What Is Hemolytic Anemia In Dogs

Anemia is a sign of another disease process or condition rather than being a distinct illness. Anemia is a term used in medicine to describe a lack of haemoglobin (Hb), red blood cells (RBCs), or both.

In the bone marrow, red blood cells are created and subsequently released into the bloodstream. Red blood cells are taken from the bloodstream and recycled to create new red blood cells as they deteriorate or grow old. The amount of red blood cells in circulation may be decreased if there is a decline in bone marrow production, lysis (or destruction), or if there is an increase in the loss of red blood cells from the circulation, as is the case with haemorrhage (bleeding).

The body’s cells and tissues receive oxygen through haemoglobin, therefore an anaemic dog will exhibit symptoms of low oxygen levels.

What is autoimmune hemolytic anemia?

In contrast to hemolysis, which derives its name from the Greek words hemo, which means blood, and lysis, which means to rip open, autoimmunity refers to an immune response against the body’s own tissues. A condition known as autoimmune hemolytic anaemia (AIHA) affects the immune system and causes the body to attack and eat its own red blood cells. Red blood cells are still produced in the bone marrow of dogs with AIHA, but once they are circulated, they live less time than usual.

The immune system disorder known as “autoimmune hemolytic anaemia (AIHA)” causes the body to attack and destroy its own red blood cells.

What causes autoimmune hemolytic anemia?

With primary AIHA, the immune system of the dog malfunctions and produces antibodies that are misdirected against its own red blood cells. About three-quarters of instances of AIHA in dogs are thought to be primary.

In secondary AIHA, a toxin or underlying disease process changes the surface of the red blood cells. The changed red blood cells are subsequently identified by the dog’s immune system as ‘foreign’ intruders that must be eliminated. Cancer, infection with Ehrlichia or Leptospira, blood parasites like Babesia (see handout “Babesiosis in Dogs”), pharmacological reactions, snakebites (see handout “Snakebite Envenomization”), chemicals, poisons, or bee stings can all cause secondary AIHA. Neoplasia or malignancy seems to be the most typical cause of secondary AIHA in canines. AIHA may be brought on by stressful situations if there are underlying secondary reasons already present.

In secondary AIHA, a toxin or underlying disease process changes the surface of the red blood cells.

Once targeted, the red blood cells either undergo intravascular hemolysis, which results in their destruction within the blood arteries, or extravascular hemolysis, which results in their destruction as they pass through the liver or spleen. Hemoglobin will be released in both scenarios, and the liver’s workload will increase as it tries to break down the excess amounts.

What are the symptoms of AIHA?

In contrast to the usual pink to red hue of their gums, dogs with AIHA typically have significant anaemia and will have very pale gums. Because there aren’t enough red blood cells to transport oxygen to the tissues, dogs with anaemia will be listless and will exhaust more quickly. Due to insufficient brain oxygen levels, the dog can pass out or seem confused. Heart rate and respiration (breathing) rate will rise as a result of the tissues receiving less oxygen.

The skin, gums, and other mucous membranes become yellow or jaundiced when bilirubin levels are too high.

Excessive levels of bilirubin, a byproduct of red blood cell hemolysis, accumulate in the body as the condition worsens. This extra bilirubin sometimes leaks into the urine, turning it black. The skin, gums, and other mucous membranes become yellow or jaundiced when bilirubin levels are too high. The dog can throw up or have a weak appetite.

How is AIHA diagnosed?

A blood test called a complete blood count is used to identify anaemia (CBC). Several different values are measured by the CBC in a sample of whole blood. Red blood cells will be counted, their packed cell volume (PCV) will be quantified to determine the percentage of red blood cells in the sample, and the cells will be studied under a microscope to assess their size and shape to screen for anaemia.

Red blood cell counts and percentages will be low in those with AIHA, and the size and form of the cells will be aberrant. There will frequently be signs of “autoagglutination,” or abnormal clumping of red blood cells, along with symptoms of AIHA.

