Metronomic chemotherapy in small animal practice: An update

Metronomic chemotherapy can be considered a new chemotherapy modality involving continuous administration of low doses of cytostatic agents which targets endothelial cells. Endothelial cells are vital for the development of new blood vessels and are essential for tumour growth. Furthermore, these cells are genetically stable, divide at a high rate and do not acquire resistance to cytotoxic drugs as tumour cells. Therefore, they are sensitive to low doses of cytostatics. Because of the importance of metronomic chemotherapy in veterinary medicine, this review provides an update of the status of metronomic chemotherapy in small animal practice. In dogs with cancer, metronomic chemotherapy can be considered a good treatment option and a first-line therapy. Further studies evaluating the levels of regulatory T cells Tregs and tumour microvessel density are needed to better understand the role of this therapeutic modality in different canine tumours.