by Rita Hoffman [GREAT article - go to website to read the whole thing! - bfg]
In the presentation speech as winner of the 1913 Nobel Prize in Medicine for his work with anaphylaxis, Charles Robert Richet said, "We are so constituted that we can never receive other proteins into the blood than those that have been modified by digestive juices. Every time alien protein penetrates by effraction, the organism suffers and becomes resistant. This resistance lies in increased sensitivity, a sort of revolt against the second parenteral injection which would be fatal. At the first injection, the organism was taken by surprise and did not resist. At the second injection, the organism mans its defenses and answers by the anaphylactic shock."
...This hypersensitive state called anaphylaxis is now epidemic in young children who live every day of their life under threat of death from everyday, normally harmless substances. The numbers are staggering. According to Health Canada's web site, "It is estimated that 600,000 Canadians (two percent of the population) may be affected by life-threatening allergies, and the numbers are increasing, especially among children." (3) In 2005 Ontario passed a law to protect anaphylactic students at school while The Toronto Star reported an estimated 40,000 children in Ontario with anaphylaxis. (4)
Moderate. Urticaria is a moderate vascular reaction of the skin marked by hives or wheals and rapid swelling and redness of the lips, around the eyes, and in the neck region. It is usually extremely itchy. Urticaria may progress to anaphylaxis, which is considered life-threatening. Urticaria is the most common reaction in dogs.
Severe. The most severe reaction is anaphylaxis, a sudden, severe allergic response that produces breathing difficulties, collapse and possible death. Symptoms usually include sudden onset of vomiting, diarrhea, staggering, rapid drop in blood pressure, swelling of the larynx leading to airway obstruction (and inability to breathe), seizures and cardiovascular collapse or death. This reaction is life-threatening for your dog.
Both anaphylaxis and urticaria are reactions that are triggered by antibodies that the immune system has made to some portion of the vaccine and usually requires at least one previous exposure to the vaccine. The antibodies cause inflammatory cells like basophils and mast cells to release substances that cause the allergic reaction. The impact on the dog may be life threatening but if treated successfully the prognosis for long-term health is good. Mild reactions usually resolve without treatment.
Anaphylaxis is an extreme emergency. Your veterinarian will begin immediate emergency life support including establishing an open airway, oxygen administration, intravenous fluids to increase blood pressure and drugs such as epinephrine, diphenhydramine and corticosteroids. Dogs that survive the first few minutes usually return to normal health. Anaphylaxis usually occurs soon after vaccination, often while the dog is still in the veterinary clinic.
...Reactions are more commonly associated with vaccines for leptospira, rabies and parvovirus.