Anemia is defined as a low red blood cell count and can be caused by a number of different processes, including blood loss, red blood cell destruction, and inadequate red blood cell production.
The aforementioned categories of anemia can be caused by trauma, cancer, immune-mediated disease, which is a disease in which the body attacks its own cells or organs, infectious disease, toxins, genetic defects, inflammatory disease, iron deficiency, drug reactions, kidney failure, and generalized chronic (long term) illness.
Because there are so many different types and causes of anemia, there is no gender or age predisposition for anemia. Individual disease processes may be more common in certain age groups and breeds, so it is important to characterize the type of anemia present.
The impact of anemia on your pet will depend on the cause of the anemia as well as the severity of the anemia. Additionally, animals with a sudden onset of anemia may be clinically sicker than animals with chronic anemia. This is due to the fact that animals can become partially adapted to the anemia over time, and may feel relatively good in spite of the anemia.
Depending on the underlying cause of the anemia, your pet may show some or all of these signs. Some pets may not show any signs at all.
Other possible diagnostic tests based on initial findings:
The most important component of treating anemia is treating the underlying disease process that is causing the anemia. If anemia is severe, patients might require a blood transfusion, or multiple transfusions.
Administer all medications as prescribed by your veterinarian. Monitor your pet for pale gums, extreme weakness, anorexia, increased respiratory rate, or recurrence of any of the original clinical signs.
There are no specific means of preventing anemia, since it can be caused by numerous factors.
Anemia can be a primary problem, which significantly affects your pet's well being, or it can be secondary to other disease processes, in which case it might or might not cause important clinical illness. The most common causes of severe anemia in dogs include blood loss and red blood cell destruction. External blood loss is generally caused by trauma. Significant internal blood loss in dogs most often occurs due to either bleeding into the intestinal tract or bleeding into the abdominal cavity.
Vehicular trauma is a common cause of bleeding into the abdomen. This results from damage to the liver and/or spleen and sometimes the kidneys. This type of blood loss cannot be seen, but can be life threatening and will often result in collapse. Tumors associated with the liver and spleen can also cause significant bleeding into the abdomen. A third common cause of bleeding into the abdomen is rat poison ingestion, which inhibits normal blood clotting.
Bleeding into the intestinal tract will often result in the formation of black, tarry stools. This can be secondary to cancer, severely low platelet counts (platelets are the blood cells that aid in blood clotting), or severe inflammatory disorders of the gut.
Red blood cell destruction commonly occurs in dogs due to an immune-mediated disease in which the body destroys its own red blood cells. This type of anemia is called hemolytic anemia. Hemolysis may also be caused by cancer, exposure to certain drugs, vaccine reactions, heavy metal toxicity (zinc, copper), and infectious diseases, several tick-borne diseases in particular.
Any chronic illness can cause anemia. This type of anemia is usually mild to moderate, and does not significantly impact the pet in most cases.
As discussed, there are many causes of anemia and therefore many different clinical signs. Other diseases that may cause signs of generalized weakness, collapse and increased respiratory rate include:
A thorough history and physical exam are important in order to establish a diagnostic plan. Because there are so many causes of anemia, historical and physical clues are important to narrow down the possible diagnoses. The length of illness may allow estimation of how long the anemia has been present. Travel history, exposure to ticks, current or recent medications, vaccine history, and past medical problems may provide important information. Evaluation of the mucous membranes (gums, anus, vulva or penis) will often reveal pallor, which is suggestive of anemia. Abdominal distension and intra-abdominal fluid can often be palpated by an experienced clinician, which may lead to a diagnosis of blood loss into the abdomen. An enlarged spleen may be present with various types of anemia, and this can often be palpated as well.
Additionally, careful examination for evidence of bruising or bleeding into the gut, eyes, nose, mouth, and ears can all be evaluated by the veterinarian. Yellow discoloration of the membranes or skin can be a marker of red blood cell destruction. This occurs due to rapid production of pigments that are a normal by-product of red blood cells. When cells are rapidly destroyed, the body becomes overwhelmed and the pigment (bilirubin) levels in the blood become elevated, imparting a yellow color to tissues.
Additional tests include:
Regenerative anemia is caused by either blood loss or hemolyis (red cell destruction). Non-regenerative anemia is seen with either acute (very sudden) anemia of any cause, bone marrow disease, iron deficiency, or bone marrow suppression secondary to chronic disease or kidney failure. Performing a reticulocyte count is therefore very useful in narrowing down the causes of the anemia.
Discussing specific therapies for the multiple causes of anemia is beyond the scope of this article. Articles on individual diseases should be referenced for more information. However, treatment in general may include the following:
Optimal treatment for your pet requires a combination of home and professional veterinary care. Follow-up can be critical, especially if your pet does not rapidly improve.