Often we cannot figure out what caused thrombocytopenia. Tick borne diseases are the most common, cancer is also a possibility, but with the age of your dog the most likely cause is immune-mediated thrombocytopenia (ITP).

At 59,000 platelets spontaneous bleeding is highly unlikely. This is not a problem, it is a good thing that your dog is not bleeding. Most of the time, I don't see bleeding in my patients. One of my last patients with ITP was feeling a little cruddy but responded beautifully to just pred and doxy (he tested negative for tick borne diseases though). One patient was a complete surprise; we were just testing liver/kidney values after starting her on chronic NSAIDs. She is also doing well, but had a little relapse.

I haven't had to use Atopica (cyclosporin) on any of my patients yet- they have all done well on pred alone for immunosuppression.

The time on pred is extremely variable and depends on how your dog responds. I usually have my patients get a CBC every 2 weeks and taper as soon as the platelet count comes back to normal. So far, all of my patients have had normal platelet counts at the 2 week check, and I start decreasing the pred at that point. My current patient's platelet count dropped after I dropped the pred, so we had to go back up- she's due for a recheck this week. She didn't go down to where she was originally. She started at 4,000 platelets and went up to 225k at the 2 week check but then down to 115k at the 4 weeks check. So basically I have to start her over. She should do OK though.

Don't make ANY changes to your dog's medications without specific instructions from your vet. Decreasing or stopping pred too suddenly can cause SERIOUS problems such as an Addisonian crisis which is life-threatening. Cyclosporin takes a few weeks to start working, so pred is used concurrently until it kicks in.

Some dogs take months before completely off pred. That's OK. Be patient.

Am I reading things correctly that it took several months to figure out the platelets were low? Why wasn't a CBC done when your dog first got sick? A CBC and chemistry profile are among the first diagnostics done on any animal when sick.

Good luck with Sponge.