Page 1010 - Small Animal Internal Medicine, 6th Edition

982 PART VIII Reproductive System Disorders

can begin within days after surgery. In bitches, signs reported
include attraction of male dogs, swelling of the vulva, mucoid
VetBooks.ir to sanguineous vulvar discharge, passive interaction with
male dogs, and flagging; some even allow copulation. Of
note, the signs are usually cyclical or periodic (i.e., every 6
months) rather than constant as occurs with chronic ves-
tibulovaginitis or exogenous estrogen exposure. In queens,
signs reported include vocalization, lordosis, restlessness,
head rubbing, rolling, tail deviation, and treading the hind
limbs; the queen may allow copulation. Queens demonstrate
typical behavioral signs of estrus in a cyclical (seasonally
polyestrous) fashion.
The most common cause is a previous failure to remove
both ovaries completely. There is no correlation with age at
ovariohysterectomy, difficulty of surgery, obesity of patient,
or experience of the surgeon. The presence of anatomically
abnormal ovarian tissue (fragmentation into the broad liga-
ment) is possible but uncommon, and a supernumerary
ovary is very rare. Experimentally, functionality returns to
FIG 55.37 ovarian tissue removed from its vascular supply and replaced
Postoperative image of corrected redundant dorsal vulvar into or onto the lateral abdominal wall. The clinician needs
hooding (Fig. 55.35). to consider multiple differentials, including inflammation or
infection of the genitourinary tract, vaginal hemorrhage due
Therapy of urogenital neoplasia can include surgery, che- to foreign body, trauma, a uterine stump granuloma or pyo-
motherapy, or both. metra, neoplasia of the genitourinary tract, vascular anoma-
If no anatomic, foreign body, infectious, granulomatous, lies of the genitourinary tract, a coagulopathy, exogenous
or neoplastic cause can be discerned, oral estrogen replace- estrogen administration, and an endogenous extraovarian
ment therapy is often helpful in establishing normal mucosal source of estrogen associated with adrenal pathology (rare).
integrity and eventual normalization of the vaginal vault. The Exposure to exogenous estrogen is not uncommon in small
condition is similar to atrophic vaginitis in women. The dogs whose owners use transdermal hormone replacement
prevalence of atrophic vaginitis is particularly high among therapy, usually on their forearms. In this case, the signs of
postmenopausal women who experience decreased ovarian hyperestrogenism would be more constant than the cyclical
estrogen production. This common menopausal condition is nature of an ovarian remnant. Ovarian remnants can undergo
caused by estrogen-related changes to the vaginal epithelium neoplastic transformation; external signs of hormonal influ-
and can adversely affect quality of life. Women improve with ence then become chronic rather than episodic (Fig. 55.38,
vaginal estrogen application, difficult in the dog. Oral dieth- A, 55.38, B).
ylstilbestrol (compounded DES) or an FDA-approved estriol A minimum database should be performed: CBC and
(Incurin [Merck]; off label) is advised in bitches. The dose is serum chemistries, including a urinalysis (preferably
empirical and usually the same as used for urinary inconti- acquired by cystocentesis), and culture or culture “if indi-
nence due to sphincter incompetence (DES 0.035 mg/kg PO cated” of the urine is advised. Pancytopenia is possible from
every 3-4 days; Incurin 1-2 mg PO q24h, taper as possible). estrogen toxicity. Critical observation of behavioral and
Several weeks of therapy may be required before improve- physical signs of estrus together with vaginal cytologic analy-
ment is recognized. Side effects are uncommon; mild over- sis and/or measurement of serum progesterone or estradiol
dosage results in signs of proestrus (attraction to male dogs, concentrations can confirm the presence of functional
vulvar swelling); myelosuppression is highly unlikely if the ovarian tissue. Vaginal cytology will identify estrogen effect:
dosage is conservative as suggested. vaginal mucosal cornification is a bioassay for elevated
plasma estradiol concentrations (see Chapter 54). Note that
OVARIAN REMNANT SYNDROME/ peak estradiol concentrations triggering behavioral estrus
HYPERESTROGENISM range from 20 to more than 70 pg/mL; however, vaginal
Ovarian remnant syndrome (ORS) causes behavioral and/or cytology findings closely correlate with serum estradiol, and
physical signs of estrus in a bitch or queen having previously this study is much less expensive to perform. A serum pro-
undergone ovariohysterectomy. It is caused by the presence gesterone level >2.0 ng/mL (measured 1-3 weeks after
of functional residual ovarian tissue and is reported to be behavioral estrus) is consistent with functional luteal tissue.
responsible for 17% of all postovariohysterectomy complica- GnRH (50 µg IM bitch, 25 µg IM queen) or hCG
tions. It is more common in cats. No breed predisposition or (500-1000 IU IM) can be used to attempt to induce ovula-
geographic distribution has been reported. The signs of estrus tion or luteinization for diagnostic purposes or to end estrus.
usually occur months to years after ovariohysterectomy but Serum progesterone is measured 2 to 3 weeks later; this is