Also known as "allergic shock", anaphylaxis is a severe, rapid onset and life-threatening reaction to an allergen. Common allergens can include:
- Insect bite or sting.
- Drugs, particularly antibiotics.
- Food allergies.
It occurs when the body mounts an over the top reaction to a perceived threat (the allergen). The body will have had exposure to the allergen before, which would have stimulated an immune response, future exposures can result in more severe responses.
During anaphylaxis, IgE (antibodies) bind to the antigen (the allergy-producing substance), which triggers receptors on mast cells and basophils to release their cytotoxic granules. These contain compounds including histamine and serotonin, which result in constriction of the airways, making breathing difficult, and causing the blood pressure to drop.
What are the symptoms of anaphylaxis?
Onset is rapid, usually within minutes (but sometimes hours) of exposure. Common symptoms include:
- Difficulty breathing.
- Rapid swelling of the affected area.
- Facial swelling.
- Pale gums.
- Gastrointestinal symptoms such as vomiting or diarrhea.
- Low body temperature.
How is it diagnosed?
Obviously presenting symptoms can be indicative of anaphylaxis. Immediate treatment is necessary to save your cat's life. However, once the emergency has been addressed, your veterinarian may wish to run some tests to determine the cause of the allergic reaction (if it is not known). This usually involves a patch test. A minute amount of several common allergens are pricked onto your cat's skin, the area is then covered and re-examined for signs of redness and swelling 24-48 hours later.
If your cat's heart has stopped beating, you will need to perform CPR on him. To check for a heartbeat, press against the rib cage over the heart.
If possible, have somebody administer the CPR as you transport your cat to the veterinarian. Call on the way so that they can be on standby.
If he is wearing a collar, loosen or remove it. Give him plenty of reassurance as he is transported to the vet. If possible, wrap him in a blanket and lie him on his side, with his legs slightly elevated.
How is it treated?
Anaphylaxis is a medical emergency and must be treated immediately. Administration of epinephrine (adrenaline) will be necessary. This is an intramuscular injection which counteracts the adverse effects such as relaxing the airways, making breathing easier, increases blood pressure by causing constriction (tightening) of the blood vessels (which dilate during anaphylaxis) as well as preventing the further release of cytotoxic granules.
Supportive care such as oxygen therapy and IV fluids may also be given to assist with breathing.
How is it managed:
Avoidance of the allergen if possible, this is why it is important to undergo skin patch tests to try and determine the cause. Switching medications or food if these are the cause.
If your cat has had an allergic reaction to a drug or vaccination, be sure to alert your veterinarian, even if it occurred at his surgery, it is always a good idea to remind him prior to administration of medications.