Sebaceous gland neoplasms are one of the cutaneous neoplasms in the canine. A 5-year-old ovary hysterectomy female, mixed breed terrier was referred to veterinary clinic of the Islamic Azad University, Shahrekord Branch due to a mass in the head area. The morphological characteristics of the lesion revealed an encapsulated, round, solitary yellowish-white mass, relatively soft consistency with an approximate diameter of 9 mm in the right midline the forehead and calvarium area with minor hair loss. Next, a complete excisional biopsy was done for pathology diagnosis. After dehydration, clearing and impregnated with paraffin, a tissue sample was stained with Hematoxylin and Eosin method. The microscopic characteristics of the tumor mass showed two different cell types, including mature sebaceous gland cells with vacuolated cytoplasm and small hyperchromic nucleus, and several rows of basaloid cells around sebaceous glands without mitotic division that were not adjacent to hair follicles. Inside several follicles, sections of the middle parts of demodex's body were observed. Our report is a unique example of sebaceous adenoma with infection of hair follicles with demodex mites in an ovariohysterectomy in a female dog. پرونده مقاله