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Dog Allergy Glossary of Terms

Drs. Foster & Smith Educational Staff
Allergy Signs & Symptoms 
Allergies: How Veterinarians Test 
Dog Allergy FAQs 

Learning your pet has allergies can take many animal lovers by surprise. When our veterinarian tells us our animal has a condition, however minor it may be, pet owners often get anxious and confused. Trying to process all the information in front of us, we just nod our heads and wonder, walking back to the car after the appointment, why we didn't ask more questions.

The following is a list of terms veterinarians use - the ABC's of Allergies - which may help you understand your animal's newly diagnosed allergy condition:


  • A Disease is when one of the body's systems, tissues or organs does not work as it is supposed to.

  • Chronic means the disease or condition has been ongoing; your pet has had a long history or duration of the condition.

  • Acute means the onset of the condition was sudden and that your pet has had the condition for a short time.


  • A Sign means any abnormality that indicates the presence of a disease. A sign is found by the veterinarian in his physical examination of your pet. For instance, a sign of atopy would be a reddening of your pet's skin.

  • A Symptom is any abnormal function of the body or behavior indicating a disease process. An example of a symptom would be your pet scratching.

  • A Syndrome is a combination of signs and symptoms that suggests a particular disease in the mind of a veterinarian.


  • An Allergen is defined as any substance capable of causing an allergic reaction.

  • An Allergy occurs when any substance alters the response of your pet's body and immune system.

  • An Allergic Reaction is a response of the pet's immune system, following the inhalation, ingestion, or injection of an allergen.

  • Atopy is a specific type of allergic response to something your pet inhales, like pollen. It's also known as "allergic inhalant dermatitis."

Allergy Testing

  • RAST is an acronym for radioallergosorbent test, a blood test that measures reactions to possible allergens.

  • ELISA is an acronym for enzyme-linked immunosorbent assay test used to identify allergic reactions in the blood.

  • Intradermal skin testing is when specific allergens are injected just under the pet's skin in a specific pattern to see which allergen your pet reacts to.

What is Hypersensitivity?

Hypersensitivity is a synonym for allergy that encompasses four types:

  • Type I is an immediate reaction. For example, reactions to bee stings or penicillin. In animals, atopy, flea allergy dermatitis, and hives are also Type I sensitivities.

  • Type II is when the body has a hypersensitivity to its own cells. It is also called autoimmunity. An example is autoimmune hemolytic anemia, when the body produces antibodies which destroy its own blood cells.

  • Type III is in fact a severe version of Type II hypersensitivity. Antibodies attack cells in multiple body systems. An example is Lupus or Rheumatoid arthritis.

  • Type IV is a delayed hypersensitivity. This reaction occurs more than 24 hours after the body is exposed to the allergen. Allergic contact dermatitis, or when your pet is allergic to chemicals, dyes, or metals, is an example of a Type IV hypersensitivity.
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