Immune-Mediated Thrombocytopenia: A Frustrating Disease

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’s History

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.

Coco’s Treatment

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.

Coco’s Progress

Within a few days of treatment, Coco’s petechiae (bruising) faded, and no new bruising appeared.

Most important, 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.

As I mentioned, Coco’s platelet count remains in the lower normal range. This is good news.

But she is showing some problematic side effects from the steroids, and this is what I want to share with you in case your pet is prescribed steroids for a serious problem.

What Is a Steroid?

A sidebar here about the terms “steroid” and “corticosteroid”: Many clients hear the word “steroid” and are confused. They might be thinking about anabolic steroids, not corticosteroids.

Anabolic steroids are those testosterone-like drugs that are misused by athletes and body builders. When your veterinarian talks about using a “steroid,” she is almost always talking about a corticosteroid.

Corticosteroids are used to control many diseases, ranging from allergies to immune-mediated diseases to certain cancers. Cortisol helps control many metabolic and physiologic processes, including stress response, inflammation, immune response, protein metabolism and electrolyte levels, to name a few.

The most common side effects of corticosteroids are increased thirst and appetite. The no-brainer follows — more urination.

The medical shorthand we use for this syndrome is PU/PD/PP (polyuria/polydipsia/polyphagia) (increased urination/increased thirst/increased appetite).

There is also a kind of steroid crazy where the dog is just nuts! Eating, drinking, urinating and running around like a maniac.

Coco Attempts Suicide on Steroids

Already crazy and still struggling with potty training, Coco on steroids is faster than a speeding bullet. Able to leap tall cabinets in a single bound. More powerful than any locomotive.

Super-steroid dog Coco has tried to eat anything not nailed down — and has found many things we thought were nailed down: Ancient Chinese takeout condiments. Human gummy vitamins. Newly purchased coffee.

I wait in line at the fabulous Porto Rico Coffee in NYC and cherish my purchase. But Coco, on steroids, broke into my organic Sumatra. The coffee is now embedded into a carpet that will never recuperate because she chose to bury it indoors, not eat it.

I was finishing up Saturday morning appointments and left Coco at the house for the last 30 minutes. I arrived home to find she had scaled a counter and put herself into a toxicosis state by eating an ancient bag of semi-sweet chocolate chips in a high, closed cabinet.

At times like this, I wish I had a nanny-cam. How the (bleep) did she get into that cabinet?

Saving My Own Dog

My dog had ingested a lethal dose of chocolate. She was shaking, had tremors and was on her way to a seizure. Time to go into ICU mode with my own dog.

Classic treatment for chocolate toxicosis is immediate emesis (making the dog vomit). Success! The vomit included the pound of semi-sweet chocolate chips and an undigested fortune cookie with the wrapper. Yay!

I gave her activated charcoal to absorb more toxin and monitored her 24/7 until she was out of danger. Soon enough, she was doing just fine. But what is the lesson learned?

If Your Dog Must Take Steroids

Keep an open conversation going on with your vet. Your dog may exhibit many side effects. It is impossible to predict how she’ll be affected.

The dosage and the type of steroid is always negotiable. If the side effects are severe, your vet may try to change the dosage, the particular drug or change drugs completely.

This Vet Always Learns From Her Own Pets

Coco is exhibiting intense steroid-induced hunger. House-training, which was going well, is a bigger challenge right now.

These are big reminders for me to be even more sympathetic to others experiencing these problems when their pet is on lifesaving steroids.

Vets must listen. A client might say something like, “Poco’s driving me crazy with her appetite on prednisone.” Or, “She’s peeing so much I can’t take it.” A vet might say, “Yes, it’s a common problem.” But what we need to say is, “How bad is it? What’s going on? Give me specifics.”

Coco could have died if I had not come right home after work. The house is pretty pet-proof, but not if she’s on a steroid hunger mission.

Keep that open dialogue with your vet and remember this: No question or concern is dumb or stupid. It’s what we are here for. And you might just save your pet’s life.

This pet health content was written by a veterinarian, Dr. Debora Lichtenberg, VMD. It was reviewed for accuracy by Dr. Pippa Elliott, BVMS, MRCVS, and was last updated Oct. 13, 2018.