Abstract

A 13-year-old female clouded leopard (Neofelis nebulosa) housed at the Rosamond Gifford Zoo was evaluated for a two-day history of lethargy and inappetence. Upon visual exam, the animal was unwilling to move and showed signs of abdominal discomfort. She was immobilized with a medetomidine/ketamine combination and maintained on isoflurane for evaluation. Physical exam findings included thin body condition, a moderate degree of muscle atrophy, 10% dehydration, alopecia of the distal tail, a rigid spine, and a firm, irregular mass in the mid-abdomen. Blood was collected for a complete blood cell count and serum biochemistry. Abdominal radiographs confirmed the presence of a mass in the mid-abdominal region, which appeared to be related to the spleen. Both kidneys were smaller than normal, and the left kidney was irregular in shape. Ultrasound examination of the abdomen confirmed the presence of the mass and allowed a higher degree of suspicion that the mass was splenic in nature. A fine needle aspirate of the mass was performed and yielded a cytologic diagnosis of lymphoma based on the presence of a prominently dominant population of lymphoblasts admixed with a reactive population of inflammatory cells.

Results of the complete blood cell count were not available and the biochemistry analysis was largely normal except a marked azotemia. Three treatment options were explored: 1) euthanasia, 2) chemotherapy with adriamycin, cytotoxin and prednisone which is currently the most successful treatment utilized in domestic cats for lymphoma and 3) treatment with prednisone alone. The following day, the animal was started on prednisone therapy at 2 mg/kg and cephalexin at 10 mg/kg as a prophylactic measure. During the following month, the animal’s activity increased and her appetite was normal; however, she exhibited a progressing degree of muscle wasting. One month after the initiation of prednisone, the cat’s appetite became irregular. Oral therapy with sucralfate at 1 gram twice daily was initiated. The cephalexin was discontinued at this time, as this drug is reported to cause nausea and anorexia in domestic cats. Over the next month, the cat’s level of activity decreased significantly, and weight loss progressed. Serial urinalyses performed on samples obtained opportunistically showed a marked bilirubinuria. Two months after the initial diagnosis, the cat was immobilized for further evaluation of its hepatic/renal function and to reevaluate the progression of the splenic lymphoma. Due to the animal’s poor body condition and poor response to therapy, euthanasia was elected.

Significant gross necropsy findings included generalized lymphadenopathy, a multifocally discolored spleen with poorly demarcated, coalescing 1–3-mm white areas, and a liver with poorly demarcated, irregular, multifocal 1–3-mm white areas and well-demarcated, spherical, white to pink multifocal nodules. The medullary cavity of the femur was filled with a dark red, firm material, with multifocal, poorly circumscribed 1–3-mm white areas. The kidneys contained circular, cortical, fluid-filled cavities. The subcutaneous tissue was bright yellow.

Histopathologic diagnosis indicated that the architecture of the lymph nodes had been replaced by a sheet of small- and medium-sized lymphocytes in a coalescing follicular arrangement. The spleen was multifocally infiltrated with small- and medium-sized lymphocytes, similar to those found in the lymph nodes, as was the liver. The renal cysts were thought to be an incidental finding. The majority of the bone marrow cells were of the same neoplastic population as seen in the liver, spleen and lymph nodes. A final diagnosis of multicentric lymphoma was concluded based on histopathologic findings.