Autoimmune Disease in Dogs
Autoimmune disease refers to conditions in which the immune system does not work properly. Specifically, it mistakenly
sees some part of the body as foreign and starts to attack it. This page looks at the causes and different types of canine autoimmune disease.
The immune system is the dog's first line of defense system against foreign substances. It is made up of a complicated network of white blood cells, antibodies, and
other substances that patrol, reject, and eliminate foreign proteins (i.e. proteins that do not belong to the body, such as bacteria, viruses, pollen, etc.). This network of
defense system is designed to distinguish "self" cells from "non-self" cells by "markers" found on the surface of every cell in the body. Simply put, by comparing the
specific molecular features of foreign proteins ("non-self" cells) to the body's own proteins ("self" cells), the immune system can tell which ones are foreign and then work
to reject or eliminate them from the body.
However, when the immune system fails, problems occur. The immune system can fail in several ways:
This page looks at autoimmunity - An improper immune response that occurs when the immune system reacts to the wrong proteins and attacks the body itself, resulting in
different types of autoimmune disease.
- The immune system sometimes reacts to the wrong thing (autoimmunity).
- It over-reacts (hypersensitivity).
- It does not react at all (immunosuppression and immunodeficiency).
Different Types of Autoimmune Disease in Dogs
Autoimmune diseases can affect a single organ, or it can be systemic, i.e. sometimes the antibodies target not only one organ but multiple areas of the dog's body, causing
problems to arise in more than one organ or body part.
Examples of canine autoimmune diseases include:
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- Primary Addison's disease: In this disease, the adrenal glands are
affected and they fail to produce sufficient corticosteroid hormones.
- Hypothyroidism: Most cases of hypothyroidism in dogs are caused
by autoimmune thyroiditis which is an autoimmune disease that results in the atrophy and destruction of the thyroid gland tissue, causing insufficient production
of the hormone thyroxine. Dogs with this disease have metabolic rates that are below normal as a result.
- Pemphigus (Autoimmune Skin Diseases): In pemphigus, the walls of the
skin cells are targeted by the antibodies. As a results, these cells lose their ability to remain attached and separate, forming pustules, blebs (irregular bulges in the
plasma membrane of a cell), and vesicles (small fluid-filled blisters). There are four types of pemphigus in dogs - pemphigus foliaceus, pemphigus erythematosus, pemphigus
vulgaris, and pemphigus vegetans. Pemphigus folliaceus is the most common autoimmune skin disease in dogs.
- Autoimmune Hemolytic Anemia: This is a blood disease in
which the immune system launches an autoimmune response against the body's red blood cells. Specifically, the red blood cells are destroyed prematurely by auto-antibodies
that attack the antigens on the surface of the cells.
- Immune-Mediated Arthritis: Immune-mediate arthritis is a group of diseases in which antibodies attack the
dog's own connective tissue, resulting in either erosive arthritis (rheumatoid arthritis)
and nonerosive arthritis. In rheumatoid arthritis, the cartilage and joint surfaces are destroyed. In nonerosive arthritis, there is inflammation with no tissue damage.
- Systemic Lupus Erythematosis (SLE): This is a systemic autoimmune disease in
which antibodies target and systemically affect different body organs (the skin, heart, kidneys, joints, nervous system). As such, a variety of symptoms can arise depending
on which organ(s) the antibodies attack.
Causes of Autoimmune Disease in Dogs
The exact cause of canine autoimmune disease is not clear. However, it is widely believed that certain factors contribute to the development of autoimmune disease in dogs.
Some of these factors include:
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- Genetics: As some breeds of dogs are more prone to the development of certain autoimmune disease (e.g. German Shepherds are predisposed to
systemic lupus than other breeds), it is believed that genetics is one of the factors that contribute to the development of some types of autoimmune disease.
- Over-vaccination: Some veterinarians believe over-vaccination, especially if multivalent modified-live vaccines are used, can overstimulate
the immune system, causing some autoimmune disease to develop in dogs.
- Certain drugs: Certain drugs, such as antibiotics and corticosteroids, may alter the molecular appearance of some cells, making them look "foreign",
thus triggering the immune system to attack such cells.
- Toxins: Some veterinarians and immunologists also argue that toxins such as environmental pollutants or food preservatives such as ethoxyquin (an
antioxidant found in most dog foods) can trigger autoimmune disease in dogs.
Dog Immune System and Autoimmune Disease
As you can see, canine autoimmune disease comes in different forms and causes different symptoms depending on the parts of the body affected. However, no matter the form,
autoimmune disease is a result of the dog's immune system going haywire. Although it is impossible to completely prevent autoimmune disease to occur in dogs, it is at least a
good precaution to take care of the dog's immune system by keeping it strong and functioning properly.
Some ways to maintain a healthy immune system in dogs include feeding the dog a natural diet
with no preservatives and addictives.
Supplements that are beneficial to the dog's immune system should be given. One such beneficial supplement is
antioxidants. Antioxidants are minerals and vitamins that
can help the immune system to get rid of free radicals and reduce oxidative stress without directly stimulating an immune response.
Common antioxidants include selenium, alpha-lipoic acid, coenzyme Q10, carotenoids, and vitamins A, C and E.
In addition to a healthy diet, removing toxins such as environmental pollutants is equally important in the prevention of autoimmune disease in dogs.