IMHA in Dogs: Symptoms, Treatment, Prognosis

A diagnosis of IMHA in dogs can be scary and overwhelming, but integrative veterinarian Dr. Julie Buzby is here to help. She explains the condition, symptoms, diagnosis, treatment, and prognosis so you know what to expect every step of the way.

I knew something major was going on when I had three back-to-back-to-back missed calls from my friend Carolyn on a Sunday evening. My mind immediately jumped to worst-case scenarios.

I called my friend back and instantly knew from the tremor in her voice that something was, in fact, very wrong. She explained that her sweet Izzie, an 11-year-old Cocker Spaniel with the softest ears, was currently hospitalized at the local specialty clinic.

As we talked, I learned that her dear dog had been more tired than normal for the last week and only ate half of her breakfast that morning. Then she collapsed on her afternoon walk. Carolyn had rushed her to the emergency and specialty clinic, where she learned that her sweet Cocker might have a life-threatening condition called immune-mediated hemolytic anemia (IMHA). Understandably, this experience had shaken my friend to the core and left her with more worries than answers.

Out of that conversation, this guide to IMHA in dogs was born. I hope it helps ease some of your fears and worries if you are walking through an IMHA diagnosis with your sweet pup.

What is IMHA in dogs?

When I am explaining immune-mediated hemolytic anemia in dogs, or IMHA for short, I like to start by tackling this diagnosis one word at a time.

“Anemia” means a low red blood cell count. And “hemolytic” refers to a specific type of anemia where something is actively destroying the red blood cells. In this case, that something is the immune system, which is where the “immune-mediated” portion of the name comes from. (In some situations, you may also hear IMHA called autoimmune hemolytic anemia, which means the same thing.)

Normally, the immune system is supposed to attack invaders like viruses and bacteria. In the case of IMHA, something causes the immune system to malfunction. As a result, it attacks the body’s own red blood cells instead. This attack can either happen in the blood vessels (intravascular hemolysis) or in the liver and spleen (extravascular hemolysis).

How common is IMHA in dogs?

IMHA is one of the most common autoimmune diseases in dogs. Good data on the true incidence of this disease is lacking. But one older paper estimated that up to 1 in 500 dogs might develop this condition. Any breed of dog can get IMHA. However, it tends to be more common in the following breeds:

• Cocker Spaniels
• Poodles
• Springer Spaniels
• Old English Sheepdogs
• Irish Setters
• Collies

What causes IMHA in dogs?

Typically, IMHA is either primary or secondary. Primary IMHA has no discernible underlying cause. Secondary IMHA occurs when another problem triggers the immune system to inappropriately attack the red blood cells.

Primary IMHA

Primary IMHA is what we in veterinary medicine call a “diagnosis of exclusion.” This means the vet must first rule out all the potential triggers listed below. Once he or she does that, what remains is a diagnosis of primary IMHA. Essentially, this means that for no good reason at all, the immune system has started attacking and destroying the red cells.

When I talk to clients about IMHA, one of the most common questions I hear is why IMHA for their dog. I get it because, as humans, we are wired to want answers, especially when something scary happens to someone we love. However, since 60-75% of cases of IMHA in dogs are primary, there is a good chance that you may never know why your dog developed IMHA.

Secondary IMHA

Less commonly, there will be a known trigger for the IMHA. Some of the most common causes of secondary IMHA are:

1. Certain medications and vaccines

Some antibiotics, while well-tolerated the vast majority of the time, are known to be potential triggers for IMHA. The most classic examples are sulfa drugs, cephalosporins, and penicillins. However, don’t let the fear of IMHA stop you from giving your dog antibiotics if they’re recommended by your vet.

Vaccines are also a potential trigger. But this is a much more challenging definitive link to make. It is very important to note that for most patients, the benefit of routine vaccination greatly outweighs the risk of developing a condition like IMHA. Your veterinarian can discuss this with you and help you determine which vaccines are necessary for your dog.

2. Infectious diseases

Almost any infectious disease process can activate the immune system and cause it to malfunction, resulting in an autoimmune disease like IMHA. Some infectious agents spread by fleas and ticks tend to trigger IMHA most commonly. They include:

• Ehrlichia
• Babesia
• Anaplasma
• Bartonella
• Mycoplasma

Additionally, leptospirosis in dogs (a bacterial infection), heartworm disease in dogs, and whipworms are also potential infectious triggers.

