"Case of the Month" – February 2017
Bella, a 5-year-old female pit bull terrier, was acting lethargic a few months ago and then produced dark urine and was icteric (jaundice-like). Her owner Carol, a veterinarian and UC Davis alum, knew something was wrong and ran blood tests on Bella. The tests indicated extremely low red blood cell (RBC) counts, and Carol suspected a case of immune-mediated hemolytic anemia (IMHA). IMHA can be a fatal disease, as it causes a dog’s immune system to destroy its own RBCs (which carry oxygen to the cells and pick up carbon dioxide).
Over the next two days, Bella received two transfusions of packed RBCs and was started on treatment to suppress her immune system, but she did not respond well to the treatment. Carol knew it was time to seek alternative treatment options with the specialists at the UC Davis veterinary hospital.
After admission to UC Davis, the Emergency and Critical Care Service worked with the Transfusion Medicine Service to administer two additional packed RBC transfusions to Bella, after her RBC count dropped significantly overnight from her admission figure of 22 percent to 12 percent. Dogs should normally have a count of more than 40 percent.
Luckily for Bella, UC Davis operates the largest veterinary blood bank in the western United States. Bella’s transfusions were swiftly performed with blood from the hospital’s local canine donor base. Several times a week, locally-owned dogs visit the hospital to donate blood. The blood is then processed and stored in an extensive on-site bank, allowing the hospital to perform more than 600 transfusions per year.
Since there was so much breakdown of RBCs, despite appropriate treatment, veterinarians with the Internal Medicine Service discussed with Carol proceeding with the use of therapeutic plasma exchange (TPE). TPE has made headway in veterinary medicine over the past few years as a state-of-the-art blood purification procedure, joining the ranks of hemodialysis and hemoperfusion. TPE is an apheresis (removal of impurities from blood) treatment in which plasma contaminated with damaging (pathogenic) antibodies, toxins or abnormal proteins is separated from the patient’s flowing blood and exchanged with donor plasma that is returned to the patient to render the patient less susceptible to or free from immunologic attack or other pathologic processes.
Unlike hemodialysis or hemoperfusion (in which impurities are removed from intact blood), TPE separates the blood into its component fractions, and the pathogenic fraction is removed or specifically altered prior to return to the patient. The remainder of the (purified) blood is returned to the patient. The pathologic component is delivered to a waste bag and discarded.
Bella received three TPE treatments while at UC Davis. After her first day of treatment, she did not need any further blood transfusions. On her sixth day of hospitalization, her RBC count had increased to 32 percent and her reticulocyte (new RBC growth) count continued to show a strong regenerative response to the anemia. Bella was healthy enough to be discharged that day, but still remained at risk of forming blood clots, which can be a cause of significant mortality in IMHA patients. As such, she was also prescribed anticoagulant medications. Additionally, to help suppress her immune system from attacking her own cells further, Bella was placed on an immunosuppressive therapy of medications.
Two weeks after discharge, Bella showed a positive recovery at her recheck appointment. She was bright and her RBC count was at 40 percent, within the normal range. She will need to continue immunosuppressive therapy for at least 4-6 months to keep her in complete remission of IMHA.
Bella’s success is one of many examples at UC Davis that shows TPE to be emerging as an innovation in veterinary therapeutics for IMHA and should be considered a first-line, rather than a delayed, therapy for animals with severe IMHA unresponsive to initial blood transfusions or medical therapy.
“We are very grateful for everyone at UC Davis,” said Carol. “Her TPE treatments were lifesaving, and everyone treated her with loving care.”
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