Hemolytic Anemia in Dogs
Dr. Leah Cohn
Diagnosis In-depth Your veterinarian will begin by asking detailed questions about what you have noticed that is out of the ordinary, and when these changes began. Also expect questions about your pet's diet, elimination habits and the color of the stool and urine, any medications, including herbal supplements, your pet may be receiving, and when the most recent vaccinations were given.
Some diagnostic tests are considered essential to the evaluation of hemolytic anemia. Other tests may be essential to an individual animal, as indicated by the results of the animal's history, the physical examination, or preliminary test results. Expect the following to be performed in all cases of hemolytic anemia.
Your veterinarian will complete a physical examination. This will include looking for evidence of bleeding, evaluating gum and eye color (pale gums are found in all types of anemia, but a jaundiced appearance suggests hemolysis), listening to the heart and lungs, and palpating for swellings or organ enlargement.
A complete blood count (CBC) includes both a count of the various blood cell types, and an evaluation of the shape and size of the blood cells. It may also show parasites infecting the red cells.
A packed cell volume (PCV), or hematocrit, is a simple measure of red blood cells. Although a complete blood count will be necessary, because a PCV is a very quick, simple, inexpensive test, it is often performed while waiting for the CBC, or to follow changes in the red cell count on a daily basis.
A serum biochemical profile will be performed to evaluate organ function and the balance of salts in the body. This simple blood test may provide clues about the cause of anemia.
A urinalysis detects byproducts of red blood cell breakdown in the urine, as well as assessing kidney function.
The following tests are indicated in many, but not all, cases identified as having a hemolytic anemia.
A Coombs test uses a small amount of the animal's blood to look for evidence that the immune system is causing the red cell destruction. Antibodies are normally produced by the immune system to attach to and destroy germs. For unknown reasons, sometimes the immune system begins to make antibodies that attach to the red blood cells instead of germs. The Coombs test looks for antibodies attached to red blood cells, and is particularly useful in the diagnosis of immune mediated hemolytic anemia (IMHA).
Antinuclear antibody (ANA) tests may be performed to look for further evidence of a misdirected immune system. A disease called systemic lupus erythematosus (SLE) is one cause of this misdirection, and an ANA test helps in the diagnosis of SLE, but does not specifically test for IMHA.
Radiographs (X-rays) may be taken to look for evidence of metallic objects like pennies in the animal's stomach, or for evidence of enlarged or twisted organs. In addition, cancer sometimes triggers the immune system to destroy red blood cells, so radiographs may prove useful in looking for evidence of cancer in the animal's chest or abdomen.
Ultrasound utilizes sound waves to form a picture of the internal organs. This test may be used in certain settings to determine the cause of hemolytic anemia. For instance, and ultrasound picture of the spleen may show twisted blood vessels, or an ultrasound picture of the heart may show a mass of heartworms stuck together blocking the flow of blood into the heart. This test may require referral to a specialist.
Specific tests may be indicated to look for infections of the blood. These usually involve submitting a blood sample to a special laboratory. Blood parasites are often visible under a microscope, but not always. Special blood tests may be needed to identify some of the hidden germs or parasites.
Other tests may be indicated in a given pet. For instance, a genetic test may be used in a young, purebred dog suspected to have a hereditary cause for hemolytic anemia.
One or more of the diagnostic tests described above may be recommended by your veterinarian. In the meantime, treatment of the symptoms might be needed, especially if the problem is severe. The following nonspecific (symptomatic) treatments may be applicable to some, but not all pets with hemolytic anemia. These treatments may reduce severity of symptoms or provide relief for your pet. However, nonspecific therapy is not a substitute for definite treatment of the underlying disease responsible for your pet's condition.
Blood transfusions may prove life saving. Either fresh blood or a concentrate of red blood cells may be administered through an intravenous catheter. This transfused blood enables oxygen to be delivered to the tissues. Unfortunately, without stopping the cause of hemolysis, the newly transfused cells will themselves be destroyed.
Artificial blood products may be used in place of real blood transfusions. These are not completely man-made, but are derived from components of cow blood.
Because immune system destruction of the blood is the most common cause of hemolytic anemia, animals will often be treated with corticosteroids to suppress the immune system. Corticosteroids, such as prednisone, are intended to slow down the immune system's attack on the cells. Treatment of immune mediated hemolytic anemia (IMHA) may require additional immunosuppressive drugs in order to control destruction of the cells.
Intravenous fluids may be indicated, whether or not the animal receives a blood transfusion. This can support the animal during other treatments, and lessen the likelihood of complications from hemolysis.
Other treatments depend on the correct identification of the cause for hemolysis. For instance, if small, coin-shaped pieces of metal are seen in the stomach on x-rays, these will need to be removed either with an endoscope (a fiberoptic tube passed through the mouth into the stomach) or via surgery. Infectious causes of hemolytic anemia may respond to drug therapy.