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822 Prolonged Estrus

Prolonged Estrus Bonus Material Client Education
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BASIC INFORMATION
• Abdominal ultrasonography to look for
endogenous sources of estradiol
Definition ○ Identification of abnormal ovarian structures:
• In the dog, combined proestrus and estrus anechoic spherical regions in the ovary (fol-
of > 6 weeks or a cytologic estrus that lasts licles) or mixed echogenicity of a tumor
for > 21 days ○ Identification of ovarian remnant in an
• In the queen, estrus lasting longer than 10 ovariohysterectomized animal
days is considered prolonged.
• Ovarian remnant syndrome (ORS) refers to Advanced or Confirmatory Testing
clinical signs indicating functional ovarian • Vaginoscopy (p. 1184) to rule out foreign
tissue in a previously ovariohysterectomized body and vaginitis
bitch or queen and is discussed in detail on • Exclusion of abnormal karyotype
p. 732. • Coagulation panel to rule out coagulopathy
Synonyms PROLONGED ESTRUS Abdominal ultrasonography TREATMENT
Persistent estrus (heat), nymphomania of a bitch with ovarian cysts that caused prolonged
proestrus. (From Feldman EC, et al: Canine and feline Treatment Overview
Epidemiology endocrinology and reproduction, ed 3, St. Louis, 2004, Treatment of abnormal estrus consists of remov-
SPECIES, AGE, SEX Saunders.) ing the source of estradiol. For persistent estrus,
Female dogs and cats > 4 months of age induction of follicular luteinization with subse-
Etiology and Pathophysiology quent monitoring of progesterone concentrations
GENETICS, BREED PREDISPOSITION Prolonged estrus: and vaginal cytology for signs of diestrus or
Asian cat breeds (e.g., Siamese) are predisposed • Cause depends on source of persistently cir- alternatively performing an ovariohysterectomy
to overlapping follicular waves that can present culating estradiol (exogenous or endogenous).
as prolonged or persistent estrus. • Estrogen-secreting follicular cysts or granulosa Acute and Chronic Treatment
cell tumors can result in persistent estrus. Medical:
RISK FACTORS ○ Follicular cysts have been reported to • Follicular cysts in dogs and cats can be treated
Young and very old bitches; previous history occur in 3%-62% of dogs with ovarian with GnRH 25 mcg/dose IM; use 2.2 mcg/
of follicular cysts; abnormal karyotype cystic disorders. These cysts occur as single kg if > 11 kg or with human chorionic
or multiple, thin-walled structures that gonadotropin (hCG) 500-1000 IU/dose IM,
ASSOCIATED DISORDERS contain a clear, serous fluid. which results in luteinization of the follicles.
Secondary to chronic estrogen exposure, bone • In the queen, persistent estrus may result • Monitor serum progesterone, and perform
marrow suppression, uterine disease, and from the overlapping waves of maturing a vaginal cytologic exam (p. 1183) weekly
mammary disease may occur. ovarian follicles, resulting in prolonged high after GnRH or hCG administration; monitor
concentrations of estradiol. for signs of diestrus or anestrus.
Clinical Presentation Surgical:
HISTORY, CHIEF COMPLAINT DIAGNOSIS • When genetic qualities of the dam are not
• More than 21 days (dog) or 10 days (cat) superior, ovariohysterectomy is the treat-
of behavioral estrus Diagnostic Overview ment of choice after reduction of current
○ Estrous behaviors in the bitch include The diagnosis is suspected based on the presence hyperestrogenic state.
receptivity to males, vulvar edema, and of estrous behaviors in an ovariohysterectomized
serosanguineous vulvar discharge. In animal or prolonged in an intact bitch or queen. Possible Complications
the queen, lordosis and vocalization Confirmation requires identification of the Pyometra sequelae (p. 854):
occur. source of estradiol (exogenous or endogenous) • Progesterone promotes endometrial growth
• History of use of estrogens to treat urinary and functional ovarian tissue. and glandular secretion while decreasing
incontinence or deslorelin (gonadotropin- myometrial activity. Cystic endometrial
releasing hormone [GnRH] agonist) for Differential Diagnosis hyperplasia and accumulation of uterine
contraception • Persistent proestrus secretions result, providing an excellent
○ Recent use of estradiol cypionate as an • Split estrus (proestrus without subsequent environment for bacterial growth.
abortifacient for unintended breedings estrus followed by a normal cycle in about • Chronic estradiol production by the cystic
is sometimes reported, although not 4 weeks) follicles upregulates progesterone receptors
recommended. • Recurrent estrus (low progesterone level or in the uterus. This enhances the effect of
premature luteal failure) the progestins produced after treatment to
PHYSICAL EXAM FINDINGS • Pyometra luteinize the cystic follicles.
• Bitch or queen may be in good health. • Vaginitis Myelotoxicosis sequelae:
• Chronic exposure to estrogen can result • Coagulopathy • Chronic endogenous or exogenous estradiol
in disease states manifesting as cystic • ORS may induce production of myelopoiesis-
endometrial hyperplasia-pyometra complex, inhibitory factor with subsequent myelosup-
bone marrow suppression (anemia, agranu- Initial Database pression (causing anemia, thrombocytopenia,
locytosis, thrombocytopenia), mammary • CBC (anemia, thrombocytopenia), serum leukopenia) and a poor prognosis if untreated.
and uterine neoplasia, and endocrinologic biochemistry profile, urinalysis
alopecia. • Exfoliative vaginal cytologic exam indicative Recommended Monitoring
• Palpable unilateral abdominal mass (ovarian of estrus: > 90% cornification of epithelial Monitor signs of estrus, which should subside
tumor) cells (p. 1183) within 5-7 days of treatment.
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