Abstract
Mammary tumors are among the most common neoplasms in dogs and cats, and malignant forms are clinically important in both species. Surgery remains the main treatment approach and may be combined with other treatment modalities, but advanced cases are often associated with recurrence and limited responsiveness to conventional therapies. Phytochemicals and plant extracts have received attention as potential adjuvant agents that can modulate pathways associated with oncogenesis and treatment resistance. Natural products are often accessible and relatively inexpensive, and their perception as well-tolerated agents may increase owner acceptance. Some plant extracts and phytochemicals, including Euphorbia royleana extract , celastrol, and homoharringtonine have shown potent preclinical activity in canine mammary tumor cell lines and xenograft models, but data for feline mammary tumors are still limited. However, their safety and efficacy depend on multiple factors such as the compound, dose, formulation, and species. Further studies are required for clinical translation, as species-specific pharmacokinetics significantly affect efficacy and safety. This review summarizes current knowledge on plant extracts and phytochemicals in canine and feline mammary tumors, focusing on their preclinical evidence, limitations, and future translational challenges in veterinary oncology.