3. Cancer

The two most common cancers that are thought to trigger IMHA are lymphoma in dogs and hemangiosarcoma in dogs. However, mast cell tumors in dogs, soft tissue sarcoma, leukemia, multiple myeloma, and bronchoalveolar carcinoma (a type of lung cancer in dogs) may also trigger IMHA.

4. Inflammatory diseases

Diseases that cause inflammation in the body may also cause the immune system to attack the red blood cells. Some potential conditions that fall under that heading include:

• Pancreatitis in dogs (inflammation of the pancreas)
• Inflammation of the bladder due to a urinary tract infection (UTI in dogs)
• Systemic lupus erythematosus (SLE in dogs): an immune-mediated condition where the body attacks multiple tissues in the body, including the red blood cells
• Pyelonephritis in dogs (kidney infection)
• Prostate inflammation (prostatitis)
• Snake bites in dogs
• Bee stings

Can stress cause IMHA in dogs?

There is no consensus on whether stress could trigger IMHA in dogs or not. Veterinarians have reported a potential correlation between some sort of stressor, such as boarding, surgery, changes in the family or household, etc., and IMHA.

However, correlation doesn’t imply causation. In other words, no one really knows for sure if it was a coincidence that the dog experienced a stressful event around the time he or she developed IMHA or if the stressor actually triggered the IMHA.

What are the symptoms of IMHA in dogs?

Symptoms of IMHA come from low red blood cell numbers, the inflammation occurring in the body, and the consequences of red blood cell destruction. They include:

Weakness

Red blood cells carry oxygen, so when there are not enough red blood cells, the organs do not get enough oxygen. This can lead to your dog struggling to get up and walk, moving slowly, or wanting to lie down again after only walking or standing for a short period of time.

Lethargy

Along the same lines, lack of oxygen due to anemia can lead to a lethargic dog. He or she may prefer to lie around rather than engage in normal activities and sleep more than normal.

Fainting or collapsing

More severe anemia in dogs can cause them to collapse or momentarily lose consciousness. If this happens to your dog, seek emergency veterinary care immediately.

Breathing fast

In an attempt to get more oxygen to the tissues, you might notice your dog breathing faster than normal. Your dog may also seem to get short of breath quickly or be working harder to breathe.

Pale gums

Since red blood cells help give the gums their nice bubblegum pink color, pale gums in dogs are a common sign of low red blood cell numbers. The gums may look light pink or, in more severe cases, almost white.

Fever

Because of the overactive immune system and resulting inflammation, dogs with IMHA may run a fever. This means that if you take your dog’s temperature, it may be greater than 102.5° F.

Abdominal pain

IMHA can cause abdominal pain in some dogs. Your dog may have a hunched stance or wince when the abdomen is touched.

Poor appetite

In addition to being painful, IMHA is distressing to dogs due to the weakness, fatigue, and other symptoms. Not feeling well can make your dog eat less than usual or stop eating entirely.

Vomiting

Some dogs with IMHA will start vomiting, and the vomit may contain blood.

Yellowish gums and skin

Affected dogs may have a yellow tinge to the skin, mucous membranes, or whites of the eyes called icterus or jaundice. Plus, they may have dark brown, red, or orange urine. This occurs when bilirubin, a breakdown product of red blood cells, builds up in the body due to red blood cell destruction. (You may be more familiar with jaundice as a consequence of liver disease in dogs, but it can happen independent of liver issues.)

Eating or licking abnormal materials (pica)

Some dogs with IMHA may lick or consume dirt, bricks, rocks, or other non-food items. This behavior is called pica.

Head to the vet if you suspect IMHA

If you are seeing some of the signs above and suspect your dog may have IMHA, it is important to make an emergency vet visit immediately. IMHA can be life-threatening, so the sooner the vet can start treating it, the better.

How is IMHA diagnosed?

Diagnosing IMHA in dogs requires a combination of clinical signs and lab tests that fit the picture of IMHA.

