Mammary carcinomas are common malignant tumors encompassing the main diagnostic mammary gland tumor cause in female dogs and cats. Few reports in wild animals are, however, available. In this context, this study aimed to characterize the clinical and histological aspects of a mammary tubular carcinoma case in a guinea pig (Cavia porcellus). A four-year-old non-spayed female guinea pig was seen at a veterinary clinic in the municipality of Natal, Rio Grande do Norte, Brazil. Upon clinical examination, the animal was active, with a normal body condition, weighing 660 grams, hydrated, and presenting normal-colored mucous membranes. Increased left breast volume was observed, about 3.5 cm in diameter, non-adherent and with an ulcerated surface located medially to the mammary papilla, about 1.8 cm in diameter. The observed clinical findings indicated a presumptive neoplastic lesion diagnosis. A unilateral mastectomy was performed (left breast) and breast tissue fragments were histologically evaluated, confirming the tubular mammary carcinoma diagnosis. The surgical procedure and post-surgical treatment recommended in this report were proven efficient. Knowledge of diseases that affect non-conventional pets, such as the tubular mammary carcinoma reported herein, is paramount in improving the quality of life of these animals.

Osteosarcomas are noteworthy as one of the main malignant bone tumors in dogs and cats, comprising an important cause of limb amputation in these species. Literature reports for felines are, however, scarce. Therefore, the aim of the present study was to characterize the clinical and histopathological findings of a chondroblastic osteosarcoma case in a female cat. The chondroblastic osteosarcoma diagnosis was based on radiographic, cytological, histopathological and immune-histochemical findings. Clinical, radiographic, and cytological findings suggested a presumptive osteosarcoma diagnosis, while histopathological and immune-histochemical findings confirmed a chondroblastic osteosarcoma diagnosis.