He had an episode of ITP (immune mediated thrombocytopenia) that caused his platelets to be destroyed by his own body and thus caused bleeding and a need for blood transfusion. Caution is advised with any future surgeries and anesthesia (although technically if stable he should be fine during procedure, it's post op I would be more worried about triggering another episode). I would also advise caution with vaccines- performing titers for distemper and parvo, using a 3 year rabies vaccine with a benadryl pre-treatment and no other vaccines (flu, kennel cough, lyme , etc). I would even consider not vaccinating him at all and not boarding him (having a petsitter if needed if going away and not able to take him). Signs of recurrence would be unexplained bruising, weakness, petechiae on gums (small pinprick purple or red bruises), pale mucous membranes (eyes, lips, gums, mouth), and possibly lack of appetite.
 
He is not currently taking any medication and was weaned down slowly to ensure he would be ok. 
 
I let Virginia know he was ready for adoption (today) and she mentioned she was rather attached (first time she had said anything to me). Had that conversation only an hour or so ago. So a heads up she may want to adopt him (and she has been excellent with his care and now familiar with his condition). Let me know if you would like to talk further,