Physical exam

The vet will typically start with a physical exam, paying special attention to indicators of anemia such as:

• Elevated heart rate: The body is trying to get more oxygen-carrying blood to the tissues.
• Heart murmur in dogs: Anemic dogs have thinner blood, which can cause a heart murmur that resolves when the dog is no longer anemic.
• High respiratory rate: Breathing faster is a way for the body to try to compensate for anemia.
• Bounding or snappy pulses: A strong, quick pulse can point to low blood volume or anemia.
• Yellowish or pale gums: Anemia causes pale gums, and icterus causes yellowish gums.
• Prolonged capillary refill time (CRT): Takes longer than normal for the pink color to return to the gums when pressed until they blanch (normal CRT is less than 2 seconds).
• Enlarged spleen and/or liver: The vet may or may not be able to tell that the spleen or liver is larger when palpating the abdomen.

Initial laboratory testing

There are also a variety of blood tests for dogs that can help determine the number of red blood cells, confirm a diagnosis of IMHA, and gather more information about the dog’s overall condition.

Packed cell volume

The vet may sometimes start with a packed cell volume (PCV). This is a rapid blood test that reports the percentage of the blood that is made up of just red blood cells. For a normal dog, the PCV ranges from 35% to 55%. In dogs with IMHA, the PCV will be much lower, often in the teens.

Complete blood count (with reticulocyte count)

A complete blood count (CBC) measures the three main cell lines made by the bone marrow: red blood cells, which carry oxygen; white blood cells, which help with immune function; and platelets, which help clot the blood. With IMHA, the typical result would be a low red blood cell count, an elevated white blood cell count, and normal or low platelets in dogs.

Additionally, the CBC often includes a reticulocyte count. This involves checking for the number of baby red blood cells, called reticulocytes, in circulation. The bone marrow should respond to anemia by ramping up production of new red blood cells and pushing more reticulocytes out into circulation. As a result, dogs with IMHA should have an increased number of reticulocytes if the bone marrow is doing its job.

Blood chemistry panel

A chemistry panel looks at protein levels and can help assess some basic organ functions. The most frequent chemistry panel abnormality in a dog with IMHA is an elevated bilirubin level. This is because bilirubin builds up in the bloodstream when the red blood cells are destroyed. (A urinalysis may also show increased bilirubin in many dogs with IMHA.)

Saline agglutination test

A great way to help diagnose IMHA is a test to look for autoagglutination. It involves placing a drop of blood on a glass slide and mixing it gently with several drops of saline. In a normal dog, everything will mix smoothly and uniformly. However, in many dogs with IMHA, the blood will clump together obviously, and the mixture will be speckled or blotchy.

This happens because antibodies (immune system molecules) on the surface of the red blood cells stick the cells together in a process called autoagglutination. The resulting clumps of red cells are big enough to see with the naked eye. A normal dog does not have these antibodies, which is why the red cells won’t clump together.

Coombs test

Occasionally, the vet will also recommend a Coombs test to check for antibodies on the surface of red blood cells. Since these antibodies are not normally present on red blood cells, a positive result fits with a diagnosis of IMHA.

Blood smear

Your veterinarian may also want to perform a blood smear. For this test, the veterinarian or veterinary pathologist spreads a thin layer of blood out on a slide and examines it under the microscope.

With IMHA, the veterinarian or pathologist would expect to see increased numbers of cells called spherocytes. They are smaller and darker red blood cells that are left behind after the immune system attacks red blood cells and takes a “bite” out of them.

Additional tests to screen for causes of secondary IMHA

As you learned earlier, there are a variety of conditions that the vet needs to look for in order to get to the bottom of why your dog has IMHA. One important step is testing for tick-borne diseases in dogs. Usually, IMHA triggered by a tick-borne infection is the best-case scenario. In these dogs, the IMHA usually responds very well to treatment. And it is unlikely to recur once the underlying infection is taken care of.

Your veterinarian may also discuss chest X-rays and an abdominal ultrasound to look for any evidence of the types of cancer or inflammation that can sometimes trigger secondary IMHA. He or she will also carefully review your dog’s medical history for any recent medications or vaccinations that could be linked to IMHA.

What is the treatment for IMHA in dogs?

Some dogs with suspected IMHA will require initial treatment to get them stabilized while the vet is running the diagnostic tests. Then, once the vet confirms an IMHA diagnosis, he or she will discuss the treatment plan moving forward. Typically, stabilization and treatment involve:

Steroids (dexamethasone and prednisone)

Vets commonly use steroid medications like dexamethasone (injectable) and prednisone for dogs (oral) to suppress the immune system in IMHA patients. Steroids are inexpensive, easy to obtain and administer, and work very well. It is no wonder that they are a part of the veterinarian’s toolkit for almost all dogs with IMHA.

