Immune Mediated Disease in Dogs


No pet owner ever wants to see their furry friend sick. That’s why it is critical to give them the proper nutrients they need for a strong and healthy immune system. Minor colds usually won’t need veterinary attention, however, if your dog has an immune mediated disease, symptoms and treatments will likely be much more serious. An immune mediated disease is a condition that occurs when the immune system abnormally attacks the central nervous system, leading to serious health complications.

The two most common canine immune mediated diseases result in anemia. To begin, let’s take a closer look at immune mediated hemolytic anemia (IMHA). In its early stages, IMHA is treatable, however in an acute stage, it can be life-threating.

Immune mediated thrombocytopenia (ITP) is another disease that causes a failure in the immune system. While many assume that these diseases are quite similar, they require different treatment strategies and should be dealt with on a case-by-case basis.

Two forms of IMHA exist: primary IMHA and secondary IMHA. These diseases have different symptoms and causes, but are both anemic diseases that require specialized treatment. While symptoms of anemia like lethargy or lack of appetite can be a sign of IMHA, some dogs may not have any symptoms at all during the earlier stages of the disease.

ITP symptoms are mainly related to spontaneous bruising or failure to clot blood, which can result in excessive bleeding. If you are concerned that your dog may be suffering from an Immune Mediated Disease, read below to learn more about symptoms and treatment. Your dog will likely need veterinary attention to ensure proper treatment and a safe recovery.

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Types of IMHA in Dogs

A healthy immune system can normally defend itself from bacterial, fungal, parasitic, and viral infections that attack your dog’s body. The immune system consists of antibodies, white blood cells, and other proteins and tissues that rid the body of unwanted substances. These antibodies are key components of the immune system, which are programmed to destroy antigens – the foreign substances that cause sickness.

Cells are typically marked and registered as “self” and “non-self” cells, which help these antibodies determine which cells should be kept or rejected. This is how dogs, as well as humans, fight off colds and illnesses after no more than a few days at a time.

However, when the dog’s immune system mistakenly recognizes its own red blood cells as foreign substances, these antibodies destroy healthy red blood cells that are needed to carry oxygen throughout the body. This indicates an immune system failure, which leads to an essential “short circuit” of the immune system, and causes tissue failure.

Red blood cells are produced in the bone marrow, however if the body attacks these cells, the bone marrow will not be able to keep up with the high demand of red blood cells. Anemia will result from this deficiency and the body’s immune system will be compromised.

In the case of primary IMHA, the red blood cell count falls far below the normal count. There are no proven causes for primary IMHA, however there are many theories that are tied to this illness. Some of these theories stem from additives found in dog food, pollutants from the environment, cancer, and vaccines that could have altered the immune system’s functionality.

Other theories link the disease to genetic predisposition or hormonal influences, which are more natural processes, but specialists and researchers still cannot trace most cases of primary IMHA back to its roots.

In cases of secondary IMHA, anemia occurs when the red blood cells do not function properly. This happens when an underlying disease, drug, or toxin modifies the surfaces of a dog’s red blood cells. Similar to primary IMHA, the red blood cells are then destroyed and cannot be replaced quickly enough by the bone marrow. This can sometimes stem from a cancer or infection, blood parasites, chemicals and toxins, or even allergic reactions.

primary IMHAsecondary IMHA

Typical IMHA Symptoms

Symptoms can vary from dog to dog. Irish Setters, Poodles, English Springer Spaniels, American Cocker Spaniels, Dachshunds, Miniature Schnauzers, and Doberman Pinschers are said to be the most commonly affected breeds, especially within the ages of one to thirteen years old. Female dogs seem to be slightly more predisposed to this illness than their male counterparts.

Normal symptoms of anemia can include lethargy, poor appetite, rapid or shallow breathing, jaundice, weight loss, and a rapid pulse or heart rate. Because anemia is just one symptom of IMHA, other signs of IMHA can include melena (black stools due to hemorrhage, or partly digested blood, in the gastrointestinal tract), petechia (red or purple spots on the body due to minor hemorrhages), or ecchymoses (patches or bruises that may appear as skin discoloration).

IMHA symptoms dogs at a higher risk for IMHA

Acquiring Proper IMHA Diagnosis

When taking your dog to a veterinarian, several tests should be taken in order to create a specific treatment plan for your pet.

A complete blood count and reticulocyte count will determine whether your dog is anemic or not, and will also show if red blood cells are being produced in response to the anemia. If the results are abnormal, a bone marrow sample might be needed to investigate the production of red blood cells further.

Depending on your veterinarian, they may want to do further testing to fully understand the severity of the illness. These tests may include chemistry tests for kidney, liver, and pancreatic function, electrolyte balance tests, and urine/fecal tests to screen for infections, diseases, parasites, or overall internal organ functionality.

In addition to the biochemical profile and urinalysis tests, x-ray images might be helpful to screen vital organs including the thorax, abdomen, heart, lungs, liver, and kidneys.

Echocardiography and ultrasounds are also used to see if there are any abnormalities in the body’s high-functioning areas. These tests, of course, should be discussed with your veterinarian before determining whether it is necessary for treatment. Keeping a checklist of symptoms that your dog has faced may be helpful when deciding which tests to run.