Bilateral ovarian adenocarcinoma in a geriatric Shih Tzu

A 15 year old female intact Shih Tzu was presented due to vaginal discharge of 4 day duration that had been recurring for over 1 year. She had a history of an open pyometra twice in the past year. Ovariohysterectomy had not been pursued, due to owner’s concern for anesthetic risk. On presentation, the patient was moderately thin, had serosanguinous vaginal discharge, a swollen vulva, and a positive flagging response; physical examination was otherwise unremarkable. Vaginal cytology revealed primarily intermediate cells with few parabasal cells. Vaginal cultures revealed growth of Enterococcus faecalis, Escherichia coli, and Staphylococcus pseudointermedius. Progesterone concentration was 0.79 ng/ml. Transrectal ultrasonography revealed cystic structures on both ovaries. Followup examinations within next 2 weeks revealed similar findings on vaginal discharge and cytology, and progesterone concentrations rose slowly to 2.28 ng/ml. Due to the abnormal ovarian findings and potential for hyperestrogenism, ovariohysterectomy was pursued. Preoperative bloodwork revealed a mild leukocytosis characterized by a neutrophilia with a mild left shift. Histopathology of reproductive tract revealed bilateral ovarian adenocarcinoma, severe, diffuse, chronic cystic endometrial hyperplasia, and mild pyometra. Epithelial tumors, including ovarian adenomas and adenocarcinomas, were the most common primary ovarian tumor in dogs (46%), with adenocarcinomas making up 20% of canine ovarian tumors. ¹ The patient recovered without incident and was discharged to the care of her owner. Followup examination 3 weeks postoperatively, including thoracic radiographs and abdominal ultrasonography, revealed no evidence of metastasis. This case presented a unique abnormal estrous cycle secondary to a neoplastic process in a geriatric bitch with an open pyometra.

Keywords: Ovarian adenocarcinoma, geriatric dog, hyperestrogenism

References

1.Arlt S, Haimerl P: Cystic ovaries and ovarian neoplasia in the female dog - a systematic review. Reprod Domest Anim 2016;51:3-11.

This manuscript was originally published in the journal Clinical Theriogenology Vol 12(3) Sept 2020.  Clinical Theriogenology is the official journal of the Society for Theriogenology (SFT) and the American College of Theriogenologists (ACT).  This content has been reproduced on the IVIS website with the explicit permission of the SFT/ACT.