Spontaneous splenic hemangiosarcoma in pet guinea pigs (Cavia porcellus): five cases (2007-2021)

Background: Spontaneous hemangiosarcoma in guinea pigs has only been reported twice in the literature. This study aims to better characterize the prevalence, clinical presentation, treatment, and outcome of this rare disease in guinea pigs.Methods: Medical records (2007-2021) from four referral centers were reviewed. Guinea pigs with a histopatho-logical diagnosis of hemangiosarcoma performed by a board certified veterinary pathologist were selected for inclusion.Results: Of 3994 guinea pigs examined, five were included in the study. The median age at the time of diagnosis was four years (4-6 years). Four of the five patients presented with dysorexia. An abnormal spleen was palpated in all animals and confirmed by ultrasonography. Only one guinea pig had presurgical radiographs to evaluate for metastasis before splenectomy. One patient was euthanized after surgery, while the others died two weeks, six months, 15 months and 49 months after the procedure. One patient was also treated with Trametes versicolor extracts as an adjuvant antineoplastic therapy. The median survival time was six months.Conclusion and clinical relevance: Abdominal palpation and ultrasound can provide a presumptive diagnosis of splenic enlargement. Splenectomy has proven to be a feasible surgical procedure for the treatment of splenic hemangiosarcoma, potentially combined with adjuvant anticancer therapies. The variable survival after splenec-tomy reported in the five cases here is challenging to interpret because of the different anesthetic techniques and comorbidities. Further research is needed to improve understanding of the biological behavior of this neoplasm as well as the benefits of splenectomy and adjuvant therapies.