A Dalmatian was presented with a subcutaneous swelling in the dorsal midline between the eyes. No opening in the skin was identified at the dorsal nasal planum and there was no discharge. Positive contrast sinography showed contrast material filling a cyst that extended to the frontal bone. At surgery, the cyst had a tubular shape and was embedded in a fibrous dermal tissue strand running into the bony nasal septum. The nasal dermoid sinus cyst was surgically removed by limited dorsal rhinotomy, followed by excision of the remaining strand from a bony recess in the lamina perpendicularis ethmoidalis. It is proposed that this nasal dermoid cyst that extends through the frontal bone with no sinus tract is classified as a type V subtype c.