Immune-Mediated Hemolytic Anemia in Cats

IMHA is characterized by fatigue, pale-colored gums, and an increased heart and respiratory rate. Because IMHA could be fatal if left untreated, bring your cat to a veterinarian as soon as you spot symptoms.

Immune-mediated hemolytic anemia (IMHA) also goes by the name auto-immune mediated hemolytic anemia (AIHA). This condition occurs when your cat’s immune system mistakenly destroys red blood cells, which are responsible for transporting oxygen throughout the body. When your cat’s tissues do not receive enough oxygen, they begin to slowly die off.

Once symptoms appear, they may begin to worsen quickly, so it’s important to pay close attention to your cat and bring him to a vet right away if you observe anything unusual. Some of the symptoms you may notice include:

• Pale-colored gums
• Lethargy
• Vomiting
• Increased heart rate
• Increased respiratory rate
• Loss of appetite
• Weakness

IMHA can be diagnosed as either primary or secondary. The cause of primary IMHA is idiopathic, meaning it is unknown. Secondary IMHA occurs when there is another medical condition that is affecting your cat’s red blood cells. Your cat’s immune system will mistake the altered red blood cells for invaders and attack them. Some medical conditions that can cause secondary IMHA include cancer, infections, parasites, exposure to toxins, or reactions to medications.

Bring your cat into a veterinarian as soon as you spot symptoms of IMHA. Let your vet know what symptoms you have observed and when they first began. Anemia cannot be diagnosed based on observable symptoms, so the vet will need to perform a series of tests to determine the issue.

First, the vet will conduct a complete blood count test, which will give the vet a better picture of the cat’s overall health. This test will show the vet if there is a lower number of red blood cells present. Then, the vet will most likely look at a sample of the blood under a microscope to analyze the size and shape of the existing red blood cells. Cats with IMHA will not only have a lower number of red blood cells, but they will also have abnormally shaped cells that can be observed through a microscope. A reticulocyte count, which is a test that shows the vet how many new red blood cells are being made, may also be performed.

Once the vet completes this test, he will be able to identify anemia, however, he will still need to perform other tests to determine the cause. Your cat will most likely undergo urinalysis, blood chemistry profile, and feline immunodeficiency virus testing as the vet tries to determine if the IMHA is primary or secondary.

The vet will prescribe corticosteroids, which will prevent the immune system from continuing its attack on the red blood cells. Some vets will also prescribe additional immunosuppressive drugs such as azathioprine if they do not believe the corticosteroids will be enough to manage the condition. Blood clotting can occur as a result of IMHA, so the vet may also prescribe a blood thinner to prevent clots from forming. If your cat’s condition is life-threatening, the vet will need to perform an emergency blood transfusion. 

If your cat has been diagnosed with secondary IMHA, the underlying condition will also need to be treated. For example, if an infection or parasite is causing the IMHA, the vet will administer antibiotics or medication to eliminate the parasites from your cat’s system. 

Your cat may also need supportive care while he is in the vet’s office to stabilize his condition. This could include the administration of IV fluids to prevent dehydration.

The vet will need to frequently check your cat’s condition to see how his body is responding to medication, so plan on bringing your cat into the vet’s office several times after the initial visit. 

Be sure to closely follow the vet’s instructions when it comes to administering medication since one missed dose could cause a major setback in your cat’s condition. You should allow your cat to rest while he recovers. Anemia will make your cat feel weak and tired, so he should not be forced to participate in strenuous activity until your vet says so. 

Also, speak to your vet about what kind of diet your cat should be fed. It’s important he is given a well-balanced diet to help him regain his strength. 

Unless your cat’s IMHA is caused by a condition such as cancer, he will most likely make a full recovery.