Immune-mediated thrombocytopenia (IMT). Idiopathic immune-mediated thrombocytopenia.
A mouthful of a disease. It’s also called immune-mediated thrombocytopenia purpura (ITP).
As frustrating as the crazy names of this disease are, the disease is even more frustrating to treat. IMT is more common in dogs — middle-aged female dogs, poodles and Cocker Spaniels are over-represented, in fact — but cats can acquire it too.
What Is IMT?
IMT refers to immune-mediated destruction of platelets.
Before I lose you, it’s this simple: Platelets help in the clotting of blood for our pets as well as for ourselves. If you didn’t have platelets, a small bruise could be a disaster. Platelets help to seal up a blood vessel and stop the bleeding and the bruising.
In immune-mediated destruction of platelets, a body (whether dog, cat or human) attacks its own platelets. The body views this fantastic little platelet as an enemy and destroys it. This destruction must be stopped in order to survive. We need what are called immunosuppressive levels of drugs to counteract the destruction. The first line of defense: corticosteroids, nasty but lifesaving drugs in many instances.
Signs and Symptoms
The most common symptom of a low platelet count (thrombocytopenia) is bruising. There may also be blood in the urine and feces or nosebleeds, but the hallmark sign is small bruising for no reason. These are called petechiae.
Here’s Why It’s Frustrating
- It’s idiopathic, meaning we don’t know the cause — perhaps an infection or a neoplastic process or even a toxin — but again, we just don’t know.
- It has an unknown outcome.
- It is usually treated with high doses of corticosteroids (prednisone, for example), which have many side effects.
- If the treatment begins to work and the disease goes into remission, we have to be careful about stopping treatment too soon.
- The pet can stop treatment, but the disease could return after remission.
- Diagnosing, monitoring the disease and additional drug therapy, if indicated, can get very expensive.
“But My Dog Looks Fine”
Imagine your veterinarian giving you the bad news that your healthy-looking dog, usually a fairly young or middle-aged dog, has a bad disease. The vet tells you:
- We don’t know what caused it.
- We don’t know if your dog will respond to treatment.
- We have to use dangerous drugs at high doses to treat the disease.
- The treatment might or might not work.
- The disease might return after remission, and that it might cost you a lot of money — but we don’t know how much.
You might think your vet doesn’t have a clue what she’s doing, and your head is spinning from this confusing and depressing information. That’s how most clients react.
My Puppy Has IMT
About 2 weeks ago, I diagnosed my own 18-month-old pup with IMT. This really sucks.
Coco is a fairly new rescue for me. We adopted her last summer from a family who had to rehome her. She is a Dixie dog who looks like a tiny, dark wolf running in the snow with golden eyes.
She loves to turn over on her back, spread-eagled, and one morning, I bent down to rub her tiny belly and noticed pretty significant bruising (petechiae). I then looked at her gums (mucus membranes) — sure enough, her entire mouth was full of petechiae.
Time for an emergency vet visit. Fortunately, that just meant taking her to work with me across the driveway.
Her automated platelet count was 0. She actually had about 15,000 platelets, but if this didn’t turn around fast, she was headed for the ICU and transfusions. In the saddest scenario, she would not recover.
Because I’ve treated this disease so many times with outcomes ranging from complete failure (the dog dies) to a quick and lasting remission, my mind was immediately spinning. I was thinking the worst but hoping for the best.
It really stinks when you have to give your own dog a serious diagnosis. I’ve treated dogs with IMT who did not recover. And because the treatment can be harsh, I remember the angry clients who got so frustrated by treating IMT that they took it out on me. It’s understandable.
Within a few days of treatment, Coco’s petechiae (bruising) faded, and no new bruising appeared. Most importantly, her platelet count returned to normal within the week. She is responding perfectly to treatment but still exhibiting some of the side effects of the prednisone.
Keep the faith, Coco-Loco-Coco-Puff! In my next article, we learn more results.
This pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. It was last reviewed March 16, 2016.
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Editor’s Note: This is Part 1 of 2 articles from Dr. Deb on immune-mediated thrombocytopenia. Continue to Part 2 here.