Successful long-term outcome with radiation and prednisolone following a postoperative feline vertebral angiomatosis relapse

CASE SUMMARY: A 1-year-old male castrated domestic shorthair cat was presented to the Ontario Veterinary College for a week-long history of lethargy and reluctance to walk. CT and MRI revealed a monostotic T5 compressive vertebral lesion that was excised in surgery via pediculectomy. Histology and advanced imaging were consistent with feline vertebral angiomatosis. The cat relapsed both clinically and on CT 2 months postoperatively and was therefore treated with an intensity-modulated radiation therapy protocol (45 Gy over 18 fractions) and tapering doses of prednisolone. On follow-up CT and MRI at 3 and 6 months post-radiation, the lesion was static and then improved at 19 months post-radiation, with no signs of pain reported. RELEVANCE AND NOVEL INFORMATION: To our knowledge, this is the first described case of a postoperative relapse of feline vertebral angiomatosis treated with radiation therapy and prednisolone with a successful long-term follow-up.