Immune mediated hemolytic anemia (IMHA), which used to be called autoimmune hemolytic anemia (AIHA), develops when a dog’s immune system attacks and destroys its own red blood cells. This immune response is supposed to be directed against invaders like disease-causing bacteria or cancerous cells, but when it goes awry it can cause serious illness and even death.
Who Is Most at Risk?
Immune mediated hemolytic anemia most commonly affects middle-aged, female dogs. Some breeds (e.g., cocker spaniels, springer spaniels, miniature poodles, Irish setters, dachshunds, bichon frises, and old English sheepdogs) are genetically predisposed. In some cases, the disorder may be initiated by infections, cancer, medications, or vaccination, but most of the time, no underlying trigger can be identified.
Common Symptoms of IMHA
Red blood cells are responsible for carrying oxygen throughout the body. When they are destroyed, dogs will typically have the following symptoms:
- rapid or deep breathing
- pale or yellow mucous membranes
- weakness and lethargy
- dark urine
- loss of appetite
None of the symptoms typically associated with IMHA are unique to this disease. Owners who think that their dog could have IMHA should take their pets in to a veterinarian immediately for diagnosis and treatment.
Diagnosis and Treatment
After performing a physical exam, your veterinarian will run blood work and a urinalysis to rule out other potential causes of a dog’s clinical signs. If the results point towards IMHA, he or she may also want to run a Coombs’ test (a particular type of blood test), which can help confirm the diagnosis.
Aggressive treatment for IMHA should begin as early in the course of the disease as possible. Hospitalization is necessary so that dogs can be closely monitored and receive intravenous fluids, medications to suppress the immune response (e.g., prednisone, cyclosporine, and/or azathioprine), oxygen therapy, and sometimes blood transfusions and medications to reduce the formation of blood clots. If an underlying cause for IMHA can be identified, it will also need to be addressed.
Once a dog’s condition is stable, he or she can go home for continued treatment. The veterinarian will gradually decrease the doses of immunosuppressive drugs over the course of a few months while closely monitoring the dog’s red blood cell counts for a relapse. Some pets eventually come off all of their immunosuppressive drugs while others require life-long treatment.
Immune mediated hemolytic anemia is a potentially fatal disease, but many affected individuals go on to live normal lives if they can make it through the initial crisis.