Abstract
A 7-month-old femal Rhodesian Ridgeback was referred for the cervical subcutaneous mass to the Veterinary Medical Center of the University of Tokyo. Thirty days before the first admission, the cervical mass was surgically removed by a practitioner but the mass with a cyst recurred at the surgical site soon after the removal. On physical examination, the mass with a size approximately 10cm in diameter was palpated on the dorsal midline of the neck. Serous fluid was drained from the selfscratched wound of the mass. The patient did not show pain by palpating the mass and was otherwise healthy. There were no abnormal findings on blood examination and on cervical and thoracic radiography. From above results, dermoid sinus of a Rhodesian Ridgeback was suspected. Magnetic resonance (MR) images revealed that the sinus seemed to extend ventrally to the nuchal ligament. After the MR imaging, the mass with the sinus reaching to the nuchal ligament was completely removed. On histology, the mass was inflammatory granulation tissue and the hair follical was demonstrated in the sinus, thus diagnosed as dermoid sinus.
