Hemangiosarcoma is an aggressive cancer that develops from blood vessels. When it occurs in a dog’s heart, it is difficult to safely collect samples for testing, which makes confirming the diagnosis challenging. This highlights the need for a new, minimally invasive diagnostic tool. Any dog breed can develop hemangiosarcoma; however, it is more commonly seen in large breeds such as German shepherd dogs, Golden retrievers, and Labrador retrievers. This disease occurs more frequently in older dogs. With this project, we aim to develop a new diagnostic approach that can be used by general practice and emergency veterinarians, especially those without immediate access to specialists or advanced imaging equipment, such as CT scan. If successful, this research could lead to a less invasive, more accessible, and more accurate diagnostic tool for veterinarians, including those without access to advanced diagnostic equipment. This may ultimately improve clinical decision-making and patient outcomes.