AbstractBlood samples from 3 unrelated Akita dogs with a common history of persistent macrothrombocytopenia in the absence of clinical bleeding were sent to the Auburn University College of Veterinary Medicine (AUCVM) Clinical Pathology Laboratory for evaluation. Due to low platelet counts, one Akita dog had been treated with corticosteroids for presumed immune‐mediated platelet destruction, and one Akita dog was treated with doxycycline for one month for presumed infection by a tick‐borne agent. In spite of treatment, platelet counts remained low in both dogs. Given the absence of abnormal bleeding in all 3 dogs and lack of response to treatment in 2, congenital macrothrombocytopenia was suspected. Interestingly, platelets from all 3 dogs exhibited a consistent elongated platelet morphology. There were no morphologic abnormalities observed in other cell lines. While there have been anecdotal reports of a possible inherited macrothrombocytopenia in Akita dogs, scientific studies have not been done to verify these reports. This manuscript represents the first case report describing what is likely a congenital macrothrombocytopenia in Akita dogs based on persistently low platelet counts in the absence of clinical signs, and characterized by a unique platelet morphology.