What is Immune-Mediated Hemolytic Anemia (IMHA)?
Red blood cells are important because they contain hemoglobin, which carries oxygen to the body’s tissues. The reduction of red blood cells caused by IMHA directly affects how much oxygen the tissues are receiving. Without the proper amount of oxygen, the body’s organs cannot function normally.
The destroyed red blood cells result in a buildup of hemoglobin, which the liver attempts to “clean” by producing more bilirubin. The excess bilirubin causes patients with IMHA to appear jaundiced.
All breeds can have immune-mediated hemolytic anemia but there are more documented cases in Cocker Spaniels, Labrador Retrievers, Poodles, Irish Setters, Shih Tzu, and Old English Sheepdogs. Young to middle age females are more predisposed.
If your dog is showing symptoms of IMHA he should be seen by a veterinarian as soon as possible. Immune-mediated hemolytic anemia can be fatal if not treated.
Immune-mediated hemolytic anemia in dogs is a disease where the immune system attacks and breaks down the body’s red blood cells. The immune system normally defends the body from bacteria and virus infections. The disease causes abnormal antibodies to fend off the body’s own red blood cells. The red blood cells are destroyed faster than the bone marrow is manufacturing them.
Symptoms of Immune-Mediated Hemolytic Anemia (IMHA) in Dogs
- Lethargic
- Tachycardia - Fast heart beat
- Polyuria - Frequent urination
- Darker colored urine
- Tarry/dark stool
- Polydipsia - Increased thirst
- Pallor - Paleness seen on the gums, underside of the ears and the inner eyelids
- Jaundice (icterus) - Yellow pigmentation in the sclera (white part of the eye), along the gum line, pinnae (inner ear flap), genitals and on the abdomen
- Weakness
- Decreased ability to exercise
- Dyspnea - Shortness of breath
- Lack of appetite
- Fainting
- Nose bleeds
- Seizures
- Vomiting
- Collapse
Types
- Primary IMHA (idiopathic) - No underlying reason for the disease (this is the most common type of IMHA; 60-75% of patients with immune-mediated hemolytic have primary IMHA)
- Secondary IMHA - Is triggered by a condition or activated by an agent
Causes of Immune-Mediated Hemolytic Anemia (IMHA) in Dogs
Primary IMHA
- The body’s own immune system is at fault.
- Genetic implications
Secondary IMHA
IMHA can be triggered by:
- Recent vaccination
- Medications
- Tick exposure
- Zinc or copper intoxication ( ingesting pennies, batteries, zinc oxide cream)
- Cancer
- Toxins
- Stress of estrus
- Infections caused by Babesia, Ehrlichia, and Leishmania
Diagnosis of Immune-Mediated Hemolytic Anemia (IMHA) in Dogs
If your pet has been seen by another veterinarian it is recommended that you bring his medical records with you. Even if it was just a wellness check, the records can provide a baseline. The veterinarian will go over the patient’s medical history. Let the veterinarian know if your pet is on any current medications, has had recent vaccinations or has been exposed to any toxins.
The veterinarian will perform a physical examination on the patient. The examination may include taking the patient’s weight, temperature, pulse and blood pressure. The veterinarian may listen to the dog’s heart and lungs using a stethoscope. He may also check the patient’s eyes, ears and gums.
After the your companion’s physical examination, the veterinarian may recommend diagnostic testing. The blood work that may be recommended include a complete blood count, serum chemistry profile, blood smear, reticulocyte count, slide agglutination test, and a direct Coombs test.
- Complete blood count - Can determine the patient’s platelet, red and white cell count and can also help determine if there is a bacterial infection; patients with IMHA will have a low red cell count, higher white cell count, low platelets and elevated liver enzymes
- Serum chemistry test - Evaluates organ functions and the electrolyte balance
- Blood smear - Can find abnormalities in blood cells; 89% of patients with IMHA have spherocytes, which are red blood cells shaped like spheres, instead of the normal disk shape
- Reticulocyte count test - Measures how fast red blood cells are made and released from the bone marrow
- Slide agglutination test - Can help determine if the red blood cells are being affected by an immune disease
- Coombs test - Can visualize/ detect the immune system’s antibodies on the surface of red blood cells
Other diagnostic tests that may help find the underlying reason for secondary IMHA are x-rays, ultrasounds, zinc toxicity test, urinalysis and polymerase chain reaction (PCR) assay.
Treatment of Immune-Mediated Hemolytic Anemia (IMHA) in Dogs
If the patient’s red blood cell count is severely low, the veterinarian may suggest hospitalization. The patient can then receive 24/7 intensive care. Once hospitalized your dog may receive a blood transfusion, supplemented oxygen treatment and medications. Initial medications commonly used for treating IMHA are prednisone (corticosteroid) and doxycycline (antibiotic).
