Neoplasmas ósseos e osteopatia hipertrófica em cães

Abstract

This doctoral thesis involved the study of three groups of neoplasms that affect bones of dogs (primary bone neoplasms, bone metastases, and multicentric neoplasms with bone involvement) and a bone lesion, often paraneoplastic, known as hypertrophic osteopathy. The study of primary bone neoplasms covered important pathological and epidemiological aspects for the diagnosis of this group of tumors, with emphasis on osteosarcomas. It was retrospectively performed, covering a period of 22 years. Reports of biopsy and necropsy cases of dogs received at the Laboratório de Patologia Veterinária, Universidade Federal de Santa Maria (LPVUFSM) were analyzed. Out of the 90 primary bone neoplasms diagnosed in this period, 89 were malignant. Osteosarcoma was the most prevalent (86.7%) neoplasm. Regarding osteosarcomas, most cases occurred in large and giant breed dogs, between six and 10 years of age. The neoplasms predominantly involved the appendicular skeleton and were 3.5 times more prevalent in the forelimbs than in the hindlimbs. The predominant histologic subtype was the osteoblastic. For the study of neoplasms that comprise the second and third groups, i.e., neoplasms with bone metastases or with bone involvement by multicentric neoplasms, a prospective study was conducted over a period of three years. The skeleton of 110 dogs, with 118 malignant neoplasms of different origins received in the necropsy service of the LPV-UFSM were examined for bone lesions. Twenty-one cases of bone metastases or bone involvement by multicentric neoplasms (19.1%) were detected. In general, the bone lesions affected more female dogs. However, when mammary gland neoplasms were not considered, the distribution of cases according to the sex was very similar. The mean age was 9-years-old and dogs of different breeds were affected. The mammary gland was the primary site of most bone metastases, followed by neoplasms of the musculoskeletal and respiratory systems. Most metastases were observed grossly and occurred in multiple bones. However, in 23% of the cases metastases could only be observed microscopically. Vertebrae and humerus were the mosdt frequently affected bones. Simultaneously, seven cases of hypertrophic osteopathy, diagnosed in a period of 11 years at the LPV-UFSM, were retrospectively and prospectively studied. Affected dogs had clinical signs of bone involvement and lesions mainly in the long bones of the limbs. The lesions consisted of periosteal bone neoformation, detected on radiographs, bone inspection during necropsy, and with great level of detail, in macerated bone specimens. The bone proliferation was partially circumferential and occurred mainly in the diaphysis of long bones. It consisted of bone trabeculae of irregular size and thickness, which were arranged perpendicularly to the original cortical bone. In all cases, the lesions of hypertrophic osteopathy were associated with lung neoplasms (primary or metastatic). In two of the seven cases, the lung metastases were of primary bone sarcomas and, in one case, there was a primary lung osteosarcoma (extra-skeletic).