Overview
Anaphylactic shock, or anaphylaxis, refers to a rapidly developing and serious allergic reaction that affects a number of different areas of the body at one time (in most cases allergic reactions are mild, and rarely result in anaphylaxis). Anaphylactic shock can occur in most mammals including dogs and people, but the effects and symptoms of anaphylactic shock in dogs differ from the effects and symptoms of anaphylactic shock that other mammals experience. Once anaphylaxis develops, emergency medical treatment is immediately required. Once at the ER, your veterinarian's treatment objectives are as follows:
- Steroids to bring down inflammation
- Benadryl to stabilize mast cells
- IV fluids to correct cardiovascular effects - hypotension and relative hypovolemia
Causes and Effects
Dogs can experience an anaphylactic shock condition if they have a severe reaction to a specific allergen. This allergen can be from an insect bite, a snake bite, a type of medication, environmental allergen (molds, pollens, etc), or a certain food ingredient. Whatever the cause, exposure to the allergen produces a heightened response in the body, and the response can take a matter of minutes to progress into a life threatening situation.
When an anaphylactic reaction occurs in a dog’s body, exposure to the allergen causes certain cells in the body, called mast cells, to release extremely large amounts of histamine and other immune regulating compounds. These chemicals are normally used in the body to combat regular allergies and to heal wounds, but in large quantities they lead to anaphylactic shock.
Once the large amounts of histamine and immune regulators are released, a chain reaction begins. In response to the mast cells release of compounds the blood vessels in the body swell, and as a result blood pressure suddenly drops. Continual swelling of the vessels causes damage to the organs, vessels, and tissues in the body.
In most mammals anaphylactic shock affects the lungs first, and then the vessels within the lungs and bronchial airways are affected. In dogs, the liver and gastrointestinal systems are affected first. Part of the reason why dogs bodies react differently is due to the gastrin secreted by mast cells that are degranulating (the gastrin results in gastric acid secretion and then vomiting and diarrhea result). Once a dog experiences anaphylactic shock, exposure to that allergen will continue to result in an anaphylactic reaction.
Prevention
The best way to prevent anaphylactic shock is to avoid any substances to which your dog may be allergic. Since dogs are generally curious animals and find their way into trouble easily, it can sometimes be difficult to prevent or know if your dog has come into contact with an allergen until it’s too late. If your dog begins displaying the symptoms of an allergic reaction , it’s possible that giving him or her Benadryl at 1 mg/lb at first sign can help stabilize the mast cells that cause anaphylactic shock. If there is a severe allergic reaction, an epi-pen (Epinephrine) may also be used to help prevent anaphylactic shock.