Other medications that may be prescribed include azathioprine, cyclosporine, mycophenolate mofetil and Leflunomide. These medications must be closely monitored because they can have adverse side effects (gastrointestinal tract irritation, nausea, susceptible to infections, lethargy). Patients that do not respond to the immunosuppressive medications may need to have a splenectomy.
Patients with secondary IMHA will also need to be treated for the underlying condition. The veterinarian will discuss with you what the best treatment plan is for the diagnosed condition.
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Recovery of Immune-Mediated Hemolytic Anemia (IMHA) in Dogs
There have been recent studies that show that some dogs may be slowly weaned off the medication after three months of treatment. There is the possibility of relapse; 12 -24% of patients must be placed back on the medications. Dogs that respond to the treatment plan have a fair prognosis. Frequent follow up visits will be necessary to monitor the patient’s progress and to check for complications from the prescribed medications.
Immune-Mediated Hemolytic Anemia (IMHA) Questions and Advice from Veterinary Professionals
Collie Shepherd Mix
Candy Martin
13 Years
6 found this helpful
6 found this helpful
My pet has the following symptoms:
Aiha
I recently had to put my dog down because of this condition. They tried to treat her and nothing they did helped they claim that her liver functions were affected by this disease. My main question is first off how does a healthy dog just Falls ill one day to the other of this condition and what can I do to prevent this from happening again with my other dog that just recently adopted
July 20, 2018
6 Recommendations
Immune-mediated haemolytic anaemia is where the body’s immune system attacks normal healthy red blood cells; the specific cause is not fully understood with no concrete correlation between vaccination, infections, medications or other factors although there are some cases which do suggest some link in some cases. There is no specific way to prevent this condition, but it is an uncommon condition and statistically unlikely to occur in another pet of yours. Regards Dr Callum Turner DVM
http://veterinarymedicine.dvm360.com/imha-diagnosing-and-treating-complex-disease
July 21, 2018
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Shih Tzu
Koda
5 Years
7 found this helpful
7 found this helpful
My pet has the following symptoms:
Pale Mucous Membranes
My 5 year old Male Shih Tzu recently passed away from IMHA. I am considering getting another Shih Tzu from the same breeding
pair. Is there any chance IMHA is hereditary? Could my new puppy get IMHA as well? And is there any evidence vaccines cause IMHA?
April 3, 2018
7 Recommendations
Some breeds (Cocker Spaniels) are more prone to immune mediated haemolytic anaemia than others, although there is no evidence to support an hereditary link. Also, there have been claims that vaccinations may cause immune mediated haemolytic anaemia due to stimulation of the immune system and a 1996 study found a temporal relationship but further studies didn’t find that vaccination increased the risk of immune mediated haemolytic anaemia. Regards Dr Callum Turner DVM
http://veterinarycalendar.dvm360.com/adverse-vaccination-events-separating-fact-fiction-proceedings
April 3, 2018
I recently had to put my dog down because of this condition. They tried to treat her and nothing they did helped they claim that her liver functions were affected by this disease. My main question is first off how does a healthy dog just Falls ill one day to the other of this condition and what can I do to prevent this from happening again with my other dog that just recently adopted
July 20, 2018
Mary A.
Was this question and answer helpful?
Shih Tzu
Snickers
5 Years
1 found this helpful
1 found this helpful
My pet has the following symptoms:
Lethargy
Pale Mucous Membranes
Loss Of Appetite
Thirst
Heavy Breathing
Lack Of Coordination
I recently had to make the hard decision to lay to rest my Shih Tzu. He was 5 years old. He had mild back problems starting in Oct of 2019, which was treated with Carprofen and was well up until April of 2020. His back pain returned and he was treated with Carprofen. After 4 days his symptoms didn’t improve and he was placed on prednisone and gabapentin for pain. He was weak and his appetite diminished and I was told he’d need an mri after x rays showed him having mild degeneration of the disc in his mid/lower back. I took him to the ER after he had an episode of collapsing and he was given Robaxan for his pain, and referred to a neurologist for an mri. I couldn’t afford the mri so his primary vet prescribed buprenorphine. His gums were pale and after bloodwork was done he was found at 8%PCV and referred to an internist. The internist diagnoses him with hemolytic anemia possibly due to immune mediated, or medication induced. He said a transfusion might be needed however the risks were high since his body was rejecting and not making its own RBC. He continued with prednisone, vitamin B12 injection, and melatonin to help with regeneration. Within 3 days we were back at the ER. Although his PCV went up to 9% his chances were low and he went into cardiac arrest. I had to make the hardest decision ever to lay him to rest. Knowing I did everything I could since he was 8 weeks old to keep him healthy- sometimes I regret not doing more. I hope this experience can bring someone reading this comfort to know that some things are out of our control. Snickers may have left this earth but his paw print is forever engraved in my heart.
