What is an immune mediated disease?
First of all, an Immune Mediated disease and an Auto-Immune disease are the same thing and the terms can used interchangeably. These diseases are ones in which the body is attacking its own cells. Instead of the immune system only attacking foreign invaders to keep the body healthy, somehow a malfunction occurred and the body labeled its own cells as being bad and is killing them.
We don't fully know what causes the body to attack itself, but some of the theories being tested currently include:
Immune mediated diseases can be extremely frustrating to determine if they are a primary or secondary immune reaction, but it is crucial for prognosis (long term outcome) of the pet. Unfortunately, diagnosing primary immune disease is a diagnosis of rule outs. What this means is the veterinarian must test for, and rule out, all the other causes that can set off the immune system. We'll cover this is in a different post.
Treatment for any immune mediated disease is to suppress the immune system. Essentially the immune system is on hyper-alert and over-reacting, so we use drugs to dampen and suppress the immune system. The treatments vary slightly for the different auto-immune diseases and specifics will be discussed for those individual diseases.
Immune Mediated Blood Disorders
The hematologic (blood) diseases that fall into this category all have two things in common:
The diseases in this group are called:
IMHA typically presents with a patient that is extremely anemic and pale. They can be lethargic and have loss of appetite.
IMTP patients present with bruising, either small pin point spots (pettechia) or large bruising. They can have spontaneous bleeding such as nose bleeds (epistaxis), bloody urine (hematuria) or stool (hematochezia), bloody vomit (hematemesis), or other random bleeding. These patients may also be anemic, pale, lethargic, or not eating because they may have had excessive bleeding from not being able to clot appropriately.
Evans Syndrome patients present with symptoms from both IMHA and IMTP since it is both diseases rolled into one.
IMN patients are sometimes difficult to identify, but it is common for them to get multiple infections easily and that are difficult to get rid of.
Immune Mediated Polyarthritis (IMPA)
IMPA involves the immune system attacking the joint tissue in pets. This results in pain, stiffness, and swollen joints.
Panniculitis is when the body attacks the fatty tissue beneath the skin. This can manifest in random lumps and bumps that can change in size. This is diagnosed by biopsy.
There are more immune mediated diseases, so let us know if there's another one you'd like us to discuss. We'll continue the discussion of the diseases mentioned in this article individually. The links will go live as soon as they are ready.
I hope this basic overview of immune mediated diseases helps. Keep an eye out for more on the subjects soon! Leave a comment and let us know what you think.
Yvonne Brandenburg, RVT, VTS (SAIM) is a Registered Veterinary Technician practicing in California and obtained her Veterinary Technician Specialty in Small Animal Internal Medicine in 2016. She is the founder of InternalMedicineForPetParents.com. For more about Yvonne visit her author page here.
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