What is immune-mediated hemolytic anemia (IMHA)?

Immune-mediated hemolytic anemia is a condition where the immune system attacks and destroys the body’s own red blood cells. This can rapidly lead to severe anemia, affect the liver and kidneys, and cause blood clots (i.e., thromboembolism) and other life-threatening complications. Primary IMHA, which represents the majority of cases in dogs, does not have an apparent cause. For secondary IMHA, possible immune system triggers include medications, blood parasites, tick-borne diseases, bee stings, snake bites, or cancer.

What are common IMHA signs in dogs?

Early signs include:

• Poor haircoat

• Decreased appetite

• Depression

Intermediate to advanced signs include:

• Weakness

• Fever

• Bloody vomit or diarrhea

• Dark brown or red urine

• Pale or yellow-tinged gums

• Abdominal pain

• Panting

• Tremors

• Collapse

How is IMHA managed in dogs?

IMHA can have a high mortality rate during the first two weeks of treatment. Most dogs with IMHA will require hospitalization, blood transfusions, immunosuppressants, and antithrombotic medications. Refractory IMHA cases can require multiple blood transfusions, or surgery to remove the spleen. Any underlying disease should be identified and treated. Dogs will need medication for several months, with regular veterinary visits and diagnostic monitoring. Discussing a personalized management plan with your veterinarian is important for the best outcome for your dog.

What is the prognosis for dogs with IMHA?

The prognosis for dogs with IMHA depends on their condition at the time of diagnosis and their treatment response. After the initial crisis, up to 75% of dogs with IMHA can have a good quality and length of life. However, there is a 15% chance of relapse in the first five years.

Management tips for dogs with IMHA    

At-home needs include:

• Easy access to food and water, and a comfortable location

• Strict consistency with medications—do not stop unless directed by your veterinarian

• Monitoring for changes in gum color, energy level, appetite, thirst, urination, and defecation

In a crisis situation:

Contact your veterinarian immediately if your dog becomes lethargic, is unable to walk, has abnormal gum color or difficulty breathing, or suddenly collapses.