Your veterinarian will also advise additional diagnostic procedures if AIHA is detected in order to distinguish between primary and secondary disease. A reticulocyte test, which counts the quantity of reticulocytes (immature red blood cells) in the bloodstream, an antibody test like the Coombs test, and serologic blood tests to identify specific diseases are some examples of testing (e.g., babesiosis, leptospirosis, ehrlichiosis, or heartworm).

What other tests are important with this disease?

To determine your dog’s general health and to look for any underlying causes of secondary AIHA, your veterinarian may advise additional tests. A biochemical profile, a urinalysis, chest and abdominal X-rays, and an abdominal ultrasound examination are frequently advised testing. Other tests might also be suggested, depending on your pet’s particular results.

While the urinalysis will give a baseline assessment of kidney function and show whether there is evidence of an infection in the urinary system, the biochemical profile will assess organ function and electrolyte levels. While abdominal X-rays or ultrasounds can detect or rule out the existence of cancer within the belly, chest X-rays help detect or rule out the presence of cancer in the lungs.

How is AIHA treated?

A blood transfusion will be required if your dog’s anaemia is so serious that it poses a life-threatening risk. Blood samples will be collected beforehand for cross-matching (like blood typing). The main goal of a blood transfusion is to stabilise the dog so that additional treatments may start working and the underlying reason of the anaemia can be identified.

“A blood transfusion will be required if your dog’s anaemia is so severe that it poses a life-threatening risk.”

If AIHA is secondary, the underlying cause will be treated with various antibiotics, heartworm medication, or toxin antidotes, if any are available.

Immunosuppressive therapy will be utilised if no underlying cause can be found, or if primary or idiopathic AIHA is established to be the condition. The dog may respond quickly to therapy with immunosuppressive dosages of corticosteroids in some cases of idiopathic AIHA (usually prednisone). In some situations, a cocktail of immunosuppressive drugs, including azathioprine or cyclosporine, may be required to try and control the illness.

Based on the findings of the diagnostic tests, your veterinarian will specify a treatment plan unique to your dog’s requirements. Your veterinarian could suggest referring difficult cases to an internal medicine specialist.

What is the prognosis for AIHA?

The exact diagnosis and the dog’s overall health at the time of diagnosis both affect the prognosis for dogs with AIHA. The patient’s condition can frequently be controlled with the right medication therapies. Your veterinarian would advise tapering off the immunosuppressive drugs over a period of many months to lessen any negative effects related to therapy after the patient’s condition improves and the anaemia cures or stabilises. You must keep a watchful eye on your dog as dosage is reduced or stopped because relapses are frequent with this illness.

Does a dog who has hemolytic anaemia recover?

Both dogs and cats can develop the dangerous and potentially fatal illness known as immune-mediated hemolytic anaemia (IMHA). In essence, this indicates that your pet’s immune system, which usually defends against viruses and intruders, is suddenly battling its own red blood cells. This leads to the destruction of red blood cells, which results in anaemia and inflammation (damage) all over your pet’s body.

Since it has been identified in small animals for more than 80 years, IMHA is a disease for which there is currently no perfect cure. Nevertheless, your pet has a far higher chance of survival now than they did in the past thanks to the availability of numerous newer medications and treatments. Up to 75% of dogs with IMHA can make a full recovery and resume their usual lives with appropriate treatment.

What results in a dog’s hemolytic anaemia?

RBC loss causes hemolytic anaemia. The most frequent cause in dogs is immune-mediated destruction, however infections, tumours, and other factors can also be to blame. Immunosuppressive medications are used to treat immune-mediated hemolytic anaemia. The underlying cause is addressed in order to treat other types.

Regenerative hemolytic anemias are caused by the lysis of RBCs in the intra- or extravascular area. Hemoglobinemia and hemoglobinuria are caused by extravascular hemolysis, but not by intravascular hemolysis. Icterus may develop from either kind of hemolysis. In dogs, immune-mediated hemolysis accounts for 60%–75% of cases of hemolytic anaemia, while other factors such as toxins, RBC damage, infections, neoplasia, and RBC membrane abnormalities can also result in hemolysis.

What signs might a dog have of hemolytic anaemia?

Nothing is scarier to a pet owner than an illness that might take our animals from us without cause or prior notice. However, a disorder called immune-mediated hemolytic anaemia (IMHA) is able to do just that.

