May 13, 2012

Canine Ovarian Remnant Syndrome


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 RMVanleeuwen 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
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 occur




      by : Bruce E Eilts

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