A Veterinary Technician’s Guide to Immune-Mediated Hemolytic Anemia

Immune-mediated hemolytic anemia (IMHA) is a serious and potentially life-threatening condition in which the immune system mistakenly attacks and destroys red blood cells (RBCs). This leads to severe anemia, requiring prompt diagnosis and treatment. As a veterinary technician, understanding IMHA is essential for recognizing clinical signs, assisting with diagnostic procedures, and supporting treatment plans, particularly in cases requiring veterinary transfusion medicine. 

This free vet tech CE guide provides an overview of IMHA, its causes, symptoms, and treatments, along with the crucial role veterinary technicians play in patient care. Let’s delve in... 

Understanding immune-mediated hemolytic anemia (IMHA) 

IMHA occurs when the immune system produces anti-erythrocyte antibodies that bind to RBCs, marking them for destruction. The body then removes these damaged RBCs, leading to anemia. This hemolysis can occur in two ways: 

• Intravascular hemolysis: RBCs are destroyed within the bloodstream, releasing hemoglobin directly into circulation. This can lead to hemoglobinuria, causing a reddish discoloration in urine. 

• Extravascular hemolysis: RBCs are broken down primarily in the spleen and liver, where they are normally removed at the end of their life cycle. Excessive breakdown can lead to bilirubin buildup, resulting in jaundice. 

While both forms of hemolysis contribute to IMHA, intravascular hemolysis is associated with a worse prognosis due to the rapid destruction of RBCs and increased risk of complications. 

Causes and risk factors of IMHA 

IMHA is classified as either primary (idiopathic) or secondary to an underlying condition. 

• Primary IMHA occurs when the immune system targets RBCs without an identifiable trigger. 

• Secondary IMHA develops due to an underlying cause, such as: 

• Infectious diseases (e.g., Mycoplasma spp., Ehrlichia spp.) 

• Neoplasia (e.g., lymphoma, leukemia) 

• Medications (e.g., cephalosporins, carbimazole) 

Since treating secondary IMHA requires addressing the underlying condition, thorough diagnostic testing, including bloodwork, imaging, and sometimes bone marrow biopsies, is necessary before starting immunosuppressive therapy. 

IMHA is more commonly diagnosed in dogs than in cats, with certain breeds being predisposed. Overrepresented breeds include Poodles, Collies, Miniature Schnauzers, and Spaniels, and middle-aged female dogs are at higher risk. 

Recognizing IMHA in veterinary patients 

Early recognition of IMHA is critical for successful treatment. Common clinical signs include: 

• Weakness, lethargy, and exercise intolerance 

• Pale or jaundiced mucous membranes 

• Tachypnea (rapid breathing) and tachycardia (rapid heart rate) 

• Bounding pulses 

• Dark red or port-colored urine (hemoglobinuria) 

Some patients may present with concurrent immune-mediated thrombocytopenia (IMTP), a condition where the immune system also destroys platelets. When IMHA and IMTP occur together, it is referred to as Evans syndrome. These patients may exhibit petechiae (small hemorrhages) or bruising. 

How veterinary technicians assist in IMHA diagnosis 

As a veterinary technician, you play a key role in diagnosing IMHA by assisting with laboratory tests and monitoring patient status. Diagnostic procedures include: 

Blood smear analysis 

• Identifying spherocytes (small RBCs lacking central pallor), which are present in up to 80% of IMHA cases 

• Detecting reticulocytes (immature RBCs), indicating regenerative anemia 

Saline agglutination test (SAGT) 

• Performed by mixing a drop of fresh blood with saline and observing for RBC agglutination under a microscope 

• Agglutination suggests antibody-coated RBCs clumping together, which occurs in 45–89% of IMHA cases 

Coombs test 

• Confirms the presence of anti-erythrocyte antibodies, supporting a definitive IMHA diagnosis 

Packed cell volume (PCV) and total protein (TP) monitoring 

• Helps track disease progression and evaluate treatment effectiveness 

By recognizing abnormal results and monitoring trends, veterinary technicians help ensure early diagnosis and timely intervention. 

Treatment and management of IMHA 

IMHA treatment focuses on suppressing the immune system, managing complications, and providing supportive care. 

Immunosuppressive therapy 

• First-line treatment: Corticosteroids (e.g., dexamethasone IV for hospitalized patients, prednisolone for stable patients) 

• Second-line medications: Cyclosporine and mycophenolate mofetil (used if steroids alone are ineffective or cause adverse effects) 

Blood transfusions in IMHA 

Many IMHA patients require blood transfusions to stabilize their condition until their bone marrow can produce new RBCs. However, transfusions carry risks, including severe reactions. Decisions should be based on PCV levels and overall cardiovascular stability. 

Anticoagulant therapy 

IMHA patients are at high risk for thromboembolic events due to a hypercoagulable state. Clinicians may prescribe an anticoagulant to reduce the risk. 

The role of veterinary technicians in IMHA patient care 

Veterinary technicians are essential to monitoring and supporting IMHA patients throughout treatment. Key responsibilities include: 

• Assessing vital signs: Monitoring heart rate, respiratory rate, and pulse quality to detect deterioration or transfusion complications 

• Preventing complications: Patients on immunosuppressive therapy require strict hygiene protocols to reduce infection risks 

• Ensuring proper IV catheter care: IV catheters should be placed aseptically, monitored for signs of infection, and checked/redressed at least twice daily 

• Providing nutritional and hydration support: Avoiding fluid overload in normovolemic patients and ensuring they receive proper nutrition 

With careful monitoring, veterinary technicians can help improve survival outcomes and patient comfort. 

Advancing your expertise in veterinary transfusion medicine 

Transfusions in veterinary patients are becoming commonplace, making veterinary transfusion medicine a valuable area of expertise for veterinary technicians. You may wish to consider an online veterinary technician certificate course in transfusion medicine.  

You can: 

• Gain in-depth knowledge of transfusion procedures 

• Improve patient care skills in critical cases 

• Open new career opportunities 

If you're looking to expand your expertise, consider enrolling in our race-approved CE program in veterinary transfusion medicine. Designed for vet techs, it’ll cover everything you need to know to be a better nurse to your IMHA patients. 

Conclusion 

IMHA is a complex condition that requires early detection, skilled management, and specialized care. As a veterinary technician, your role in diagnosing, monitoring, and supporting treatment is essential in improving patient outcomes. 

For those interested in deepening their knowledge in veterinary transfusion medicine, a veterinary technician certificate course in transfusion medicine offers valuable training that can advance your career. 

Take the next step - explore our vet tech certificate program in transfusion medicine today!