Basics Anaphylaxis is a severe and potentially life-threatening allergic reaction that
can occur in both dogs and cats. It is a rapid and intense immune response
to an allergen, which is a substance that triggers an allergic reaction.
Anaphylaxis can lead to serious respiratory, cardiovascular, and
gastrointestinal complications.
Urticaria: cutaneous manifestation of anaphylaxis, consisting of pruritic
wheals
Angioedema: nonpainful cutaneous and visceral edema (regional or
generalized) that is one of the hallmarks of anaphylaxis
Anaphylaxis does not always involve a previous and sensitization.
It should be suspected in patients with unexplained acute cardiovascular and
respiratory collapse. Fluid therapy and epinephrine are the first lines of
treatment for severe anaphylaxis.
Types Type I Anaphylaxis: This is the most common type and occurs within minutes
of exposure to an allergen. It involves the release of histamines and other
chemicals, causing rapid and severe symptoms.
Type II Anaphylaxis: This is a more delayed reaction that can occur hours
after exposure to an allergen. It is less common and involves a different
immune response.
Causes Anaphylaxis can be triggered by various allergens, including insect bites or
stings, certain foods, medications, vaccines, and environmental substances
like pollen or dust.
Signalment Pets of any age, breed, or sex can develop anaphylaxis. However, some pets
may be more predisposed due to a history of allergies or sensitivities.
Concurrent Conditions Underlying allergies, asthma, or other immune-related conditions may
increase the risk of anaphylaxis.
Pathophysiology Anaphylaxis occurs when the immune system overreacts to an allergen,
releasing an excessive amount of histamines and other inflammatory
substances. This leads to widespread blood vessel dilation, decreased blood
pressure, and compromised organ function.
Clinical Signs - Early Stages vs Later Stages
Early Stages: Itching, hives, facial swelling, vomiting, diarrhea, restlessness,
difficulty breathing, coughing, sneezing.
Later Stages: Weakness, collapse, pale gums, rapid heart rate, low blood
pressure, loss of consciousness.
Diagnosis Testing Diagnosis is based on clinical signs, history of exposure to allergens, and
ruling out other potential causes. It can be challenging as symptoms can
mimic other conditions.
Blood pressure: monitor for hypotension
CBC, serum chemistry, urinalysis: generally unremarkable, may have
decreased platelet count
Thoracic radiographs: to rule out pulmonary disease if respiratory distress or
tachypnea is present
Heartworm testing: antigen (dogs) or antigen and antibody (cats)
Coagulation testing may reveal hypocoagulability
General blood work including Slide Agglutination Test to check if there is
increased immune system activity damaging RBCs which could be fatal if not
recognized in time.
Challenges in Diagnosis Identifying the exact cause can be challenging due to the diverse potential
underlying allergens.
Treatment The main goal of treatment is to stabilize the pet and reverse the allergic
reaction, as well as to manage complications and prevent recurrence. Fluid
support may be needed.
Medications & Handling Epinephrine: Counteracts severe symptoms, but should only be administered
by a veterinarian.
Antihistamines (Diphenhydramine, Famotidine) and Corticosteroids: Help
control inflammation and allergic reactions.
Fluid Therapy: Supports blood pressure and organ function.
Bronchodilators: Open airways in cases of respiratory distress.
Special Medicine Handling
Administer medications as directed by your veterinarian. Epinephrine should
be handled with care due to its potency.
Common Complications Common: Skin infections from scratching, prolonged respiratory distress.
Rare: Blood clotting issues, kidney or liver damage.
Rare & Severe Complications
Worst: Severe respiratory or cardiovascular collapse, leading to death.
Effect on Lifespan and quality of life
Untreated anaphylaxis can be fatal. Prompt treatment can improve the
chances of recovery, but long-term consequences can affect the pet's quality
of life.
Prognosis - Early Stages vs. Later Stages
Early treatment greatly improves the prognosis. Late-stage anaphylaxis has a
poorer prognosis due to the increased risk of severe complications.
Signs of Recovery Improved breathing, stable heart rate, regained consciousness, decreased swelling.
Recovery Testing Blood tests, imaging, and monitoring vital signs can help confirm recovery.
Likelihood of Recurrence
Pets that have experienced anaphylaxis are at higher risk for future episodes.
Signs to Watch Out For Persistent coughing, difficulty breathing, swelling, restlessness, lethargy.
In case of deterioration of pets condition or delay in recovery
Contact your veterinarian immediately. Additional treatments, monitoring, or
hospitalization may be necessary.
Recommended Monitoring
For mild cases (skin reaction only), monitoring at home for recurrence
For severe cases: Frequent monitoring should be continued for 24-48 hours
after reaction.
• Heart rate, respiratory rate, respiratory effort, pulse rate, pulse quality,
mentation, mucous membrane colour, capillary refill time, temperature,
urine output
• Blood pressure
• Electrocardiogram
• Pulse oximetry or arterial blood gases
• Packed cell volume and total solids
• Serum biochemistry analysis
• Coagulation testing
Prevention Identify and avoid triggers, discuss allergen-specific immunotherapy with
your vet.
Feeding Instructions Allergies to certain foods can trigger anaphylaxis. Consult your vet for
suitable diets if food allergies are suspected.
Zoonoses Anaphylaxis is not contagious, but some allergens can affect humans.
Discuss potential risks with your veterinarian.
This is a generalized information handout. Always consult your veterinarian for personalized advice and care for your pet. SKVH Client Handouts © 2023
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