A review of spontaneous bone metastases in domestic and laboratory animals

• Bone metastases cause significant morbidity and death in cancer patients. • Animals with naturally occurring cancers are unique models for cancer research • This review covers the natural history of bone metastases in non-human species. Bone metastases cause significant morbidity and ultimately death in some human cancer patients. Although experimental animal models of skeletal metastases have been invaluable for investigating the molecular mechanisms of cancer progression and growth in bones, few of these models recapitulate the heterogeneous nature of bone metastases observed in humans. Animals with naturally occurring cancers have been proposed as ideal and unique models for human cancer research. From this, understanding the incidence, histologic features, clinical presentation, and response to therapy of spontaneous bone metastases in animals with different cancers will help with animal model selection and translational experiments on bone metastasis. This review provides an overview of the natural history of spontaneous bone metastases that occur in animals with spontaneous cancer. The review focuses on companion animals (dogs and cats) and includes rodents and other animal species. The similarities and differences compared to human bone metastases are highlighted, permitting a valuable resource for future skeletal metastasis modeling and therapeutic discovery.