Exploring the Epidemiology of Melanocytic Tumors in Canine and Feline Populations: A Comprehensive Analysis of Diagnostic Records from a Single Pathology Institution in Italy.

Simple Summary: Melanocytic tumors (MTs) are more prevalent in dogs than in cats. In dogs, they are the most frequent malignancy of the oral cavity, whereas in cats, ocular melanomas predominate. This study provides epidemiologic data (2005–2024) on MTs for both dogs and cats. Totals of 21128 canine and 4808 feline tumors were analyzed by the Veterinary Pathology Service of the Department of Veterinary Medicine (University of Perugia). Among these, 845 canine MTs (329 melanocytomas; 512 melanomas) were diagnosed, 485 from the skin, 193 from the oral mucosa, and 104 from the mucocutaneous junction. Older dogs were more likely to develop melanomas than melanocytomas (p < 0.001). In contrast, among feline tumors, only 60 were melanocytic (6 melanocytomas, 53 melanomas). Of these, 29 were cutaneous, 18 were ocular, and 9 were oral. In dogs, melanomas were more common in mucocutaneous locations than in cutaneous locations (p < 0.05); moreover, they were more common in the oral cavity compared to all other sites (p < 0.001). In cats, ocular melanomas were more common than cutaneous ones (p < 0.05). This study provides the prevalence of MTs in dogs and cats, supporting distinct epidemiological patterns of MTs, and confirming the significance of species-specific differences in the tumor prevalence, localization, and age distribution. MTs are prevalent in dogs, representing the most frequent oral malignancy, compared to cats, in which ocular melanomas predominate. This study investigates the canine and feline MT epidemiology (2005–2024) of cases submitted to the Veterinary Pathology Service (University of Perugia). Among the canine neoplasms, 845 (4%) were melanocytic: 329 (39%) melanocytomas; 512 (61%) melanomas. Of these, 485 (57%) were cutaneous (4% of canine cutaneous neoplasms), 193 (23%) were oral (50% of oral canine neoplasms), and 104 (12%) were mucocutaneous. The average age of affected dogs was 10 years. Older dogs were more likely to have melanomas compared to melanocytomas (p < 0.001). There were 60 (1%) feline MTs: 6 (10%) melanocytomas; 53 (88%) melanomas. Of these, 29 (48%) were cutaneous (1% of feline cutaneous tumors), 18 (30%) were ocular, and 9 (15%) were oral (22% of feline oral tumors). The average age of affected cats was 11 years. In dogs, mucocutaneous melanomas were more common compared to cutaneous ones (p < 0.05); oral melanomas were more common compared to all other sites (p < 0.001). In cats, ocular melanomas were more common compared to cutaneous ones (p < 0.05). Our study provides the MT prevalence in a selected canine and feline population, revealing MT epidemiological patterns, highlighting species-specific differences in the tumor prevalence, localization, and age distribution. [ABSTRACT FROM AUTHOR]