low platelet count

My 7 year old male boxer has an extemely low platelet count.  We adopted him from a rescue group in Dec 2006.  He had a mass cell tumor on his side and I had it removed in July 2007.  The tests revealed it was a grade II.  At the time of his surgery, his platelet count was 27.  He has been fine since his surgery. (Active-loves to play.)  I took him for his annual checkup in Jan 2008 and blood work was done to check his platelet count.  It was a 12.  So he was prescribed prednisone 20 mg  2 tablets every 12 hours to get it in his system. I am aware of the side effects of drinking alot of water & gaining weight, but he could not handle the dose. He had to go to the bathroom every 2 hours, starting using the bathroom in the house (Never done before).  I backed off the dosage to 1 every 12 hours and called the vet.  He now has no energy,  won't eat, won't play, has lost weight and acts as if his body is in pain.  He will stand up as long as possible and when he is worn out he will finally lay down.  When he was rechecked at the vet, he had blood in his urine and his platelet count was a 4!  A tick serology was done, but results won't be received for about 5 days. (He was tested in July 2007 and this was negative.)  He is now on doxycycline 100mg 2 in am, 2 at pm.  Still not active and acts stiff and it is hard for him to get up and walk.  He was fine until we started the prednisone. Any advice would be greatly appreciated.  

[Jaybay]

I think your questions are better answered by the vet, Dr. Aleda Cheng, who volunteers here at Med Help.  To access that forum, look on the right side of this page under Related Expert Forums and click on Pet Health.

I'm just a layperson, but this sounds serious - like all-out cancer or even kidney failure.  You're right about the prednisone too.  Just like people, some dogs can't tolerate it at all.  He probably is in pain, so ask your vet about something for that.  Tramadol works well and is inexpensive.