A 7-year-old male intact border terrier (8.5 kg) was presented with a large, painless mass apical to the right maxillary incisors. Diagnostic imaging and histopathology confirmed the diagnosis of periapical cyst due to a nonvital maxillary incisor. Extensive cysts are often multilocular and therefore difficult to debride without risk of iatrogenic damage. Complete resection can cause damage to adjacent structures and may compromise function. Due to the large size of the cyst, it was decided to perform staged treatment with extraction of the nonvital tooth and marsupialization. Following marsupialization, gradual bone regrowth caused size reduction. The stoma from the marsupialization was kept open for 8.5 months before the cyst was curetted and the wound closed. Complete obliteration of the cyst cavity was seen at short- and long-term follow-up examinations (7 and 24 months after curettage, respectively).