Even though you’ve probably never heard of it, it’s crucial to educate yourself so that, in the event that you ever have a pet who is affected by IMHA, you can act quickly and effectively.

What is Immune-Mediated Hemolytic Anemia in Dogs?

The disease’s name speaks for itself. Anemia develops in pets with IMHA because the immune system starts to kill (hemolyze) the animal’s own red blood cells.

In IMHA, the pet’s antibodies start attacking the bloodstream’s red blood cells. These cells develop an antibody coating that makes them susceptible to being destroyed. These red blood cells are then lysed or “popped” by the body, taking them out of circulation.

A pet who has too few red blood cells is effectively oxygen-deprived because red blood cells are crucial for carrying oxygen throughout the body. In addition, the liver and spleen, which typically assist in the removal of used red blood cells, are overworked.

What are the Symptoms of Immune-Mediated Hemolytic Anemia?

Because IMHA patients have low red blood cell counts, pet owners frequently observe:

  • Weakness
  • sluggishness or depression
  • a diminished appetite
  • dark orange to brown urine
  • White to yellow skin and gums
  • Jaundice (yellow discoloration, especially of the whites of the eyes)
  • sometimes fever

Any time a pet displays these signs, it is crucial to have them examined straight away. Particularly IMHA can develop and advance quite quickly. All of these, while not specific to IMHA, may indicate a major issue.

What Causes Immune-Mediated Hemolytic Anemia in Dogs?

The immune system can be triggered by anything, including IMHA. This might be a disease, a bug bite, or even a shot. But in around 60–75% of cases, the reason for the immunological response is still a mystery.

Additionally, several breeds appear to be predisposed to IMHA. These consist of:

  • Spaniels, Cocker
  • Dublin Setters
  • Ancient English Sheep Dogs

How is Immune-Mediated Hemolytic Anemia Treated?

Patients who acquire IMHA require aggressive therapy. There are three objectives for treatment:

Getting rid of the trigger

Although there is no known cause for the majority of IMHA instances, if one exists, it must be eliminated. In order to check for any issues that require treatment, pets with IMHA frequently require thorough diagnostic testing.

halting the immunological response

Obviously, the key to success is halting the aberrant immunological reaction. Prednisone and other corticosteroids are frequently used to achieve this. Additional immunosuppressive medications are occasionally required.

Giving comforting care

The immunological response cannot be immediately stopped, and the body needs time to heal. Patients frequently require one or more blood transfusions throughout treatment to aid in their recovery. Numerous IMHA patients are in serious condition and need to be admitted to the hospital.

Immune-mediated hemolytic anaemia is a dangerous illness that necessitates prompt medical attention. Some people don’t survive even with superb care. It is crucial for pet owners to be aware of the symptoms of IMHA in order to treat their animals at the earliest possible stage of the illness. Catching issues early on in their development is essential for success, as it is with so many conditions we observe.

How long does an autoimmune hemolytic anaemia in dogs last?

Immune Mediated Haemolytic Anaemia is referred to as IMHA. Because it’s a bit of a mouthful, it’s frequently referred to by its less awkward abbreviation. It’s not as complicated as it may seem, and here we’ll try to clear up any confusion.

What is IMHA?

IMHA is a member of the class of conditions known as autoimmune disorders. These occur as a result of the immune system mistakenly classifying the body’s own cells as foreign. Then, these cells are attacked and eliminated. Different cells are the targets of each autoimmune illness. Red blood cells are targeted and destroyed with IMHA, which results in decreased levels (anaemia). Similar platelet cell loss is also experienced by two thirds of dogs with IMHA. Immune-mediated thrombocytopenia, or thrombocytopenia, causes excessive bleeding because platelets are necessary for clot formation (ITP). We refer to the combination of the two disorders as Evans syndrome.

What causes this?

An antigen is a protein found on the surface of body cells. This protein is used by the immune system to recognise its own cells. In IMHA, red blood cell antigens are mistakenly identified as foreign, which prompts the immune system to produce an antibody. The cell swells and ruptures as a result of the antibody’s attachment to the antigen. Increased cell clumping (agglutination) increases the risk of irregular coagulation.

