Anemia

Liaison: Jan Young

Anemia is a decrease in the number of erythrocytes or red blood cells (RBCs) circulating in the blood stream. It is not a disease in and of itself but, rather, is a symptom of a number of diseases. Regenerative anemia can occur while RBCs are still being produced, as a result of loss (bleeding) or increased destruction. Nonregenerative anemia is due to a lack of production of RBCs. Anemia is also classified as either acute (sudden and rapid) or chronic (slow and long standing).

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Red blood cells (RBCs) carry oxygen from the lungs throughout the tissues of the body. They have a normal life span of perhaps 120 days, and as they age, they are removed from the blood stream by the spleen and discarded. The bone marrow constantly makes new RBCs to replace the old ones. Certain diseases and environmental factors can cause the RBCs to be broken down and removed faster than normal, resulting in a need for the bone marrow to work harder. If the bone marrow cannot keep up with the rate of breakdown, anemia can result. In other situations, the underlying problem may be an inability of the bone marrow to make new RBCs even at a normal rate, again resulting in anemia. A third category of anemia is the result of bleeding, either acutely or chronically. When anemia is found in your dog, it is important, as a first step, for your vet to determine which type of anemia is present.

Signs and Symptoms

Acute anemia can result in shock and even death if the blood volume is not replaced rapidly. Signs include rapid heart rate, pale gums, bounding or weak pulse, and low blood pressure. Chronic anemia is more subtle. Common signs and symptoms include easy tiring or panting and rapid heart rate in the absence of strenuous exercise, pale gums, depressed mood and energy level or even lethargy, and decrease in appetite. Jaundice (yellow whites of the eyes) or bruising may be present in certain conditions.

Causes

Causes of regenerative anemia:

Blood loss: external or internal bleeding resulting from injury, parasites, or from rupture of a splenic tumor or other neoplasm.

Hemolysis (break down of red blood cells): Immune-mediated hemolytic anemia (IMHA: see separate discussion), other immune-related hemolysis, metabolic causes, toxins, infections, and certain inherited diseases.

Causes of nonregenerative anemia:

Underproduction of blood cells: nutritional deficiencies, anemia of chronic disease, renal disease, primary bone marrow disease.

Risk Factors

Risk factors for anemia are the risk factors of the various underlying processes that produce the anemia.

Diagnostic Tests

Medical History.
Hematocrit or Packed Cell Volume (PCV) - a quick test for determining what percent of blood is RBCs.
CBC with platelet and reticulocyte count (young RBCs) - Can detect anemia and may give information about the possible cause.
Depending on the results of these tests your vet may then obtain any of a number of special studies including perhaps: blood chemistry or other special blood tests, urinalysis, examination of stool for blood or parasites, xrays, or bone marrow biopsy.

Treatment Guidelines

Note: Treatment of animals should only be performed by a licensed veterinarian. Veterinarians should consult the current literature and current pharmacological formularies before initiating any treatment protocol.

The treatment of anemia is the treatment of the underlying causative condition. If anemia is severe and/or rapid in onset, blood transfusion may be necessary.