| Abstrakt: |
Background: Chinchillas are small, long-lived hystricomorph rodents closely related to guinea pigs, porcupines and agoutis. Used extensively in scientific research and fur production, its use as a pet has grown exponentially in the last decade, increasing their presence in veterinary clinics and hospitals. The most common health conditions for chinchillas kept as pets are a result of husbandry or dietary deficiencies, and they rarely develop neoplasia. Although rare, neoplasias do occur in these animals and should be included as differential diagnosis. This report describes the occurrence of mammary adenocarcinoma in a companion chinchilla with several metastatic foci in lungs, liver and kidneys. Case: A 6-year-old female chinchilla (Chinchilla laniger) was presented with progressive hyporexia, apathy and a volume increase in the right axillary region. Since the owner noted purulent secretion in the ulcerated mass, he began treatment, without veterinarian consent, using topic rifampicin, 0.5 mL dipyrone sodium oral and 1.5 mL of enrofloxacin. All of which were used orally, once a day, for five days. On presentation at the veterinary hospital, the animal was poorly responsive, mildly dehydrated and had moderate body condition. Physical examination revealed pale mucous membranes, body temperature of 36.4°C and an increased volume, soft upon palpation, near inguinal area. The mass in the right axillary region was adhered, soft and ulcerated. A fine-needle aspiration was performed and the animal was sent home with instructions to perform forced feeding until the citology results were obtained, which were inconclusive. At the owner's request, no other diagnostic tests were performed. Six days after initial examination the animal lost 5% of its body weight as anorexy, lethargy and locomotion difficulties progressed, at which point the owner requested euthanasia. The animal was sent for postmortem examination. Discussion: At the time of the necropsy the animal presented great abdominal distention. Gross inspection revealed a slightly firm nodule in the right axillary region measuring 5x5x3 cm, with an area of ulceration of 1 cm in diameter. Another slightly firm nodule of 1 cm in diameter, dark red when cut, was observed in the right inguinal region. Histopathological examination of the mammary gland revealed a delimited and unencapsulated neoplastic proliferation, organized in multiple lobules separated by moderate to severe fibrovascular stroma. Neoplastic cells were arranged in acinar and tubular structures, showing moderate anisokaryosis and anisocytosis, with nuclei ranging from round to oval with one to two evident nucleoli. Cytoplasm was scanty and eosinophilic, with undefined cell borders. Focal areas of coagulative necrosis were present. The epidermis showed moderate irregular diffuse hyperplasia. Based on these findings, the tumor was characterized as a mammary adenocarcinoma. Metastatic nodules with the same cellular features were found in the lungs, liver and kidney. With these animals being kept as pets and becoming geriatric patients, it is expected that the number of neoplasias will increase considerably in the future and there is limited data about metastatic behaviour of tumor in chinchillas. To the author's knowledge, this is the first report of a mammary adenocarcinoma with metastatic sites in Chinchilla laniger. [ABSTRACT FROM AUTHOR] |
