Canine Ovarian Remnant Syndrome
(Estrus after Ovariohysterectomy)
Problem:
- Signs of 'estrus' after ovariohystectomy
- Swollen vulvua - common
- Vulvar discharge - common
- Attracting male dogs
- Signs of pseudogenetra or pseudopregnancy 2 months after the episode of 'estrus'
Questions:
- Has an ovariohysterectomy been performed?
- History - how long has the dog been owned
- Known ovariohysterectomy?
- Where?
- Who? - It can happen to specalaists!
- Are there other sources of estrogen?
- Exogenous
Why?
- Ovarian remnant left at surgery - faulty technique?
- 17% of post ovariohysterectomy complications in one study were due to ovarian remnants.
- May be anomalous accessory ovarian tissue in the broad ligament
When?
- 15.5 months average post surgery (3 months to 5 years)
- Mean interestrus interval 8.8 months
Diagnostics:
- Vaginal cytology - should be cornified cells if there is any estrogenic stimulation endogenous or exogenous).
- If there is an ovarian source, estrogen should decline and cornification subside in 9-20 days
- If the estrogen is exogenous, the cornifcation will subsist.
- Progesterone - Progesterone should be high for approximately 2 months after the signs of estrus regress if there is an ovarian source of estrogen.
- Submit a blood sample for progesterone around 2 weeks after estrual signs end.
- There should be a 'normal' luteal period if an ovarian remnant is present.
- LH testing - Löfstedt RM, Vanleeuwen JA. Evaluation of a commercially available luteinizing hormone test for its ability to distinguish between ovariectomized and sexually intact bitches. J Am Vet Med Assoc. 2002 May 1;220(9):1331-5.
- Ovariectomy results in loss of negative feedback on LH (via GnRH?) resulting in a rise in fast and long term rise in LH.False positive occur if the bitch is at the natural LH peak.
- Normal LH is 'low'.
- Single high serum LH concentration was not a reliable indicator of ovarian removal
- Sensitivity (98%) but moderate specificity (78%) because of a high frequency of false-positive test results (actual LH peak)
- A single low serum LH concentration was an excellent indicator that a bitch was sexually intact.
- The LH test results were positive within 10 days after ovarian removal
- Remained high in bitches from which ovaries had been removed > 5 years previously.
- Excellent agreement in test interpretation within and among evaluators and over a 6-hour time span.
- Ultrasound
- Hard for most to identify ovaries (need to scan repeatedly over time to identify. See it in the picture below?
- Follicles may be seen on ovaries.
- Corpora lutea do not always appear hyperechoic
- 11/12 scanned (21 total in study) in one study had suspected ovaries (JAVMA 236:548-551, 2010)
- 9/12 correctly identified (presence or absence)
- 3/12 remant found at surgery, but not seen by US
- Treatment - Surgery
- Location
- 6/21 - left pedicle
- 13/21 - right pedicle
- 2/21 - both pedicles
Other sources of estrogen
Exogenous
- Topical estrogen creams and sprays used by menopausal women
- Can pass estrogen to dog, and is becoming more common
- Usually small breed dogs that are carried around
Click on the any picture above to see a web article on Evamist
- Ingestion of any estrogenic substances - do a complete inventory of household products
- Endogenous estrogen production
- Adrenal - not common
Treatment
- Remove exogenous estrogen if documented
- Surgery
- Document that the presence of an ovarian remnant is highly likely
- Best done in diestrus - less blood than in 'estrus'
- 35% had bilateral ovarian remnants at the pedicle
- 46/46 dogs with problems had remnants in the ovarian pedicle (extreme exploration probably not needed)
- JAVMA study
- 6/21 - left pedicle
- 13/21 - right pedicle
- 2/21 - both pedicles
- Submit sample for histopathology
- If luteal tissue is present on the removed remnant, false pregnancy may occurby : Bruce E Eilts
