IMHA

About Canine Immune-Mediated Hemolytic Anemia (IMHA)

Mediated-Hemolytic-Anemia (Previously referred to as AIHA- Autoimmune Hemolytic Anemia)

Overview

The red blood cells serve the crucial function of carrying oxygen to the cells in the body and picking up carbon dioxide. Anemia is a condition that arises when the number of red blood cells falls below normal values, or the red blood cells function improperly. There are many diseases and conditions that can cause anemia in dogs. A low red blood cell count can be the result of blood loss, the destruction of the red blood cells, or an inadequate production of new red blood cells.

When your dog has IMHA, it means his immune system destroys its own red blood cells. Your dog’s body still produces red blood cells in the bone marrow to replace the destroyed cells, but once they are released into circulation, the immune system mistakenly recognizes them as something foreign, like a virus or infection, and destroys them. This condition is also referred to as autoimmune hemolytic anemia (AIHA).

Causes

There are two forms of IMHA: primary (or idiopathic), and secondary IMHA.
With primary IMHA, your dog's immune system mistakenly produces antibodies that attack its own red blood cells. This is the most common cause of anemia in dogs.

With secondary IMHA, the surface of your dog’s red blood cells is modified by an underlying disease process, drug, or toxin. Your dog's immune system identifies the modified red blood cells as something foreign and destroys them. When too many red blood cells are destroyed and not replaced quickly enough by bone marrow, the patient becomes anemic. Secondary IMHA can be triggered by a variety of conditions, such as:

Cancer
Infection
Blood parasites
Drug reactions
Snake bites
Exposure to certain chemicals and toxins
Bee stings or other allergic reactions


Symptoms

Symptoms may include:

Pale gums
Acting tired, weak, or listless
Shallow or rapid breathing
Faster than normal pulse
Lack of appetite
Weight loss
Black/Tarry stools
Eating dirt

These symptoms can vary from dog to dog and depend upon the underlying cause of IMHA. In some situations (mild or early IMHA), your dog may present no signs at all!

Diagnosis

When a dog is anemic, it is important to identify the underlying cause. Your veterinarian may recommend particular tests, depending on your pet’s symptoms and history. These tests may include:

A complete blood count to identify if your dog is anemic, and, if so, to determine whether or not his body is responding to:

The anemia by producing new red blood cells

A reticulocyte count to identify if your dog’s body is responding to the anemia by making new red blood cells

A blood film to look for parasites and blood cell characteristics

Chemistry tests to evaluate kidney, liver, and pancreatic function, as well as sugar levels

Electrolyte tests to ensure your dog isn’t dehydrated or suffering from an electrolyte imbalance

Urine tests to screen for urinary tract infection and other disease, and to evaluate the ability of the kidneys to concentrate urine

Fecal analysis to evaluate for intestinal parasites

Patient-side screening for vector-borne disease

Specialized tests that can help identify underlying infectious disease (e.g., various titers, PCR testing)
Treatment

Treatment of IMHA depends on the severity of the condition. Your veterinarian will determine whether your dog needs intensive care or can be treated as an outpatient. Treatment often includes a variety of drugs and close monitoring of your pet’s vital signs and laboratory values. With secondary IMHA, treatment of the underlying cause is critical for recovery. Your veterinarian will recommend blood and other diagnostic tests including radiographs and ultrasound to try to determine if your pet’s IMHA is primary or secondary.

Your veterinarian may also recommend you see a specialist to help outline the best treatment plan possible, particularly if your dog requires 24-hour monitoring or specialty testing. The prognosis of a dog diagnosed with IMHA is dependent upon the underlying cause, the severity of disease, and the stage at which the disease is diagnosed.

Your veterinarian can best help you understand your pet’s prognosis based on his specific diagnosis, overall health, and history.

If you have any questions or concerns, you should always visit or call your veterinarian – they are your best resource to ensure the health and well-being of your pets.

In Bonnie's case this disease was diagnosed late, when the most severe symptoms were obvious. This was due to the fact that Bonnie had Cushings and SARDS and so one of the main symptoms of IMHA being listlessness and lack of energy were also symptoms of the Cushings and SARDS, so it wasn't obvious that there was something else lurking undiagnosed.

She had her 3 monthly ACTH test for Cushings 2 weeks before she passed away, which is quite an involved blood test, and she came through that with flying colours, showing she was coping well, as we thought, on her Cushings medication, Vetoryl, and the vet recommended she stayed on the same dose. It wasn't until 2 weeks after on Monday 7th September I noticed she was slightly off balance and not quite herself. Having a Cushings dog you tend to be very observant with them, so any slight change in behaviour and I tended to take her to the vet for a checkup.

If she hadn't had Cushings or SARDS then I would have spotted this horrid disease much much sooner and perhaps managed to save her life. But as the vet said, it can come on very quickly and its a very aggressive disease and once it gets hold, there's nothing much you can do to stop it. The vets tried everything in those 24hrs to save Bonnie, but the disease was too advanced and too dominant, and her immune system was so weak it was almost destroyed by the disease. As soon as she was making new red blood cells they were being destroyed immediately by the disease. So even a blood transfusion wouldn't have helped her, it would just have fed the disease.

I have no proof, but I am convinced that the Cushings medication had a lot to do with her getting IMHA. And I went through a period of terrible regret, in not taking one of her vet's advice and not putting her on treatment, but 2 other vets recommended the treatment and said the prognosis on Vetoryl for Cushings dogs is good. So I went with their advice and ignored the previous vet. But as the vet who last treated her on those fateful last 2 days said, Vetoryl may have contributed to it, or it could have been anything, such as vaccination, an insect bite, they just don't know.

All I know is I did everything in my power to save her, but it was not to be. And in the end I wanted her put to sleep as soon as possible as it broke my heart to see her suffering so. This has been the only time in my entire life that I have wanted to lose a furbaby and for euthanasia to be carried out immediately if not sooner. It wasn't a hard decision, but what was hard was losing my special loving adorable gentle sweet little girl who fought all her life with illness and tried so hard to stay with me. She was only 7yrs old. She didn't even get the 3yrs the vet said she 'might' have on Vetoryl, she only got 6mths. But she'll live forever in my broken heart until I join her in heaven.

I hope and pray that if you're reading this, you never have to experience this with your Cushings dog, but that it helps you to watch for any symptom or anything any change in behaviour and act on it immediately. Don't wait until the morning, or if its at the weekend, postpone the vet until Monday. Get help straight away.