• age
• animal cancer registry
• pet
• veterinary oncology

Cancer is a leading cause of mortality in companion animals, yet the lack of standardized screening protocols poses significant challenges in early detection and intervention. Animal Cancer Registries (ACRs) significantly enhance our understanding of oncology, providing insights into epidemiologic and clinical trends, and fostering comparative research. This study describes the development of a pathology-based ACR of the University of Pisa in coordination with national and international networks and provides a comprehensive analysis of canine and feline oncological data, focusing on the age at diagnosis, tumor distribution, and risk factors associated with malignancy, as well as breed-specific predispositions. Over 20,000 histologically confirmed cases of canine and 5,000 cases of feline neoplasia (2008–2023) from Pisa and Lazio ACRs were retrospectively analyzed, all coded using the Vet-ICD-O-canine- 1 system. In dogs, the median age at diagnosis for benign and malignant tumors was 9 and 10 years, respectively. Large body size, brachycephalic and dolichocephalic skull shapes, and female sex accelerated malignancy diagnosis. For cats, the median age for malignant tumors was 11 years, with male and non-purebred cats diagnosed earlier. The malignancy analysis of canine and feline cancer data revealed that malignancy risk increased with age and was higher in cats, females, and in breeds such as the Dogo Argentino, Rottweiler, and Boxer. In contrast, purebred cats and canine breeds like the West Highland White Terrier, Cocker Spaniel, and Poodle had a lower malignancy risk. Significant changes in tumor occurrence during the years were observed. In addition, new potential tumor predispositions were identified in breeds such as Italian Cane Corso, Maremma Sheepdog, Jack Russell Terrier, Doberman Pinscher, Pug, Springer Spaniel, and Maltese. These findings underscore the value of multicenter collaborations and standardization in animal cancer registration in shaping more accurate, evidence-based screening guidelines tailored to specific breeds, ages, and tumor types in companion animal oncology.