Unfortunately, steroids can also have a lot of side effects. Since IMHA is a life-threatening disease, these side effects tend to be worth the expected benefit, though.

Some of the steroid side effects dog parents should know about include:

• Increased thirst and urination
• Increased panting
• Agitation 
• Lethargy or listlessness
• Weight gain for small to medium-sized dogs
• Weight loss and significant loss of muscle mass for medium to larger breed dogs
• Increased appetite
• Increased risk of other infections (skin infections, UTIs, etc.)
• Thinning of the skin
• A thin or dull haircoat
• Insulin resistance, which may increase the chances of diabetes in dogs or cause issues in an already diabetic dog
• Iatrogenic Cushing’s disease in dogs (Cushing’s disease caused by steroid administration)

Higher doses and longer courses of steroids tend to cause more significant side effects.

Secondary immunosuppressants

If your dog’s case of IMHA seems very severe, or if your veterinarian is worried about more significant side effects from steroids alone, they may decide to add a second medication to suppress the immune system.

The three most common secondary immunosuppressive medications are Atopica® (cyclosporine), mycophenolate, and azathioprine. Each of these medications has a specific set of pros and cons that will be unique to your furry family member. Your veterinarian can determine which one is best for your dog’s situation.

Blood transfusions

Most dogs with IMHA will need at least one blood transfusion to help keep them stable while the medications to suppress the immune system kick in. It can take five to seven days, and sometimes longer, for immunosuppressive medications to halt the immune system’s inappropriate destruction of the red cells. In the meantime, the body will continue to rapidly break down the red blood cells.

Blood transfusions during this period of time are a temporary solution to bring the red blood cell count back up to a safe level. Many dogs need more than one blood transfusion. How fast the immune system destroys the red cells that each transfusion provides will dictate how many transfusions a dog needs.

Plasmapheresis

If a dog does not respond to these more typical first-line treatments, there are still other options to consider. Plasmapheresis is a treatment that has recently shown promise for dogs with IMHA. It removes the fluid portion of the blood, called plasma, which contains the immune components that are inappropriately attacking the red cells.

Then it replaces the “bad” plasma with a transfusion of “good” plasma from a healthy donor dog. This treatment is related to dialysis treatment, and only a limited number of specialty and university hospitals can perform it.

If you are interested in learning more, a 2021 study in the Journal of Veterinary Internal Medicine evaluated plasmapheresis as a treatment option for IMHA in dogs.

IVIG infusions

As another option, the vet can administer a human immune product, IVIG, to your dog over several hours. IVIG works by temporarily clogging up the receptors on the immune cells so they cannot bind to and destroy the red blood cells. Both plasmapheresis and IVIG are expensive treatments. As such, they may be cost-prohibitive for some dog parents.

Anticoagulant or antiplatelet medication

The overactive immune system in dogs with IMHA causes an increased risk of developing dangerous blood clots. Sadly, blood clots to locations like the lungs or the brain are one of the most common reasons a dog with IMHA may not survive. Most dogs with IMHA will take either an anticoagulant or an antiplatelet medication.

The goal is to try to decrease the chances of developing a life-threatening blood clot. The vet may use injectable medications like heparin in the ICU setting. But at discharge, he or she will typically prescribe an oral medication like Plavix® (clopidogrel), aspirin, or Xarelto® (rivaroxaban). 

Doxycycline

The antibiotic doxycycline is effective against most tick-borne infections that can trigger IMHA. Your vet may choose to start your dog on doxycycline for several reasons, including:

• Confirmed tick-borne disease.
• To treat for possible tick-borne disease if you and your veterinarian decide not to pursue tick testing.
• As a way to cover the bases while the results of tick-borne disease tests are pending.

Additional medications and therapies

Some dogs with IMHA can be managed at home from the start. Others are very sick and require hospitalization. If your dog with IMHA is hospitalized, the vet will probably put him or her on IV fluids.

Lots of dogs with uncontrolled IMHA also have a decreased appetite or signs of nausea. If this is the case for your dog, your veterinarian may prescribe anti-nausea medications like Cerenia for dogs (maropitant) or ondansetron.

Long-term treatment of IMHA

Once a dog has a stable red blood cell count and can take oral medications, he or she can come home from the hospital. At this point, most dogs are on a high dose of prednisone, doxycycline, an antiplatelet medication like clopidogrel, and possibly a secondary immunosuppressive medication.

