What Causes Anemia in Dogs?

Did you know dogs can get anemia just like humans? It’s true! And depending on the cause and severity, it can be just as serious, if not more.

Unfortunately, anemia can be the result of another underlying medical condition and as you’ll see in this post, determining the cause is always the first thing a veterinarian will have to do before they can treat the dog. This post is going to go over the many potential causes that your veterinarian will check for and hopefully give you a better idea of what to expect should your dog be diagnosed with anemia.

What is Anemia?

Anemia is not actually a specific disease, but rather a symptom of another disease process or condition. It is a medical term that involves the reduction of circulating red blood cells, hemoglobin, or both.

Hemoglobin is a protein inside of red blood cells which delivers oxygen to the cells and tissues of the body in healthy dogs, but anemia will reduce the oxygen levels in affected dogs. Because of the effects of anemia, dogs that have the disease will have a lower-than-normal count of red blood cells and hemoglobin. Red blood cells also remove carbon dioxide from the dog’s body when they function properly.

Healthy dogs will produce red blood cells in their bone marrow, which is then released into circulation. As the red blood cells age or become damaged, the body will naturally remove them from circulation and will recycle them to form new cells. When anemia is present, less red blood cells will be circulating, as they are either lost during circulation or there is a decrease in production in the bone marrow.

Therefore, when a dog has autoimmune hemolytic anemia, it actually means that their body is attacking itself and destroying its own red blood cells. Dogs with anemia will still produce red blood cells in their bone marrow, however, they have a short lifespan when they are released into circulation.

An anemic dog’s immune system will actually mistakenly flag new red blood cells as intruders and will destroy them. The disease causes the body to think that red blood cells are a virus or infection and the immune system will eradicate it.

The red blood cells are either taken out in the blood vessels in a process called intravascular hemolysis or circulated through the liver and spleen and destroyed in extravascular hemolysis. Dogs that have extravascular hemolysis will generally have a more favorable prognosis. In either situation, the hemoglobin will be released in excess levels, causing the liver to be overworked trying to break it down.

When the red blood cell level falls below normal, or they no longer function properly, the dog’s anemia will be quite serious and a real medical concern. If it, and the underlying cause, are not addressed quickly, it could be fatal. Having the proper amount of functional red blood cells is vital to your dog’s health.

What Causes Anemia in Dogs?

There are many potential causes of autoimmune hemolytic anemia. The two forms of AIHA are primary and secondary anemia.

When a dog has primary anemia, its immune system will produce antibodies that attack its own blood cells. Primary anemia is the most common form of anemia in dogs, at an estimated 75 percent of all dogs with AIHA. Unfortunately, the cause of primary anemia in dogs is not yet known. This means your veterinarian will diagnose primary anemia by ruling out all other potential causes that occur in secondary anemia.

The underlying disease or toxin modifies the surface of the dog’s red blood cells in secondary anemia. The immune system then will consider the altered red blood cells to be intruders and will destroy them. When too many red blood cells are destroyed and the bone marrow can’t keep up with production to replace them, the dog becomes anemic.

Secondary autoimmune hemolytic anemia can be caused by several different underlying diseases and conditions, and a low count of red blood cells can also be caused by blood loss, low production of new red blood cells, and the destruction of red blood cells.

Let’s take a look at the many possible causes of secondary anemia.

Canine cancer is the most common cause of secondary anemia in dogs. Cancer may even lead to bleeding into the gastrointestinal tract of from a tumor.

Other causes of anemia are typically broken down into diseases that cause blood loss, those diseases that cause the red blood cells to break down or destruct (hemolysis), and diseases that suppress the bone marrow to decrease the production of red blood cells.

The diseases and conditions that may cause blood loss in dogs include:

  • Any trauma or injury to a dog’s blood vessels or damage to its internal organs which will cause persistent bleeding. Can be the result of something like being hit by a car.
  • A condition called Babesia, which involves a severe infestation of blood-sucking parasites, such as fleas, ticks, whipworms, and hookworms
  • Tumors of the intestinal tract, kidneys, urinary bladder, and spleen
  • Internal gastrointestinal bleeding, which may result from disease, inflammation, or certain medications such as nonsteroidal anti-inflammatory drugs
  • Diseases that prevent the dog’s blood from clotting properly like von Willebrand’s Disease.

Other causes of anemia involve the destruction of red blood cells within the body, also known as hemolysis. These causes may include:

  • An autoimmune disease, most notably immune-mediated hemolytic anemia (IMHA or AIHA)
  • Blood parasites (particularly tick-borne infections, such as Lyme disease or ehrlichiosis)
  • Exposure or consumption of chemicals or toxins, such as rat poison, lead poison, zinc, onions, garlic, etc.
  • Cancer

There are also several causes of anemia that suppress the bone marrow, causing the dog’s red blood cell production to diminish. The causes of anemia related to decreased red blood cell production may include:

  • Severe, long-lasting diseases, such as kidney or liver disease
  • Bone marrow disease
  • Poor nutrition that results from nutritional imbalances
  • Exposure to certain medications that suppress red blood cell production
  • Autoimmune disease
  • Hypothyroidism
  • Reactions to chemicals or toxins
  • Cancer

Other conditions that can cause anemia but don’t necessarily fit into any of these categories include drug reactions to certain canine vaccines and antibiotics, general bacterial infections, snake bites, bee stings or other similar allergic reactions, Cushing’s disease, infectious diseases like