Merck Manual

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Professional Version

Vaginitis in Small Animals


Mushtaq A. Memon

, BVSc, PhD, DACT, Department of Veterinary Clinical Sciences, Washington State University

Reviewed/Revised Nov 2013 | Modified Oct 2022

Inflammation of the vagina may occur in prepubertal or mature (intact or spayed) bitches. It is rare in queens. Vaginitis usually is due to bacterial infection, which may be secondary to conformational abnormalities such as vestibulovaginal strictures. Viral infection (eg, herpes), vaginal foreign bodies, neoplasia, hyperplasia of the vagina, androgenic steroids (eg, mibolerone), or intersex conditions also may cause vaginitis.

The most common clinical sign is a vulvar discharge. Licking of the vulva, attraction of males, and frequent micturition also may be seen. Signs of systemic illness are not present, and the hemogram and biochemical profile are normal. The absence of these abnormalities helps differentiate vaginitis from open-cervix pyometra, the most important differential diagnosis. The diagnostic evaluation should include a digital examination of the vagina, vaginoscopy, cytology, and if necessary, culture of the exudate, as well as abdominal radiographs or ultrasonography to evaluate the uterus. An anterior vaginal culture may be obtained using a guarded sterile culture swab. The vagina contains normal bacterial flora; therefore, culture results must be interpreted cautiously. A heavy growth, especially of one organism, is probably more significant than a light growth of several organisms.

Predisposing factors such as foreign material or anatomic abnormalities should be corrected. Bacterial infection may respond to local treatment (ie, vaginal douches). Systemic, broad-spectrum, bactericidal antibiotics may be needed for persistent infections. Prepubertal animals often do not require treatment, because the vaginitis nearly always resolves with the first estrus. Therefore, it may be wise to delay elective ovariohysterectomy in affected animals until after their first estrous cycle.

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