Immune Mediated Hemolytic Anemia In Dogs – Everything You Need To Know

Immune-mediated hemolytic anemia (IMHA) is the most common reason for dogs’ anemia. However, proper knowledge of its symptoms, identification, and early treatment contribute to your dog’s survival.  

What is Immune-Mediated Hemolytic Anemia in Dogs?

Immune-Mediated Hemolytic Anemia or IMHA in dogs occurs when your pet’s immune system fails to differentiate between his red blood cells and foreign cells. Thereby, his immune system attacks and destroys his red blood cells. This decreases red blood cells, leading to anemia and inflammation throughout your pet’s body. Since your pet’s immune system is involved in destroying RBCs, this condition is called Immune-Mediated Hemolytic Anemia or Autoimmune Hemolytic Anemia (AIHA). 

How Are Red Blood Cells Normally Removed from the Body?

The bone marrow produces the RBC, reaching the blood circulation to deliver oxygen and remove carbon-di-oxide. Further, these cells must be soft and supple to perform their function. However, the spleen destroys these cells when they become aged, damaged, or have been infected. Once destroyed, their proteins are broken down into amino acids while the iron is sent to the liver to convert to bilirubin.   

What Happens During IMHA?   

If your dog suffers from IMHA, his immune system removes too many RBCs. As a result, his system suffers from the following consequences:

• A decrease in the number of RBCs leads to a lack of blood, weakening your pet.
• The spleen enlarges as it processes more damaged red blood cells. 
• The liver is affected as it has to process overwhelming amounts of bilirubin which leads to the development of jaundice or icteric. This condition can cause your pet’s tissues to turn yellow or orange.
• The increased number of hemoglobin prevalent in the bloodstream can damage the kidneys. 
• The antibody-coated red blood cells stick to each other forming small clots which can block blood vessels, compromising circulation and creating inflammation. 
• Therefore, the tissues lack oxygen, accumulating waste gas.

Is IMHA in Dogs a Complicated Issue?

Due to the above complications, this life-threatening condition results in a 20-80 percent mortality rate.

Causes of Immune-Mediated Hemolytic Anemia in Dogs 

Immune-mediated hemolytic anemia occurs due to:

Production of defective antibodies

The primary reason a dog is affected by IMHA is when its immune system manufactures an incorrect antibody that destroys its red blood cells. 

Underlying diseases, toxins, or bites

An underlying disease or a toxin can alter the surface of your pet’s RBCs. Your pet’s immune system detects this alteration as a foreign invasion and attacks to destroy it. Other reasons for your pet’s immune system to be triggered are:

• Cancer
• Infection 
• Blood parasites such as Babesia 
• Drug reactions
• Snakebites 
• Chemicals or different allergic reactions
• Toxins
• Bee stings

Symptoms of Immune-Mediated Hemolytic Anemia in dogs 

Pets suffering from IMHA will experience the below symptoms. Hence, take them to the vet right away if you notice any of them as different dogs experience a range of symptoms:

• Weak
• Shallow or rapid breathing
• Faster than normal pulse
• Lack of appetite
• Weight loss
• Black/Tarry stools
• Eating dirt
• Lethargy or depression
• Dark orange to brown urine
• Pale to yellow skin/gums
• Jaundice (yellow discoloration, especially of the whites of the eyes)
• Tachycardia
• Vomiting
• Tachypnea
• Sometimes fever

Diagnosis of Immune-Mediated Hemolytic Anemia in Dogs 

If there are physical symptoms of IMHA, your vet will begin his diagnostic tests to confirm if your dog is anemic. For this, he will order a:

1. Complete blood count (CBC): This test measures various values in a blood sample. 
2. Packed cell volume test (PCV): This test determines the percent of red blood cells in the sample and helps evaluate the difference in the shape, size, and several cells. 

The above tests will help your vet to suspect if your dog suffers from IMHA. Therefore, your vet might order other tests to determine the cause of the disease:

1. Reticulocyte test: To detect the presence of immature red blood cells in the bloodstream. 
2. Antibody tests such as a Coombs test:  To detect certain diseases.

Other recommended tests to rule out the presence of any underlying conditions are: 

1. Biochemical profile: To evaluate organ function and electrolyte levels. 
2. Urinalysis: Helps to understand kidney functioning and indicates the presence of urinary tract infections. 
3.  X-rays of the chest and abdomen rule out lung and stomach cancer. 
4.  An abdominal ultrasound examination: To rule out cancer in the gut.

Treatment of Immune-Mediated Hemolytic Anemia in Dogs 

The treatment for IMHA varies as per the critical signs your dog exhibits: 

Severe anemia: Life-threatening condition

In case your pet suffers from severe anemia, she requires aggressive treatment. Hence, your vet will order a blood transfusion to stabilize the dog while identifying the inciting cause of the disease. Following this, several tests are performed to determine the cause of the disease. 

If the underlying cause is detected to be due to bites, toxins, or infections 

The treatment focuses on removing the underlying cause with medications such as antibiotics, heartworm treatment, or antidotes.

If the Underlying Cause is Unknown 

If the underlying cause is unknown, your vet will put your dog on immunosuppressive therapy. These medications suppress his overactive immune system. Therefore, some dogs respond to the treatment rapidly.  

Are Some Breeds of Dogs More Prone to IMHA?

Certain breeds are prone to develop IMHA:

• Cocker Spaniels
• Springer Spaniels
• Poodles
• Irish Setters
• Old English Sheep Dogs
• Pitbull Terrier
• Miniature Schnauzer
• Unspayed female dogs and neutered male dogs

Final Thoughts

Summing up, immune-mediated hemolytic anemia is a severe blood disorder that can be life-threatening. This condition is not preventable and carries a mortality rate of 20% to 70% within 1-2 months of diagnosis. Nevertheless, your dog’s liveability is drastically reduced if the bone marrow is affected. You can euthanize your pet if he exhibits severe dehydration and persistent vomiting and does not respond to medical therapies and treatments. On the other hand, your pup can return to her original life if she survives on medications and copes without them. However, you still must carefully monitor as this disease has a relapse rate of 12 to 20%. In any way, early spotting of the symptoms is the key to a successful treatment.