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

    • Enzymes present to make adrogens, not estrogens

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

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