"Pet dogs are a powerful spontaneous model for human cancers. Dogs develop the same cancers that humans do, with striking similarities at the clinical, histopathological, and genomic level. We have developed a new Twist canine exome capture with a focus on comparative cancer applications, and are applying it to develop blood biopsy in the canine model. Blood biopsy is a non-invasive method for measuring and sequencing cell-free tumor DNA in the bloodstream, with exciting potential applications for longitudinal patient monitoring and diagnosis. By refining blood biopsy in dogs, we hope to inform its application in both veterinary and human medicine.