Bella - Auto-Immune Hemolytic Anemia

By: Jennifer Strasser, DVM, DACVIM

“Bella” is a 5-year-old spayed female Springer Spaniel that presented to the Albuquerque Animal Emergency Clinic after two-to-three days of being lethargic and progressively losing her appetite. Her owners also noticed that her urine had recently become very dark in color. When she came in she was very weak, moderately dehydrated, and the skin on her lower abdomen and the whites of her eyes were very yellow in color. Her respiratory rate and heart rate were both moderately elevated, though her heart and lung sounds were normal. On palpation of her abdomen, her liver and spleen were both mildly enlarged and mildly painful. All of her lymph nodes were mildly enlarged.

We performed bloodwork to try to determine why she appeared so icteric (jaundiced). The complete blood count showed that she was very anemic with a hematocrit of 18% (normal range 37-55%). Her white blood cells were mildly elevated at 22.7 (normal range 6-17). Her platelet count was normal. The biochemical profile showed abnormalities consistent with dehydration, a mild elevation in her liver enzymes, and a total bilirubin of 5.7 (normal range 0.2-0.6). A urine sample showed that it was well concentrated (consistent with healthy kidneys in a dehydrated dog) with excess bilirubin.

The combination of the anemia and the high bilirubin showed us that for some reason “Bella’s” body was destroying its own red blood cells. Bilirubin is a byproduct of excessive red blood cell destruction. There are many conditions that can cause this to happen. One possibility includes infections by microscopic organisms that live in or on red blood cells. The body’s immune system destroys the red cells in the process of trying to get rid of the organism. There are also certain medications including some antibiotics, vaccines, and bee stings that have been shown to trick the immune system in to destroying the red blood cells. Lastly, any process that is going on in the body that causes inflammation (ie. pancreatitis) or is abnormal (ie. cancer), can sometimes be shown to confuse the immune system and lead to abnormal red blood cell destruction. Many times, even though we look for the above disease processes, we do not find a cause and then consider the anemia to be an idiopathic or auto-immune hemolytic anemia (a primary problem with the immune system, such as Lupus in people).

To look for some of these underlying causes, we did more blood tests looking for some of the more common infections, chest x-rays, and an abdominal ultrasound to look for hidden infections or cancer. None was found. It is not common for anemic patients to have an elevated respiratory rate and heart rate because the body is trying hard to get enough oxygen to the tissues in the body with the limited red blood cells it has left. The liver, spleen, and lymph nodes can all be enlarged because they are part of the body’s immune system and are swollen with the inflammation and red blood cell production happening throughout the body. The liver and spleen can also be enlarged because they will bulk up to help make extra red blood cells for the body. Because we could not find an underlying cause to treat, the only choice we had was to use medications to suppress her body’s immune system.  We admitted “Bella” to the hospital for IV fluids to help re-hydrate her and gave her a blood transfusion to help her anemia. We started her on a medication called prednisone to try to suppress her body’s immune system. She was in the hospital for 5 days and received two more blood transfusions, but eventually left the hospital feeling much better.

Auto-immune hemolytic anemia occurs as an idiopathic condition (meaning that we can not find an underlying cause) 60-75% of the time. Occasionally with testing we are able to find an underlying cause, which carries a much better prognosis. If you can treat the underlying cause, there is a much better chance of reversing the disease process. When no underlying cause is found, we are left with using very strong medications to try to shut down the immune system. The most common of these medications include prednisone, azathioprine, and cyclosporine. Medications are used for at least six months after diagnosis. On average, when no underlying cause is found, only 60-70% of these patients survives the disease and gets to go home. Of those lucky patients that do get to go home, approximately half of them will have a relapse of their disease within the next two years. The most common complications that lead to death include severe blood clots (these can go to the lungs or brain and cause sudden death), kidney failure (from all of the toxic effects of the byproducts of red blood cell destruction), or financial limitations (blood transfusions and several days of treatment in the hospital all adds up).

References: 

Textbook of Veterinary Internal Medicine, 7th Edition by Ettinger and Feldman   

Small Animal Internal Medicine, 3rd Edition, by Feldman and Nelson

Dr. Jennifer Strasser earned her veterinary degree at the Colorado State University School of Veterinary Medicine and Biomedical Sciences in May, 2001.  Following graduation, Dr. Strasser went to work at a busy private practice in southern California, where she discovered her interest in internal medicine.  Dr. Strasser was then accepted to an internship program at North Carolina State University, followed by a residency in internal medicine at the University of California at Davis.  Dr. Strasser earned her Diplomate status in Internal Medicine from the American College of Veterinary Internal Medicine in July 2006. Dr. Strasser joined Veterinary Specialists of New Mexico in August 2005. She specializes in the diagnosis and treatment of immune-mediated, endocrine and infectious diseases, problems in the upper and lower urinary tract, gastrointestinal tract, and respiratory systems.  She has also assisted the veterinarians at the Rio Grande Zoo with procedures such as ultrasound and endoscopy.