M.D. Barros; G.A. Gonçalves; A.P. Gonçalves; A.M.R. Ferreira
Lymphoma is the most common malignancy in the domestic ferret and the third most common neoplasm overall (Willians & Weiss, 2004). Lymphoma has been reported to involve many organs, including the cranial mediastinal lymph nodes and the thymus (Taylor T.G. & Carpenter J.L. 1995). Virus-induced malignant lymphomas have been demonstrated in many species and have been extensively documented in cats (Erdman et al., 1992). In cattle and cats, some types of lymphoma are related to oncogenic retroviruses (Erdman et al., 1996), but in ferrets (Mustela putorius furo) no viral etiology has been established (Erdman et al., 1992). In the most commonly seen form of lymphoma, the lymph nodes are the most affected sites, resulting in peripheral lymphadenopathy, with visceral spread and organ failure occurring late in the course of the disease (Willians & Weiss, 2004). The objective of this study was to describe clinical and pathologic findings in ferrets with lymphoma examined between 2000 and 2008 at the Policlínica Veterinária Ypiranga--Rio de Janeiro, RJ.
Materials and Methods
The material was obtained from the clinical records of the Policlínica Veterinária Ypiranga from 2000 to 2008. Ferrets were included in the study only if the diagnosis was confirmed by means of histologic examination of biopsy specimens. Age, sex, history, clinical signs, pathologic abnormalities and results of histologic examination were the information collected from the records.
Five ferrets met the criteria for inclusion in the study. Of 136 ferrets in the database from 2000 to 2008, 5 were diagnosed with lymphoma (3%). There were 3 male and 2 female. All of the ferrets aged 5 to 7 years old and all have been neutered. Clinical histories were often nonspecific, including a history of anorexia, weight loss and lethargy. Clinical findings: Palpable splenomegaly was observed in 4 ferrets. Peripheral lymphadenopathy was detected in the 5 animals. Two ferrets had visceral lymphadenopathy with multiple palpable masses (multicentric distribution). Two ferrets had also clinical signs and histological abnormalities related to adrenal gland disease. Only two ferrets had a completely histological examination and the lymphomas were interpreted to be diffuse and with a high mitotic index. The five animals did not receive any treatment.
Discussion and Conclusions
Lymphoma is one of the most commonly reported neoplasm in ferrets. In this study, history, clinical findings, and pathologic abnormalities were related to age. Splenomegaly, which was observed in 80% of the ferrets with lymphoma in this study, is a nonspecific finding, and is a common finding in ferrets with numerous other illnesses (Ferguson, D.C. 1985). Disseminated lymphoma was common in these ferrets and the most were reported in older ferrets and localized to the abdominal organs (Erdman et al. 1996). Visceral and mesenteric lymph nodes and the liver are common sites for lymphoma, intestinal lymphoma is uncommon (Hoefer H.L. 2004). Hepatomegaly, splenomegaly, or enlarged lymph nodes may be detected on physical examination (Batchelder, M.A. et al. 1996). In this study the five ferrets have been demonstrated anorexia, weight loss, lethargy and peripheral lymphadenopathy, the most common clinical findings in this pathology (Willians & Weiss, 2004). GIS (Granulomatous Inflammatory Syndrome) may produce gross lesions identical to lymphoma, but it has been linked to hypergammaglobulinemia in ferrets and it is a differential diagnosis for this new ferret disease (Perpiñán & López 2008). The differential diagnosis of lymphoma includes neoplastic and inflammatory diseases that involve lymphatic organs and the histological examination is definitive for the final diagnostic. Lymphomas accounted for 78% of hemolymphatic tumors diagnosed (Xiantang et al. 1998). Clinical and pathologic features linked with age should be considered when evaluating diagnostic for ferrets with lymphoma. The potential viral nature of certain lymphomas in ferrets warrants further investigation.
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