A 6 year old castrated male Afghan hound presented to the Cornell University Hospital for Animals with a chief complaint of Bruising, swelling of the right hind limb, and hematuria. A presumptive diagnosis of Immune-Mediated Thrombocytopenia (ITP) was made based upon clinical signs and laboratory investigation, and an appropriate diagnostic protocol was designed to rule out secondary causes of thrombocytopenia. Therapy with immunosuppressive doses of corticosteroids, doxycycline, and adjunctive immunosuppressive drugs was initiated. Sequential monitoring of platelet numbers confirmed resolution of clinical and laboratory signs of thrombocytopenia. This paper discusses ITP with special emphasis on the history, presentation, diagnosis, and treatment of this specific case