IMHA in dogs stands for Immune-Mediated Hemolytic Anemia in dogs. It is a common life-threatening disease in dogs and it is a rare condition in cats. In this disease process, the dogs’ immune system attacks its RBCs and destroys them. It causes anemia in dogs. Anemia is generally defined as low circulating Red Blood Cells in the blood. It is generally categorized into three types.
- Low production of RBCs
- Due to blood loss like internal or external bleeding
- Due to the breakdown of RBC, IMHA falls into this category of anemia.
Without adequate Red Blood Cells (RBCs), the pet may be lethargic, and anorectic and blood oxygen levels may drop. The mortality rate is high in Immune-Mediated Hemolytic Anemia (IMHA) patients without a proper treatment plan.
These patients may need a long stay in the vet clinic on supportive medications, intravenous fluid therapy, blood transfusion, etc.
Which breed is affected mostly with IMHA?
All breeds can be affected, but IMHA is more common in Cocker spaniel, Irish setter, English springer spaniel, Old English sheepdog, Doberman pinscher, collies, miniature pinscher. Most common in young to middle-aged dogs.
How did my dog get IMHA?
A definitive cause for IMHA is difficult to find out, but still, we can categories IMHA causes into two categories.
- Primary or idiopathic Immune-Mediated Hemolytic Anemia (IMHA)
- Secondary Immune-Mediated Hemolytic Anemia (IMHA)
In primary Immune-Mediated Hemolytic Anemia (IMHA), the pet’s immune system destroys its RBCs. An antibody-mediated RBC destruction mechanism without any involvement of external factors is responsible for it. It is also called Autoimmune Hemolytic Anemia. The majority of IMHA cases are due to the primary IMHA. In secondary IMHA, external factors play an important role in triggering a dog’s immune system.
Following a few factors may be responsible for secondary IMHA.
- Certain drugs and chemicals like Penicillin, Acetaminophen, Sulfas, Methimazole, Zinc, anticonvulsants, and many more.
- Certain type of cancers
- Various types of Vaccines
- Common allergies, insect bite, Snakebite
- Blood infections like Ehrlichiosis, Babesiosis, etc.
Common causes of IMHA in Cats.
- Hereditary in some breed
- Feline leukemia virus
- Feline immunodeficiency virus
- Mycoplasma infection
- Incompatible blood transfusion
- Cytauxzoon infection
- Toxins (zinc, copper, onion, methylene blue, etc)
- Drug reaction
What are the symptoms of IMHA in Dogs?
Symptoms of IMHA are quite variable and may be confused with other common dog diseases. They may include some or all of the following:
- Lack of appetite
- Breathing difficulty due to anemia
- Pale mucous membrane due to low RBC count
- Jaundice due to intravascular hemolysis
- Brown urine due to extravascular hemolysis
- Black stools
- High heart rate
- Abdominal pain and fever in some cases.
How is IMHA diagnosed in dogs?
The diagnosis of IMHA is a challenging and cumbersome process. But the following steps and procedures may help in the diagnosis and confirmation of IMHA.
- A thorough history including vaccination, toxic exposure, travel history, ongoing medication, etc.
- Physical examination
- Different types of Blood tests are done by your veterinarian to reach any conclusion.
- Complete blood count ( CBC), in CBC, may see anemia, high reticulocyte count, and neutrophilia.
- Chemistry: may see high bilirubin, high BUN, high Creatinine, increase in liver enzymes, electrolyte imbalance in the blood.
- X-rays are commonly done to rule out any tumor or other concurrent disease.
- The stool test is done to see any parasites in the stool
- Urine is tested for UTI and renal functioning
- Blood film screening to see blood parasites and a special type of RBC called spherocytes. Spherocytes on blood film with other symptoms confirm your diagnosis.
- Coomb’s test can be performed to detect Ig antibodies on RBCs.
What is the treatment for IMHA in dogs?
The main goal is to suppress the immune response of the patient with immunosuppressive medications. And also treat underlying disease in secondary IMHA, and to maintain hemodynamic stability. IMHA patients may need extensive care depending on your pet’s condition.
- Immunosuppression can be achieved by glucocorticoids. Initially, give Dexamethasone @ 0.25-0.5 mg/kg IV once daily. Then switch to Prednisone 2 mg/kg orally and taper it slowly over a month.
- Blood transfusion can be done after proper blood typing if PCV drops below 15 % and the pet is in respiratory distress. First blood transfusion is generally safe, but if we have to do a second transfusion, then risks of blood reactions are high.
- In some cases, with a minimum response to immunosuppressive therapy like corticosteroids. Azathioprine @ 2 mg/kg or Cyclosporine @ 4 mg/kg are also used in some case.
- Intravenous fluid therapy is very important and it is given to maintain sufficient tissue perfusion.
- If relapse of IMHA occurs, then splenectomy may be considered.
- Other supportive medications like antacid, antibiotic, and antiemetic should be given with the main treatment protocol.
The prognosis is variable depending upon the severity of the disease, it is fair in mild cases, and guarded in aggressively hemolytic cases. Many IMHA patients can be tapered completely off medications, however, relapses occur unpredictably. Monitoring the patient for control, recurrence, and infection and the general test should be performed at least every 4 months.
Concurrent Diseases and complication with IMHA
IMHA may coexist with other immune-mediated diseases, the most common of which is immune-mediated thrombocytopenia and DIC.
Conclusion: IMHA is a common disease with high mortality in dogs. But the proper treatment, the patient can recover well. The prognosis of IMHA in dogs is variable and dependent upon the underlying cause and concurrent other conditions.
Common questions on IMHA in Dogs:
Is IMHA in dogs contagious?
Generally, IMHA is not contagious. But causative agents can be spread by ticks.
Is IMHA in dogs painful?
It depends upon the cause of IMHA.
Can my dog recover from IMHA?
Recovery is possible.
Some other important articles:
This information is NOT intended as a substitute for veterinary consultation for any of your pet’s diseases. Always consult your veterinarian for a diagnosis and treatment plan.
- Blackwell’s Five-Minute Veterinary Consult: Canine and Feline by Larry P. Tilley, Francis W. K. Smith
- Saunders Manual of Small Animal Practice by Robert G. Sherding and Stephen J. Birchard
- Emergency Procedures for the Small Animal Veterinarian by Signe J. Plunkett
- Merck Veterinary Manual by Susan Aiello
- 100 Top Consultations in Small Animal General Practice by Peter Hill, Sheena Warman, Geoff Shawcross
- Plumb’s Veterinary Drug Handbook by Donald C. Plumb
- Veterinary Emergency and Critical Care Manual, 3rd Edition by Karol A. Mathews
- Veterinary Guide for Animal Owners, 2nd Edition by C.E. Spaulding, D.M.V. Jackie Clay
- Small Animal Emergency and Critical Care for Veterinary Technicians Third edition by Andrea M. Battaglia, LVT, Andrea M. Steele, MSc, RVT, VTS (ECC)