An approximately 9-year-old female intact Labrador presented to her primary care veterinarian with a complaint of increased amount of vaginal discharge, lethargy, and inappetence. She was diagnosed with an open pyometra accompanied by a severe thrombocytopenia and referred to Cornell University Hospital for Animals (CUHA) for treatment. Two weeks prior to her presentation the patient was taken in to her primary veterinarian to be spayed, however bloody vaginal discharge was noted and she was presumed to be in heat, thus ovariohysterectomy was not performed at that time. Initial physical examination at CUHA was unremarkable except for a small amount of bloody vaginal discharge, lethargy and inappetence. The patient's condensed problem list up to that point included; open pyometra and a thrombocytopenia. Differentials for a severe thrombocytopenia were discussed including consumption due to disseminated intravascular coagulation, sequestration by the spleen or other organs, decreased production by the bone marrow due to neoplastic invasion, infection, or other myeloproliferative disorders, or destruction via immune mediated processes. Ultimately the most likely diagnosis given the severe thrombocytopenia (3 thou/uL, reference interval: 186-545) was an immune mediated thrombocytopenia (ITP), likely secondary due to the concurrent pyometra. Due to the surgical risk of pursuing an ovariohysterectomy for removal of the inciting cause; medical management was enacted to treat the pyometra while waiting for immunosuppressive therapy (Prednisolone 30 mg every 12 hours) to improve the number of circulating platelets. An acceptable platelet count was achieved, and the patient was discharged home for a short while before returning for an ovariohysterectomy. Upon re-presentation, the patient had developed diabetes mellitus secondary to high progesterone levels, however with proper insulin therapy in addition to an ovariohysterectomy, her blood glucose levels normalized and since then she has been weaned off insulin therapy. The patient is currently receiving immunosuppressive therapy for her ITP and is doing well at home.