Autoimmune Disorders
Autoimmune disease is defined as the production of antibodies the body’s own tissues. Most often the loss of self-tolerance leads to the inflammation and breakdown of specific body tissues which causes dysfunction in those tissues. It is thought that viral or bacterial infection may trigger the onset of autoimmune disease though the process continues after the infection has been neutralized. Other theorized causes include ageing and iatrogenic causes such as medications that lead to suppression or alteration of the immune system. Hypersensitivity reactions occur when the body has an improper response to an antigen causing an immunity response. This antigen maybe self or non-self. There are 4 main types of hypersensitivity reactions in the body. Of the 4 types, 3 of them can also be autoimmune diseases.
Type I Reactions
In a Type I hypersensitivity reaction, the animal has been previously exposed to a specific antigen and produces an of antibodies when re-exposure occurs. It is an exaggerated and immediate response. IgEs attach to mast cells and basophils which increase histamine release during a type I reaction resulting in constriction of airways, vasodilation and itchiness. These reactions are more commonly known as .
Anaphylactic Shock
Anaphylactic shock is a rare, life-threatening, immediate allergic reaction to food, medication, or an insect sting. The most common signs occur within seconds to minutes after exposure to the antigen. These signs include severe respiratory distress and the sudden onset of diarrhea, excessive drooling, shock, seizures, coma, and death. The horse's gums are very pale, and the limbs feel cold. The heart rate is generally very fast, but the pulse is weak. Facial swelling does not usually occur, but there may be itchiness around the face and head. Treatment is epinephrine
Hives and Swelling
Urticaria and areas of swelling are caused by allergic reactions to drugs, chemicals, something eaten, insect bites, or even sunlight. They generally develop within 20 minutes of being exposed to the antigen. Hives are the least severe type of anaphylactic reaction. Small bumps occur on the skin. Often, the hair stands up over these swellings and sometimes they itch. Swelling is most often noticed on the face, especially on the lips, the muzzle, and around the eyes, but may also occur on the body or legs. Hives and swelling are usually not life threatening and typically go away by themselves once the cause of the allergic reaction is removed or passes through the body. Veterinarians often treat these reactions by providing corticosteroids or antihistamines.
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