Amegakaryocytic thrombocytopenia in a dog: Diagnostic challenges and therapeutic considerations

A 7-year-old spayed female beagle was presented to its primary veterinary practice with vomiting, lethargy, and signs of hemorrhage. Investigations revealed severe thrombocytopenia and regenerative anemia. Following referral and further investigations, an initial diagnosis of primary immune thrombocytopenia was reached. Treatment with vincristine and prednisolone was initiated; however, the platelet count failed to increase, prompting the addition of cyclosporine. The platelet count temporarily improved but never normalized and subsequently declined again. A bone marrow biopsy confirmed a diagnosis of amegakaryocytic thrombocytopenia. Adjustments in treatment, including initiation of azathioprine, led to an increase in the platelet count. However, following an acute onset of respiratory distress, the owner perceived the dog's quality of life to be poor, leading to a decision for euthanasia. This case highlights the diagnostic challenges of distinguishing amegakaryocytic thrombocytopenia from primary immune thrombocytopenia and the complexities of managing this rarely reported condition in animals. Key clinical message: This report describes the clinical presentation, diagnostic investigation, and treatment of a case of amegakaryocytic thrombocytopenia. It highlights the diagnostic challenges presented to confirm this pathology in our patients. Early consideration of bone marrow examination is warranted in the diagnostic evaluation and management of refractory thrombocytopenia, given that the prognosis for and therapeutic implications of amegakaryocytic thrombocytopenia differ significantly from those related to other etiologies.