LAUSR

Abstract Background Intraventricular tumors are rare, optimal treatment is not defined. Symptomatic patients often exhibit life‐threatening hydrocephalus. With several months time‐to‐effect after radiotherapy (RT), increased intracranial pressure is concerning. This increase in pressure can be overcome by ventriculoperitoneal shunting (VPS). Objectives Retrospective evaluation of outcome and complications in dogs and cats with intracranial tumors treated with either RT or VPS/RT. Animals Twelve client‐owned cats and dogs. Methods Dogs and cats with symptomatic intraventricular tumors treated with definitive‐intent RT or VPS/RT were included in a retrospective, descriptive case series. Complications, tumor volume evolution, time‐to‐progression, and survival time were determined. Results Twelve animals were included: 1 cat and 5 dogs treated with single‐modality RT and 4 cats and 2 dogs treated with VPS/RT. Neurological worsening seen in 4/6 animals during single‐modality RT and 2/6 died during RT (suspected brain herniation). All dogs with VPS normalized clinically by the end of RT or earlier. Complications occurred in 4/6 animals, all but 1 were successfully managed surgically. Imaging follow‐up in 8 animals surviving RT showed a marked decrease in tumor volume. Median survival time was 162 days (95% confidence interval [CI]: 16; infinity) for animals treated with RT and 1103 days (95%CI: 752; infinity) for animals treated with VPS/RT. Median time‐to‐progression was 71 days (95%CI: 7; infinity) and 895 days (95%CI: 704; infinity) for each group, respectively. Two dogs died because of intraventricular metastasis 427 and 461 days after single‐modality RT. Conclusions and Clinical Importance Ventriculoperitoneal shunting led to rapid normalization of neurological signs and RT had a measurable effect on tumor volume. Combination of VPS/RT seems to be beneficial.