🐾 Vet-Approved 2025 Guide: Immune-Mediated Hemolytic Anemia (IMHA) in Dogs and Cats—Urgent Care & Survival 🩸🐶🐱

By Dr. Duncan Houston, BVSc

Immune-Mediated Hemolytic Anemia (IMHA) is a serious, potentially fatal condition in which a pet’s immune system attacks its own red blood cells. Without red cells to carry oxygen, organ failure and death can occur rapidly. Early recognition, aggressive treatment, and long-term monitoring are essential to survival 🆘

🧪 What Happens in IMHA?

• 🩸 Red blood cells are wrongly flagged by the immune system
• 💔 Antibodies coat the cells, marking them for destruction
• 🧬 Cells are broken down by the spleen or burst in circulation (hemolysis)

💥 This leads to anemia, jaundice, kidney strain, blood clots (thromboembolism), and systemic inflammation.

⚠️ Signs of IMHA

• 😴 Weakness or collapse
• 🟠 Orange or brown urine
• 👅 Pale or yellow gums and eyes
• 🌡️ Fever
• 📉 Loss of appetite and rapid breathing

🔬 Diagnostic Testing

• 🧪 Positive Coombs test (antibodies on red cells)
• 🔬 Spherocytes on blood smear
• 🧫 Autoagglutination (clumping red cells)
• 📈 Lactate levels to assess oxygenation
• 🦟 Blood parasite screening (e.g., Babesia, Ehrlichia)

💉 Crisis Treatment Plan

1️⃣ Transfusions

• 🩸 Replaces lost red blood cells and restores oxygen delivery
• ⚠️ May require multiple transfusions due to continued cell destruction

2️⃣ Immune Suppression

• 💊 Prednisone or dexamethasone—first-line treatment
• 💉 Kills immune cells that mark red cells for removal
• ⏳ High doses needed for 4+ months, then taper

3️⃣ Secondary Immune Modulators

• 🧬 Azathioprine (dogs), cyclosporine, or mycophenolate
• 📉 Added if steroid response is inadequate or side effects occur

🩺 Preventing Fatal Blood Clots

• 🧪 Heparin (anticoagulant) or low-dose aspirin
• 💊 Clopidogrel—safer alternative to aspirin + steroids
• 🚫 Avoid anticoagulants in Evans Syndrome (combined IMHA + platelet loss)

📊 Survival & Prognosis

• ⚖️ Mortality rate: 20–80%
• 🔁 Relapse rate: 11–15%
• 📈 Early lactate normalization = higher survival
• 🧬 Most deaths are due to thromboembolism (blocked vessels)

⏱️ Hospital stays average 4–6 days. Monitoring continues for months.

📚 Research Highlights

• 🐶 Cocker spaniels, schnauzers, and unspayed females are predisposed
• 💊 Aspirin + azathioprine enhanced survival in studies
• 🔬 94% of IMHA dogs had spherocytes; 70% had low platelets

💡 Why Did This Happen?

IMHA is often idiopathic (no clear cause) in dogs. Known triggers:

• 💊 Drugs (sulfas, chemo)
• 🦠 Infections or parasites
• 🧬 Cancer (especially hemangiosarcoma)
• 💉 Vaccination timing is controversial; some link to recent vaccines

🐱 IMHA in Cats

Most feline cases are caused by:

• 🦠 FeLV (Feline Leukemia Virus)
• 🧫 Mycoplasma hemofelis (red cell parasite)

🧬 Evans Syndrome

Evans Syndrome is a deadly form of IMHA where platelets are also destroyed. This makes blood clots less likely—but bleeding more dangerous. It has a high mortality rate.

🧠 Conclusion: Don't Delay Treatment

IMHA is a true veterinary emergency. Rapid diagnosis, intensive care, and ongoing management are vital for survival. Pets who survive the first few days and weeks have a good chance with proper long-term therapy 💉❤️

📲 Need Support or Second Opinions?

For help with IMHA diagnosis, treatment plans, or monitoring, visit AskAVet.com or download the Ask A Vet app 📱 for 24/7 expert support.

🩸 With aggressive care and informed guidance, many IMHA patients go on to live long, happy lives 🐶🐱💊