The enormous biological complexity of human cancer has stimulated the development of more appropriate experimental models that could naturally and spontaneously resemble the physiopathologic aspects of cancer biology. Companion animals possess many desired characteristics that bridge the gap between in vitro and in vivo studies, and these characteristics have proven to be important in understanding many complex molecular aspects of human cancer. Spontaneous tumors in dogs share a wide variety of epidemiologic, biological, and clinical features with human cancer, which makes this animal model both attractive and underutilized in oncology research. 

It is worth examining canine tumors as a valuable model for studying numerous aspects of human cancer, as well as the potential use of this animal model in developing new cancer diagnostics and treatments. For example, canine lymphoma, osteosarcoma, or canine mammary tumors can serve as models to study cancers in humans.