Acute manifestation of a Type I hypersensitivity reaction mediated through the rapid introduction of an antigen into a host having antigen-specific antibodies of the IgE subclass. The binding of antigen to mast cells sensitized with IgE results in the release of preformed and newly synthesized chemical mediators is called anaphylaxis reaction. It may be localized (atopy) or systemic (anaphylactic shock). Anaphylactic reactions are further 4-5 types depending upon the type of chemical mediators released and causes of their release and activation.
How Anaphylaxis Sets Up:
- First exposure of the patient to a particular antigen (allergen) causes a humoral response and results in production of IgE, which binds to the surface of mast cells.
- Second exposure to the antigen results in cross-linking of two or more IgE molecules on the cell surface which results into mast cell degranulation and activation then the release of mast cell granules initiates an anaphylactic reaction. Major mast cell-derived mediators include histamine, eosinophilic chemotactic factor, arachidonic acid, metabolites (e.g., prostaglandins, leukotrienes, and thromboxanes), platelet-activating factor, and proteases. These mediators cause an inflammatory response by increasing vascular permeability, smooth muscle contraction, inflammatory cell influx, and tissue damage as explained by pet clinic in Gurgaon.
Depend on the route of antigen exposure, the dose of antigen, and the level of the IgE response. More is the dose of antigen exposure, more severe will be the clinical signs and symptoms.
Localized anaphylaxis may result into atopy which is more common in dogs as compare to dogs. Anaphylaxis reactions are more common in 3-5 years old animals due to their more roaming behaviour and unusual eating habits.
1. Gastrointestinal: Anaphylaxis reaction causes salivation, vomiting, and diarrhea as noticed by Dr. Sapna Soni (C.E.O. at Pet Prime Veterinary Clinic).
2. Hepatobiliary : Anaphylaxis reaction may occur in liver because of portal hypertension and vasoconstriction. It mainly occur in dogs.
3. Respiratory: Respiratory anaphylaxis if occurs, may cause dyspnea and cyanosis. It is more common in cats as compare to dogs.
4. Skin/Exocrine: As skin is the largest organ of the body, so skin is the most affected part of the body due to anaphylaxis reaction. It may cause pruritus, urticaria and edema as noticed by Pet Prime Veterinary Clinic, the best pet clinic in Gurugram.
Anaphylactic reactions can be diagnosed by:
- Intradermal skin testing to identify allergens.
- Radioallergosorbent test can be done to quantify the concentration of serum IgE specific for a particular antigen.
How to treat anaphylaxis:
Epinephrine hydrochloride parenterally for shock can be used. Corticosteroids for shock prednisolone sodium succinate (2 mg/kg IV q8h) or dexamethasone sodium phosphate (0.25 mg/kg IV q12h) can be used. Atropine sulfate (0.04 mg/kg IM) to counteract bradycardia and hypotension. Aminophylline (10 mg/kg IM or slowly IV) in severely dyspneic patients. If condition limits only to the localized area, then only local treatment can be given.
Avoid exposure to any antigen if it is food born.