[Renal pleomorphic sarcoma in four guinea pigs (Cavia porcellus)]

Renal tumours apparently are rare not only in cats and dogs, but also in guinea pigs and can be difficult to diagnose. The aim of this study is to describe the clinical, pathological and immunohistochemical findings in guinea pigs with renal tumours. Furthermore, the symptoms, diagnostic possibilities and therapy are compared with renal tumours in other small animals, including cats and dogs.

During a period of 4 years and 4 months the data of guinea pigs that had been presented in the clinic were retrospectively analysed. The analysis comprised guinea pigs that underwent a macroscopical and histopathological postmortem examination, and were diagnosed to have a renal neoplasm.

Four guinea pigs had a renal tumour. The percentage of renal neoplasms in relation to the overall necropsied carcasses and the number of organs originating from guinea pigs was 4.7 % and the percentage of renal neoplasms in relation to the overall diagnosed tumours of the abdominal and pelvic cavities was 30.7 %. Histology and immunohistochemistry revealed the presence of renal pleomorphic sarcomas in all four cases. In two of the four guinea pigs, the classical triad, as described for cats and dogs with renal tumours (weight loss, abdominal mass and haematuria), was observed. During clinical examination, a prominent, apparently painful abdominal mass in the region of the kidneys was palpable in all four cases. Applying radiography, the suspected diagnosis of a mass in the area of the kidney was confirmed in three cases, and in two animals the renal origin of the masses was determined by ultrasound examination.

Because a renal neoplasm is a pain-inducing disease with a high risk of metastases in domestic animals, a prompt nephrectomy should be performed when azotaemia is absent.