Spontaneous occurrence of malignant lymphoma in sheep: case report / Ocorrência espontânea de linfoma maligno em ovelha: relato de caso

ABSTRACT

There are very few reports of lymphoma in sheep in the literature. Therefore, the aim of the present study was to report the prevalence of this disease among sheep cared for in the Clinic of Cattle in the Campus Garanhuns of the Federal Rural University of Pernambuco (UFRPE). The results were obtained from a four year old sheep (weight 40 kg) that had been reared in a semi-intensive system. The owner reported that he had acquired this animal three months earlier from another herd and that, one month later; he had noticed that the animal was apathetic, no appetite and distanced itself from the herd. The animal was treated unsuccessfully on the farm. The animal exhibited clinical signs of apathy, tachycardia, cachexia and anorexia, as well as ruminal and intestinal hypomotility. The hemogram showed evidence of leukocytosis by neutrophilia, with the presence of deteriorated leukocytes in the blood smear. The serology (IDGA) for the enzootic bovine leukosis virus was negative. The ultrasound confirmed severe lung disease. The animal died after seven days. In the necropsy there was a mass in the subcutaneous tissue adhered to chest sternal there was a notable increase in the volume adhered in the external caudal subcutaneous region, with nodular characteristics and a whitish coloration. Identical, although smaller, nodulations were visualized in the serous membrane of the reticulum and the abomasum, with metastases in the kidneys, omentum, mesenteric lymph nodes, diaphragm, heart and lungs. The histopathology revealed atypical mantle structures,with multiple vacuoles and interspersed fibrous stroma. The tumoral cells were small, round, basophilic, with scarce cytoplasm and a large, round nucleus, with hyperchromatic qualities, dense chromatin and rare mitosis. The results of the present study confirm that this was a case of atypical lymphosarcoma in the sheep in question.

RESUMO

Os relatos na literatura de linfoma em ovinos são escassos, logo o objetivo deste trabalho é relatar a ocorrência dessa doença em uma ovelha atendida na Clínica de Bovinos, Campus-Garanhuns/ UFRPE. Os achados foram obtidos de uma ovelha mestiça de quatro anos, pesando 40 kg, criada em sistema semi-intensivo. O proprietário relatou que adquiriu esse animal há três meses de outro rebanho e que há dois observou que o animal ficou apático, com perda do apetite e separado do rebanho, foi medicado na propriedade sem sucesso. Clinicamente apresentou um quadro de apatia, taquicardia, caquexia, anorexia, bem como hipomotilidade ruminal e intestinal. No hemograma evidenciou-se leucocitose por neutrofilia, com presença de leucócitos degenerados no esfregaço sanguíneo. A sorologia (IDGA) para vírus da Leucose Enzoótica Bovina foi negativa. Além desses achados, a ultrassonografia revelou um comprometimento pulmonar grave. O animal veio a óbito após sete dias. Na necropsia observou-se uma massa no tecido subcutâneo, aderida à região torácica caudal esternal, firme com características nodular e de coloração esbranquiçada. Nodulações idênticas e de tamanhos menores foram visualizadas na serosa do retículo e abomaso, com metástases nos rins, omento, linfonodos mesentéricos, diafragma, coração e pulmão. A histopatologia revelou estruturas atípicas disposta na forma de manto, com múltiplos vacúolos, com estroma fibroso entremeado. As células tumorais caracterizam-se por serem pequenas e arredondadas, basofílicas, com citoplasma escasso, núcleo grande e redondo, hipercromático, com cromatina densa e com raras mitoses. Estes achados indicam uma forma de linfoma espontâneo em ovelha.