Immune-Mediated Thrombocytopenia

Today’s blog comes from a big word with a rather simple meaning when you break it down; and from my little paralyzed Dachshund who decided it would be an awesome idea to try this. Immune-mediated (immune system started it), thrombocytopenia (decrease in platelets; our cells that clot our blood).

In our blood we have three different types of main cells, white blood cell (WBC), red blood cells (RBC) and platelet (Plt). They all have specific jobs to do to keep our pets healthy.

When there is damage to a part of the body platelets form together, forming a clot to stop bleeding. A platelet lifespan is 8-12 days and in a healthy state, there is anywhere from 200,000 -500,000 platelets circulating to protect from bleeding. The bare minimum to prevent spontaneous bleeding is 20,000-50,000. The spleen stores about 1/3 of the circulating platelets in case they are needed for immediate use.  Small bruising is called petechiae and large bruising is called ecchymosis.

So why would the body go after its own? There are many reasons this can happen, ITP can be primary, secondary or idiopathic (unknown reason) like many other diseases process. However, the science behind it is that the body is insulted, and antibodies coat the platelets with markers (like little flags) that they are foreign invaders. The immune system, thus the spleen since it is what cleans up platelets, goes into over-drive to clean up these foreign invaders. The body is overwhelmed and cannot keep up with this destruction, if the bone marrow has time/or is able to make a response it will send out mega-platelets, that were not ready for circulation yet. However, these platelets will only have a lifespan for 1-2 days, unlike the 8–12-day lifespan of normal platelets.

What can be done for our pets with this disease? First, it all depends on how long our pet’s platelets are where the first steps will be – however it is all typically the same. Try to determine the initial insult to the immune system. For my current old man (by the way I’ve had 3 dogs will immune-mediated disease – so any questions feel free to ask) I was taking him in for a suspect urinary tract infection and ran full lab work – SURPRISE – ITP. I rechecked the numbers the following day and sure enough, he had 80,000 platelets. No other symptoms yet, no bruising, no lethargy, no decreased appetite – just increased thirst and urination for the UTI (mind you I express him). So, reminder of how important yearly and semi-yearly bloodwork for our senior pet’s is. Ok then, so what can be done – find out what may be going on, so that includes lab work; CBC, chemistry, UA, tick-borne testing; from there is depends how far you want to take your testing to find a cause, please discuss with your veterinarian.

Treatment options will always typically start with immune-suppressive therapy, we must tell the immune system to STOP marking the platelets for destruction. Prednisone is typically #1 go to. One or multiple secondary medications will also typically be added on like Azathioprine, Cyclosporine, cyclophosphamide, mycophenolate. If platelets are low enough or not responding to conventional therapy chemotherapy with Vincristine can be given to help stimulate a sudden burst of platelet production.

So, for now, managing ITP – last platelet count for old man Freckles was 200,000! Yippy! Back in the normal zone, he refused to co-operate and donate a sample last week, so next week we shall see. I will try to take pictures from the microscope of his actual platelets. If I am successful, they will be posted on my Instagram account, which is linked on the website. Happy Thursday everyone, go make happy platelets!