Idiopathic refers to a sickness whose cause is uncertain. We refer to it as idiopathic IMHA, or primary IMHA, because this is the case in about 70% of IMHA cases.

Secondary IMHA is the underlying cause of the remaining 30% of cases. Secondary IMHA can result from certain illnesses, which are primarily transferred by parasites like ticks. Most don’t happen often in the UK but should be taken into account, particularly if your pet has travelled abroad. IMHA has been linked to a number of drugs, including certain antibiotics and analgesics. Additionally, some cancers can result in IMHA. There is currently no evidence to support the theory that a recent vaccine could cause the condition. The advantages of vaccination far outweigh the hazards in the majority of dogs because it protects against serious, life-threatening infections.

Cocker spaniels and Old English sheepdogs appear to have a genetic propensity, but any breed is susceptible.

What are the symptoms?

The ensuing anaemia is largely to blame for the symptoms. Weakness, tiredness, and a lack of appetite are a few possible symptoms. Since red blood cells transmit oxygen throughout the body, a dog lacking in oxygen will frequently have a rapid heartbeat and rapid breathing. The gums are typically pale, but occasionally they may have a yellow tint because bilirubin, a substance with a yellow tint that is produced when red blood cells rupture, is broken down.

Any organ that has suffered damage due to a lack of oxygen might show a variety of symptoms, and because red blood cells have a propensity to clump together, clots can form anywhere.

How is IMHA diagnosed?

First, we determine whether anaemia is present. We must further characterise the type of anaemia present because there are numerous causes of anaemia. The majority of dogs with IMHA have regenerative anaemia, in which the body is encouraged to manufacture additional red blood cells in order to make up for ones that have been lost. Non-regenerative anaemia is conceivable in rare circumstances where the bone marrow is impacted.

Next, we rule out any additional regenerative anaemia causes as well as less common causes of hemolysis including heavy metal toxicity or onion poisoning, and we determine whether your pet has recently received any drugs or immunizations. We might perform additional testing to find malignancies or infectious reasons.

We frequently seek for certain cell types known as spherocytes, which are small, rounded red blood cells frequently associated with IMHA, when we analyse blood under a microscope. Reticulocytes, which are immature red blood cells, may be more numerous, indicating that the anaemia is regenerative. In addition to other specialised tests like the Coombs test, which checks for antibodies on the red blood cells, we frequently send samples to a lab for confirmation. In a test called saline agglutination, red blood cells are combined with saline to see if they cluster together. Although rapid and reasonably priced, it can be challenging to interpret.

Can this condition be treated?

Prednisolone, a corticosteroid that suppresses the immune system, is the primary treatment for many autoimmune diseases. In the beginning, high doses can be required in order to gradually reduce and eventually quit using the prescription. In severe cases or if prednisolone has severe adverse effects or is ineffective, a second immune suppressing medication can be used. Azathioprine is the most often used drug since it is affordable, but it takes some time to act and needs special treatment. Although it is expensive, has an unpredictably wide dosing range, and causes side effects, cyclosporine is approved for usage in dogs.

As a final resort, the spleen may be removed to aid in preventing red cell oxidation (splenectomy). By this point, pets are severely ill, making the procedure dangerous. Sadly, many owners would be forced to think about euthanasia as a substitute.

Aspirin may be prescribed if we believe there is a danger of excessive clotting in order to reduce it.

Although a blood transfusion may appear clear, new cells could be swiftly eliminated, making the symptoms worse. A transfusion may be advised since the danger of injury from the lack of oxygen in severe anaemia may be greater.

Regular blood tests would be used to assess how well the treatment was working. We can hopefully reduce any medicine gradually once a response is observed while continuing to sample for any parameter worsening. We might also want to keep an eye out for any prescription side effects.

What is the outlook?

With IMHA, the prognosis varies, with a death rate ranging from 30% to 70% within 1-2 months after diagnosis. The prognosis could be worse if patients experience IPT simultaneously or if the bone marrow is compromised. Some animals require lifetime treatment since the illness can recur.