Background: The canine osteosarcoma is characterized by being an aggressive bone tumor that affects mainly large dogs,
middle-aged and male, accounting for 80-85% of bone tumors and 5-6% of all tumors. The risk of developing this tumor is, on
average, 125 times greater in dogs weighing over 36 kg than in dogs weighing less than 9 kg. This cancer develops more
frequently in the appendicular skeleton (75%), preferably the bones of the forelimbs, where approximately 60% of body
weight are sustained. The canine osteosarcoma is very similar to human, in which the metaphyseal region of long bones is the
most affected, causing lameness and swelling of the affected limb. The diagnosis is made from epidemiological data, history
of the animal, X-rays and laboratory tests such as cytology fine-needle aspiration (FNAC) and measurement of the enzyme
alkaline phosphatase (ALP). The staging of the disease becomes a major method for the treatment, whereas primary bone
tumors are highly complex and end up interfering with the animal organism in whole. The objective of this study is to report
a clinical study of 12 dogs with osteosarcoma, showing the procedures performed from diagnosis to treatment.
Material, Methods and Results: Dogs were assisted at the Clinic of Small Animals VUH - UFSM and after the clinical
examination were referred to the Department of Radiology. After the radiographic study, blood samples for biochemical and
material for cytological analysis of the tumor were collected. After the confirmation of the neoplasm, the physician who
prescribed the treatment, depending on the case, the accession to it was left to the owner. In this study, we observed the
development of osteosarcoma in dogs from two to 14 years old. Furthermore, in 10 animals (83.3%) the tumor was located in
one of the members and nine of these (75%) affected forelimbs. Still, eight dogs (66.7%) were males. The animals weighed on
average, 30 kg and five were crossbreeds. Eight dogs (66.7%) had an elevation in enzyme ALP. In this study, five dogs (41%)
received no treatment, four (33.3%) were killed and three (25.7%) had the treatment as prescribed by the clinician. Three of the
dogs treated survived for a few weeks and two of those who received appropriate treatment survived more than a year.
Discussion: The clinical and epidemiological findings of this study corroborate the literature, making them increasingly used
in the auxiliary tests cited. For a proper diagnosis it is necessary for the veterinary practitioner to know which tests to determine
use. Approximately 98% of the patients have micrometastases at diagnosis, however, only 5% of dogs with osteosarcoma have
radiographic evidence of pulmonary metastasis. These will only cause clinical signs in advanced stages, leading the majority
of dogs to euthanasia. Moreover, the appearance of bone thinning and explosion in the limb are strong indications of
osteosarcoma. The FNAC is one of the main tests for diagnosing neoplastic, because the laboratory technician can visualize
the tumor cells in proliferation and other features visible only under a microscope. The enzyme alkaline phosphatase is of great
value in the diagnosis and prognosis of this tumor and may demonstrate metastases when elevated. Epidemiological data
along with auxiliary tests make the diagnosis of this neoplasm safer, which assists the owner in the decision for the treatment
of the affected animals. As there is still little understanding of the anticancer treatment by the owners, treatment schedules may
not be implemented, which prolongs the disease and causes more suffering to the dogs.
