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                                                                 Allergy Testing & Immunotherapy in Dogs

 

Allergy testing is a way to get a positive diagnosis for atopy (inhalant dermatitis) and to a lesser extent for contact allergies. Scratching, licking the feet, chewing, and red irritated skin are all symptoms of atopy in the dog. Atopy is the name given to allergies that result from breathing in pollen, dust, or mold. Other than flea bite allergies, atopy is by far, the most common cause of allergies in dogs. When an allergy to a specific substance can be identified, the dog can receive immunotherapy (hyposensitization injections).

Types of allergy testing:


There are two basic types of allergy testing. The most common is a blood test that checks for antigen-induced antibodies in the dog's blood. 
The other type of testing is intra-dermal skin testing. In this test, a small amount of antigen is injected into the skin of the animal and after a short  period of time, the area around the injection site is observed to determine if the animal is allergic to the agent. Intradermal Testing is done by Veterinary dermatologist.

  • Blood testing

To perform either of these two tests to determine what substances an animal may be allergic to, a blood sample is drawn from a suspected atopic dog and sent into the lab, we use Spectrum Lab. The blood is screened for a reaction to a broad range of allergens including pollens, dust, and molds that are common to the geographical area in which the dog or cat  lived. Tests for reactions against different foods and contact allergies such as cotton or nylon can also be done, although, the tests perform less accurately for these allergens. The testing generally takes several weeks. Of all of the blood tests performed, the ELISA is the most accurate.

The blood test can also be  used in special circumstances in which intra-dermal skin testing cannot be performed, such as:

  • The skin is too unhealthy to test either due to infection or severe inflammation.
  • Prolonged drug withdrawal for antihistamines and corticosteroids cannot be tolerated.
  • The dog is very young.
  • The dog is a show dog whose hair cannot be clipped.
  • Intra-dermal skin testing is unavailable.
  • The intra-dermal skin test (IDST) is negative, yet atopy is still suspected.

 

  • Intra-dermal skin testing

Intra-dermal skin testing is the gold standard of allergy testing for atopy. The animal is sedated, and an area on his side is shaved down to the skin. On this shaved area a small amount of antigen is injected into the dog's skin. This is done in a specific pattern and order so that if the dog shows a small raised reaction, the offending antigen can be identified. After a period of time (hours), the shaved area is examined to detect which antigens, if any, created a reaction. Reading the reactions and determining if they are large enough to create an allergic reaction in the dog is somewhat of an art. This is where having a veterinary dermatologist really pays off.. That is why for Intra-dermal testing we refer to Veterinary Dermatologist.

Successful identification and treatment of atopic dogs by this method is listed to be as high as 75%. This test works best if performed during the season when the allergies are at their worst. Animals to be tested must not have been treated with steroids or antihistamines for several weeks to months before testing. The exact time differs with the drug used and type of test performed.

The basics of all allergy tests:

The blood and intradermal skin tests have some similarities:

  • These tests work best if performed during the season when the allergies are at their worst.
  • Once the allergens for the dog are identified, an appropriate immunotherapy is manufactured for that specific dog, and treatment can begin. After the offending antigens are identified, then a mixture of these antigens can be formulated into a hyposensitizing injection. Depending on the type of agents used, these injections will be given over a period of weeks to months until the dog or cat develops immunity to the agents. After initial protection, an occasional booster may have to be given.
  • Before any animal is tested for allergies, a complete diagnostic workup ruling out other potential causes of skin problems should be performed. External parasites such as fleas or mites, fungal or yeast infections on the skin such as Malassezia, and chronic bacterial infections must be eliminated. In addition, the possibility of concurrent hypothyroidism must be ruled out.
  • It is often recommended that animals be placed on a homemade or hypoallergenic diet for 12 weeks before undergoing testing to ensure that a food allergy is not the cause. After the cause of the skin problem has been identified as atopy, then it is time to do the test.

We will take this time to warn pet owners that if they are not committed to the necessary follow-up treatment, which involves numerous injections over a long period of time, then all of these tests may be a waste of time and money.

Who should be allergy tested?

Allergy testing should be considered for any animal that is suffering from allergies that occur for more than four months out of the year, and or do not respond to traditional treatment. Due to the increased time and cost necessary to do skin testing, most mild cases of allergies are treated with a combination of avoidance, fatty acids, and antihistamines. Unfortunately, there are many animals that suffer from moderate or severe allergies that should be tested and treated, but are not.

Allergy testing is rarely done to diagnose food allergies.

 

 

Summary

 

Allergy testing is the best diagnostic tool and the best road to treatment for dogs that are suffering from moderate and severe allergies. There are several different testing methods available and the intradermal skin testing is the one that is most recommended and performed by veterinary dermatologists, however, the blood testing available now is much more accurate than it was in the past. The hyposensitization injections have had good results in reducing the symptoms of allergies in many dogs.

 

TREATMENT OPTIONS for Itcy dogs and cats

Symptomatic Therapy

Treating the dogs symptoms may include; cool baths with or without colloidal oatmeal, , or medicated shampoos. This can be done frequently but provides only temporary relief. Caution should be used with sprays and ointments because many contain potentially harmful substances. Cortispray is a low dose, non-systemic cortisone spray which can be safely used for short periods of time.

Immunotherapy

Allergy shots are very safe and many people have great success with them, however, they are very slow to work. It may be six to twelve months before improvement is seen. about intradermal skin testing for inhalant allergies. The average success rate of immunotherapy is 70-75%.

Corticosteroids

These compounds reduce itching by reducing inflammation. Unfortunately, they also affect every organ in the body. According to Dr. Ackerman, steroids should be considered only when the allergy season is short, the amount of drug required is small or as a last resort to relieve a dog in extreme discomfort. Side effects can include increased thirst and appetite, increased need to urinate and behavioral changes. Long term use can result in diabetes, decreased resistance to infection and increased susceptibility to seizures. In short, alternatives to steroid therapy should always be considered.

Antihistamines

Antihistamines can be used with relative safety in dogs. About one third of pet owners report success with them. The major drawback, as with people, is sedation. Dr. Ackerman recommends that a minimum of three different types of antihistamines be tried before owners give up on this therapy.

 

Omega-3 and Omega-6 Fatty Acids

These fatty acids are natural anti-inflammatory agents. They reportedly are helpful in 20% of allergic dogs. They are certainly worth a try because they are not harmful and have virtually no side effects. Omega-3 fatty acids are found in fish oils (especially krill and cod) and omega-6 fatty acids are derived from plants containing gamma-linolenic acid (GLA), such as oil from the evening primrose. These supplements are different from those sold to produce a glossy coat. They tend to reduce inflammation that may lead to skin sores but are not as effective in reducing itching.

Environmental Control

If you know which substances your dog is allergic to avoidance is the best method of control. Even if you are desensitizing the dog with allergy shots, it is best to avoid the allergen altogether. Molds can be reduced by using a dehumidifier or placing activated charcoal on top of the exposed dirt in your house plants. Dusts and pollens are best controlled by using an air cleaner with a HEPA filter. Air conditioning can also reduce circulating amounts of airborne allergens because windows are then kept closed.

Prevention

While there is nothing you can do to prevent a rescue dog from developing allergies, breeders should be aware that allergic dogs SHOULD NOT BE BRED!!! Dr. Johnson confirmed that there is clinical proof that allergies are inherited!

  

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