symptoms is a thorough exam by your veterinarian. In addition to looking for external skin parasites such as fleas and mites, your veterinarian will want to do some diagnostics to help him/her determine what types of infections may be present. After diagnosing and treating for external parasites and infections, your veterinarian may want to discuss allergy testing. Once your veterinarian believes that allergies are the root cause of skin irritation/infections and discomfort, then they may recommend testing for specific allergens. There are many things to test for in determining what your dog may be causing the allergies for your dog. Dog allergens fall into the following groups:
Contact allergies such as flea, food and dust/pollen allergies are by far the most common cause of allergies in dogs. These allergens can cause an allergic reaction in the body that focuses largely on and within the epidermis, causing severe irritation. The result is a dog scratching itself to the point that skin infections and injuries can occur.
