Page 991 - Veterinary Immunology, 10th Edition

VetBooks.ir Specific Allergic Diseases

Anaphylaxis

In its most extreme form, antigen administered rapidly to an
allergic animal will cause generalized mast cell degranulation and
massive mediator release. If the rate of release of vasoactive

molecules from these mast cells exceeds its ability to adjust to the
changes in its vascular system, an animal will undergo anaphylaxis
and may die.
Anaphylaxis is a severe, life-threatening systemic
hypersensitivity reaction triggered by sudden exposure to an

antigen in a highly sensitized animal. Its clinical signs are
determined by organ system involvement, which differs among the
major domestic animals (Table 30.1). Many of the symptoms result

from smooth muscle contraction in the bronchi, gastrointestinal
tract, uterus, and bladder, mediated by large amounts of histamine
and other amines released by degranulating mast cells and
basophils. It is often lethal unless treated promptly.

TABLE 30.1

Anaphylaxis in the Domestic Species and Humans

Species Shock Organs Symptoms Pathology Major Mediators
Horse Respiratory tract Cough Emphysema Histamine
Intestine Dyspnea Intestinal hemorrhage Serotonin
Diarrhea
Ruminants Respiratory tract Cough Lung edema Serotonin
Dyspnea Emphysema Leukotrienes
Collapse Hemorrhage Kinins
Dopamine
Swine Respiratory tract Cyanosis Systemic hypotension Histamine
Intestine Pruritus
Dog Hepatic veins Collapse Hepatic engorgement Histamine
Dyspnea Visceral hemorrhage Leukotrienes
Diarrhea Prostaglandins
Vomiting
Cat Respiratory tract Dyspnea Lung edema Histamine
Intestine Vomiting Intestinal edema Leukotrienes
Diarrhea
Pruritus
Human Respiratory tract Dyspnea Lung edema Histamine
Urticaria Emphysema Leukotrienes
Chicken Respiratory tract Dyspnea Lung edema Histamine
Convulsions Serotonin
Leukotrienes
The major shock organs of horses are the lungs and the intestine.

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