This retrospective study was completed by Dr. Celic Berenice Montoya, pathology resident at the Departamento de Patología, Facultad de Veterinaria of the prestigious UNAM in Mexico, during her rotation at Noah's Path in 2017. In this study, published recently by Revista de Clínica Veterinaria de Pequeños Animales of AVEPA, 6 cases of chondrosarcoma are described in guinea pigs, with predilection for flat bones and, in 3 patients with metastases. Chondrosarcomas are diagnosed in guinea pigs more frequently than in other exotic mammals, in which they are very rare.