Neoplasias em ruminantes

Abstract

The term neoplasm means "new growth", and is a disease originating from damage to the cellular DNA. Such damage promotes mutation giving the cell a greater proliferative capacity and apoptosis evasion mechanisms. It can be benign or malignant, the latter being more invasive and harmful to the organism. The objective of this study was to discuss the most important neoplasms in ruminants and present the clinical and pathological aspects of five cases, three squamous cell carcinomas (SCC) and one malignant nerve sheath tumor (MTNS) in cattle and one squamous cell carcinoma in goats. SCC is one of the most frequently diagnosed neoplasms with exposure to ultraviolet radiation as an important factor in its occurrence. The periocular, ocular, vulvar and base of the horn of cattle are the most affected regions, and in sheep and goats, the ear, snout and perineum. The MTNS originate in the cells that make up the peripheral nervous tissue: Schwann cells, fibroblasts and/or perineural cells. In cattle with SCC lesions were identified on the back, vulva and periocular region. The SCC identified in the goat stood out for its location at the base of the horn, large proportions and infiltrative capacity. The swelling had appeared six months before. The tumor was removed, but after 15 days the animal died. The MTNS diagnosed in the bovine began as a small, progressively growing swelling that at the time of the physical examination measured approximately 30 centimeters in diameter. The pre-scapular and pre-crural lymph nodes were stiff and enlarged. The animal was referred to the HV/UFPB for tumor resection. The cases described were seen in the field. Clinical examination and collection of material for cytological and histopathological examination were performed for diagnosis. In the case of suspected MTNS, immunohistochemistry and necroscopic examination were also performed. The exams performed proved the neoplastic character of the lesions. Immunohistochemistry showed positive immunolabeling for S-100 antibodies and revealed that the neoplastic cells originated from peripheral nerve. Five months after excision the animal presented respiratory distress and was euthanized in extremis. At necropsy multiple metastatic nodules were observed in the lungs. The occurrence of four animals with SCC proves the higher frequency of this tumor, and the locations in cattle are similar to those reported in the literature. Most owners do not have access to information about these diseases, and even acquire animals with neoplastic lesions. In the beginning of the problem they start the treatment for a conventional wound, which worsens the prognosis, delaysthe establishment of correct therapies and even the discarding of the animal. The severity of the lesions in the animals treated demonstrates the producers' delay in seeking veterinary assistance. The reports show the high incidence of neoplasms in ruminants and their severity, as well as the need for dissemination of knowledge among producers. The dissemination of information on neoplasms in production animals is important so that it is possible to make an early diagnosis of these diseases and reduce the losses generated by them.