The purpose of this illustrative case series is to explore the use of canine liquid biopsy for noninvasive cancer detection and monitoring in surgical case management. Liquid biopsy using next-generation sequencing (NGS) of cell-free DNA (cfDNA) for noninvasive canine cancer detection was recently validated in a study of over 1,000 dogs for use as a screening tool, and as an aid-in-diagnosis. This technology has other applications in the post-diagnosis setting, which are currently in use for management of cancer in human patients. This study reviews three illustrative case examples of common, surgically managed tumor types in which NGS-based liquid biopsy is applied in dogs. These cases demonstrate the ability of liquid biopsy to assess residual disease and longitudinally monitor patients following surgery to potentially identify molecular recurrence of disease prior to the reemergence of clinical signs. This proof-of-concept case series provides data from a very small number of cases. Studies are currently underway in a larger cohort to evaluate the use of a clinically validated canine liquid biopsy test for these applications, and other post diagnosis uses. The data generated by such studies may offer benefit to the surgical community as another tool for post-surgical disease monitoring in dogs.
