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54 Anaphylaxis

Technician Tips Client Education SUGGESTED READINGS
• Curved-tip syringes facilitate infusion of • Although uncomfortable, inflammatory anal Muse R: Diseases of the anal sac. In Bonagura JD,
VetBooks.ir tions. Some patients need sedation for effec- • Persistent clinical signs may indicate an AUTHOR & EDITOR: Rance K. Sellon, DVM, PhD,
anal sacs with antibiotic-containing prepara-
sac disease is not usually a major health
et al, editors: Current veterinary therapy XIV, St.
threat.
Louis, 2009, Saunders Elsevier.
tive expression and treatment of anal sac
disease.
unrelated disorder.
• Avoid overly aggressive manipulation of the • Anal sac masses, even small ones, should not DACVIM
anal sacs while emptying the contents. be ignored.

Anaphylaxis

BASIC INFORMATION an antibody molecule (immunoglobulin E • Cytokine synthesis also occurs, contributing
[IgE]) that has been formed from a previous to the inflammatory response.
Definition exposure. Alternatively, in animals without previous
An acute hypersensitivity reaction results in • Reactions occurring without previous exposure exposure to the antigen:
the generalized release of inflammatory media- were historically referred to as anaphylactoid • Exposure to the antigen or hapten results in
tors from basophils and mast cells. This life- reactions but more recently have been grouped activation of the complement cascade, leading
threatening systemic allergic reaction can result with anaphylactic reactions because their to production of anaphylatoxins (C3a and
in cardiovascular collapse, respiratory distress, clinical presentation is identical. C5a), which cause activation of mast cells and
and death. basophils and release of primary mediators
• Urticaria: cutaneous manifestation of ana- HISTORY, CHIEF COMPLAINT not involving an antibody response.
phylaxis, consisting of pruritic wheals • Recent exposure to an inciting antigen or • Mast cells can also be stimulated directly.
• Angioedema: nonpainful cutaneous and hapten (e.g., vaccine, medication, food Activation, synthesis, and release of
visceral edema (regional or generalized) that ingredient, heartworm) inflammatory mediators result in peripheral
is one of the hallmarks of anaphylaxis • Agitation vasodilation, increased vascular permeability,
• Vomiting/diarrhea hypotension, bronchospasm, laryngeal edema,
Synonyms • Hypersalivation increased airway secretion production, intestinal
Allergic reaction, anaphylactic reaction/shock, • Respiratory distress hypermotility, cardiac arrhythmias, stimulation
type I hypersensitivity, urticaria (hives) • Collapse of pain receptors, and pruritus.
• For urticaria, severe pruritus
Epidemiology • For angioedema, swelling
SPECIES, AGE, SEX DIAGNOSIS
Most species; no age or sex predisposition PHYSICAL EXAM FINDINGS
• Wheals, facial angioedema Diagnostic Overview
GENETICS, BREED PREDISPOSITION • Weakness or acute collapse The diagnosis is based on history and physical
Boxers and pit bulls are most often affected • Mentation changes: depression or excitation exam findings alone. It is essential that treat-
with urticaria. • Evidence of hypoperfusion (pale mucous ment for anaphylaxis be instituted before
membranes, prolonged capillary refill time, extensive diagnostic testing because the prompt
RISK FACTORS poor to nonexistent pulse quality) initiation of treatment is a primary determinant
• Previous exposure to an antigen or hapten • Tachycardia of survival.
(molecules that attach to cells, conferring • Dyspnea (cats)
antigenicity) suspected to cause anaphylaxis • Coma Differential Diagnosis
increases risk, but previous exposure is not • Death • Dermatologic disease
always recognized. • Cardiorespiratory disease (severe cases)
• Can be triggered by a number of medications Etiology and Pathophysiology ○ Shock (hypovolemic, cardiogenic, septic)
(e.g., hormones, antibiotics, chemotherapeu- Anaphylactic reactions: ○ Pulmonary edema
tic agents, parasiticides, human albumin, • Initial exposure to an antigen results in the ○ Cardiac arrhythmias
vaccines), antigens (e.g., heartworms, bee production of specific IgE antibody. ○ Feline asthma
sting), or mast cell tumor degranulation • Subsequent re-exposure to the antigen results • Acute gastrointestinal disease
in the binding of the antigen to IgE on the
GEOGRAPHY AND SEASONALITY surface of basophils in circulation and mast Initial Database
• Summer or warm weather for insect-related cells in tissues. • Blood pressure: monitor for hypotension
anaphylaxis • Activated basophils and mast cells release • CBC, serum chemistry, urinalysis: generally
• Geographic areas where mosquitos that carry granules containing primary mediators of unremarkable, may have decreased platelet
heartworm are present anaphylaxis: histamine, heparin, proteases, count
and chemotactic factors. • Thoracic radiographs: to rule out pulmonary
Clinical Presentation • Activation of the arachidonic acid cascade disease if respiratory distress or tachypnea
DISEASE FORMS/SUBTYPES results in release of secondary mediators, is present
• Anaphylactic reactions occur because of the including leukotrienes, prostaglandins, • Heartworm testing: antigen (dogs) or antigen
interaction of an antigen or hapten with thromboxanes, and platelet-activating factor. and antibody (cats)

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