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495.e2 Hyperestrogenism, Canine

Hyperestrogenism, Canine Client Education
Sheet
VetBooks.ir Initial Database

• Spayed females: may be associated with
BASIC INFORMATION
diethylstilbestrol or estradiol supplementation • A complete anamnesis is crucial.
Definition for urinary incontinence, or with remnant ○ Confirm sexual status (apparent neutered
Cutaneous (e.g., noninflammatory alopecia) ovaries. dog may in fact be a bilateral cryptorchid).
and/or systemic clinical signs (e.g., myelosup- ○ Drug administration (e.g., oral or inject-
pression) resulting from excessive endogenous HISTORY, CHIEF COMPLAINT able estrogens for urinary incontinence)
or exogenous estrogens The animals are typically presented for a ○ Are dogs in contact with women receiving
nonpruritic alopecia and occasionally for a topic estrogens?
Epidemiology testicular mass or prolonged estrus. • Evaluation of endocrine function to rule out
SPECIES, AGE, SEX hypothyroidism and hyperadrenocorticism
• More common in middle-aged to older, intact PHYSICAL EXAM FINDINGS • Abdominal ultrasound: females (ovarian
dogs • The most characteristic sign is a symmetrical, cysts), males (retained testes)
• Intact male dogs with testicular Sertoli cell noninflammatory, nonpruritic alopecia, • CBC (myelosuppression possible)
tumors, particularly in cryptorchid males which begins in the perineal region, inner
(p. 962) thighs, and ventral abdomen, progressing to Advanced or Confirmatory Testing
• Intact females with functional ovarian tumors the entire trunk and proximal extremities • Skin biopsies: histopathology findings are
or cystic ovaries or female dogs supplemented but sparing head and distal extremities. not specific and do not allow differentiation
with estrogens for treatment of urinary • In males, macular melanosis may develop from other endocrine or atrophic disorders.
incontinence or unwanted pregnancy on the scrotum and the perineal region. Most hair follicles are in late catagen phase
• Dogs of any age or sex in contact with • A linear preputial dermatosis, characterized or telogen phase. If estrogenic stimulation
women receiving treatment with topical by an erythema or hyperpigmented line on persists, the epidermis and apocrine glands
estrogens the prepuce, is occasionally seen. This appears may become atrophic. If there is secondary
• Reported in hermaphrodite dogs to be a fairly specific marker for testicular infection, inflammatory infiltrates can be
• A single case has been reported in a cat neoplasia, particularly tumors that produce seen.
• Common in intact female ferrets estrogen. • Histopathology of testicular tumors: confirm
• Secondary pyoderma occasionally can be Sertoli cell tumor
GENETICS, BREED PREDISPOSITION seen. • Preputial cytology: keratinization of the
• Higher incidence of Sertoli cell tumors • In females, vulva and nipple enlargement is preputial epithelium in Sertoli cell tumor
among collies, Shetland sheepdogs common. associated with hyperestrogenism
• Described in a pseudohermaphrodite female • In male dogs, feminization may occur as
toy poodle with polycystic ovaries evidenced by gynecomastia (nipple enlarge- TREATMENT
ment, pendulous penile sheath). Most cases are
RISK FACTORS caused by Sertoli cell tumors. Testicular tumors Treatment Overview
• Hyperestrogenism occurs in 20%-30% of can be retained or located in the scrotum. The The main goal is to remove the source of
dogs with Sertoli cell tumor contralateral testis is usually atrophic. endogenous or exogenous estrogen.
• About half of Sertoli cell tumors occur in • Bone marrow suppression (thrombocytope-
cryptorchid testes nia, neutropenia, and anemia) induced by Acute General Treatment
• Risk of Sertoli cell tumors is ≈20 times higher estrogen is rare but can be life-threatening. • In cases of endogenous hyperestrogenism,
in cryptorchid testes Evidence of anemia, petechial or ecchymotic treatment of choice is gonadectomy. Remnant
• Right testes are affected twice as often as left hemorrhage, or secondary infection may be ovaries need to be removed surgically.
testes. identified in such cases. • In cases of exogenous hyperestrogenism, the
administration of systemic estrogens must be
ASSOCIATED DISORDERS Etiology and Pathophysiology stopped, or contact with topical estrogens
Pancytopenia, alopecia Estrogens delay the onset of the anagen phase must be avoided.
of the hair follicle cycle, and consequently, • In cases of secondary bacterial pyoderma,
Clinical Presentation follicles remain in telogen phase. They may proper topical antimicrobial treatment
DISEASE FORMS/SUBTYPES also terminate the anagen phase and induce (e.g., chlorhexidine shampoo, antibiotic
• Males: testicular tumors, especially Sertoli involution of hair follicle. cream, or systemic antibiotics) may be
cell tumors. In addition to symmetrical, required.
noninflammatory alopecia, often find femini- DIAGNOSIS
zation with signs of gynecomastia (enlarged PROGNOSIS & OUTCOME
nipples), pendulous penile sheath, absence Diagnostic Overview
of spermatogenesis, myelosuppression, and An acquired symmetrical, noninflammatory • Prognosis is generally excellent, but
unilateral enlarged testis. alopecia associated with gynecomastia and/or it is important to remember that some
• Intact females: polycystic ovaries or ovarian testicular abnormalities (particularly cryptor- clinical signs such as gynecomastia can be
tumors, generally originating from granu- chidism) strongly suggests hyperestrogenism. irreversible.
losa cells; in addition to the symmetrical, • Normal haircoat is typically restored within a
noninflammatory alopecia, gynecomastia, Differential Diagnosis few months after gonadectomy or withdrawal
cystic endometrial hyperplasia, leiomyomas, • Hypothyroidism of exogenous source of estrogen.
and irregular estrous cycles can be seen. • Hyperadrenocorticism • Metastatic Sertoli cell tumors are rare because
Prolonged estrus also can cause myelosup- • Recurrent flanks alopecia most of these tumors are benign. Risk of
pression (anemia, thrombocytopenia, and • Alopecia X metastases increases for larger (>2 cm in
leukopenia). • Other follicular dysplasias diameter) tumors.

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