The vet will keep your dog on the higher dose of steroids until the red blood cell count is normal for about three weeks. At that point, he or she will start to taper the steroid dose very slowly. This process often lasts between four and six months and requires careful monitoring of the red blood cell count as the dose of steroid decreases.

It is possible to eventually wean many dogs with IMHA off their medications entirely. However, relapses can occur, so it is important to keep a close eye on your dog. If your dog does start to experience another episode of IMHA, you may see the same symptoms as before. In that case, contact your vet promptly.

What is the prognosis for dogs with IMHA?

The prognosis for IMHA is guarded, especially in the first 10 to 14 days after diagnosis. After that time period, the prognosis is better overall. In general, dogs with secondary IMHA, where the underlying cause is treatable, tend to have a better prognosis than those who have primary IMHA.

The good news is that once a sick dog with IMHA is stable enough to be discharged from the hospital, the overall prognosis is much better. 

Survival rates for dogs with IMHA

Survival rates vary a bit depending on the research paper studied. One study showed that 74% of dogs with IMHA survived to discharge, and 67.7% were still alive 30 days after diagnosis. Another reported the 1-year survival rate to be 50.5%. Factors such as low platelets, low protein, high band neutrophils (a type of immature white blood cell), high bilirubin, high BUN (a kidney enzyme), and high AST (a liver enzyme) may all correlate with a lower survival rate.

Some dogs succumb to dangerous blood clots. For others, the reason for a poor outcome is more complicated. Around-the-clock ICU care and multiple blood transfusions are expensive. In some cases, dog parents reach a very difficult point where they cannot continue treatment due to financial constraints.

IMHA relapses are possible

Studies indicate that 12% to 20% of dogs with IMHA will experience a relapse. If that happens, the vet may treat him or her with another tapering course of immunosuppressive medications.

In some cases, dogs may need to remain on immunosuppressive medications for the rest of their lives to keep their IMHA in remission. In these dogs, the goal is to have them on the lowest possible dose of medication to limit the side effects they experience while still controlling their disease.

What kind of monitoring will dogs with IMHA need?

Dogs with IMHA will need careful follow-up, close monitoring, and repeat bloodwork following their diagnosis. It is important to stay in close contact with the vet and promptly report any changes in your dog. You see your dog every day and know him or her well. That makes you the perfect person to notice when things are a bit “off” with your pup.

How do you prevent IMHA in dogs?

Please take comfort in knowing that there probably isn’t anything you could have done to prevent your dog from getting IMHA. More often than not, there is no identified trigger. And even if there was, plenty of dogs receive the medications and vaccinations or have the diseases or cancers that can be associated with IMHA, but never develop IMHA.

That being said, following your vet’s recommendations about vaccinations and parasite preventives can help decrease the chances your dog will get one of the conditions that can trigger IMHA and help keep your dog healthier overall. Your vet wants what is best for your dog and will weigh the potential risk of IMHA (or other adverse events) with the benefits of the care he or she is suggesting.

Additionally, keeping a close eye on your dog and promptly reporting any changes in behavior or new symptoms to your vet can help you catch problems like IMHA (or the diseases that trigger IMHA) quickly. This won’t prevent them entirely, but it may prevent them from getting out of hand.

You are not alone

I know that an IMHA diagnosis can be scary and the outlook may be uncertain at first, but you don’t need to tackle it alone. There are plenty of people ready to help and support you and your beloved dog.

Your dog’s veterinary team (the ER vets, your family vet, and/or internal medicine specialist) will be with you every step of the way. They are carefully monitoring your dog while hospitalized and will continue to keep tabs on your dog’s progress long term.

If you are feeling overwhelmed or have concerns about your dog, don’t hesitate to contact the veterinary team caring for your dog. It can be helpful to write down a list of questions from the visit (or your online reading about IMHA) and call the vet back once you have gotten a chance to process some of what he or she said. Taking notes during the conversations is a great way to keep it all straight, too.

Additionally, if you need someone to talk to who understands what you are going through, reach out to a friend who has had a similar experience with his or her dog, or join an online support group for parents of dogs with IMHA. (Remember, though, that your veterinarian is the best person to address the medical aspects of your dog’s case.)

You are not alone in your dog’s fight against IMHA.

Have you ever had a dog with IMHA?

Please share his or her story.

This post was originally published on November 11, 2021 and updated on March 30, 2026.