Vaginitis in dogs: A simple approach to a complex condition - Veterinary Medicine
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Vaginitis in dogs: A simple approach to a complex condition
A definitive cause of vaginitis, which can range from anatomical abnormalities to systemic conditions, often cannot be determined. But this theriogenologist's clear diagnostic and treatment plan can help you eliminate the condition's irritating effects.


Vaginal bacterial culture

Table 1. Aerobic Bacteria Isolated from Dogs with Vaginitis*
Any infectious component of vaginitis is considered to occur secondary to some underlying cause of inflammation since the bacteria most commonly cultured from dogs with vaginitis are the normal flora in the vagina, which originate on the skin and from the rectum (Table 1).3-6 Because the vagina is not sterile, interpret culture results with caution and have the laboratory quantify bacterial growth. A significant culture result is moderate to heavy (3+ to 4+) growth of one or two bacterial species. Collect culture samples with a long, guarded instrument, if possible.7 Aerobic bacterial culture is sufficient because Mycoplasma and Ureaplasma species have not been cultured more commonly from dogs with vaginitis than from dogs with no history of reproductive tract disease, and fungal vaginitis in dogs is rare in North America.8,9

Urinalysis and bacterial culture

UTIs and vaginitis are often concurrent.2 UTIs are frequently caused by bacteria ascending from the distal urethra and surrounding area.10 It is easy to see how vaginal flora overgrowth could cause UTIs and, conversely, how infected urine passing through the vagina could cause vaginitis.11 Diagnosing a UTI requires collecting urine directly from the urinary tract since free-catch samples will be contaminated with vaginal contents. Collecting urine by cystocentesis for urinalysis and aerobic bacterial culture is recommended.

Digital vaginal examination

It is important to perform a digital vaginal examination in all dogs with clinical signs of vaginitis. Vaginal anatomical anomalies (described below) are a common underlying problem in dogs with adult-onset vaginitis. Vaginal strictures or septa can be detected by digital vaginal examination in 88% of cases.12,13


Vaginoscopy can help you diagnose vaginal anatomical anomalies and assess the degree of erythema of the vaginal mucosa. While vaginoscopes are marketed for dogs, their length and the diameter of their viewing orifices are similar to that of large otoscope cones. Thus, a large otoscope cone is adequate for vaginoscopy, revealing vaginal anomalies visible with a vaginoscope in 96% of cases.12,13

Vaginal anomalies described in dogs include

  • Strictures, or stenoses, which are circumferential narrowings of the vaginal vault. Theses narrowings are most commonly found just cranial to the urethral papilla.
  • Vaginal septa, which are pillars or walls of tissue within the vagina.

Both these anomalies result either from abnormal dissolution of the appropriate portions of the paired paramesonephric (müllerian) ducts or abnormal joining of the paramesonephric ducts with the caudal urogenital sinus.

The incidence of vaginal anomalies in dogs has not been reported. Anecdotal evidence suggests that many dogs with vaginal anomalies do not have genitourinary disease. One study attempted to create an objective measure of the degree of stricture based on measurements of the vagina and vestibule from vaginograms.14 This study did not specifically address dogs with vaginitis but did, in general, show that dogs with severe vaginal strictures and associated disease of the genitourinary tract had a poor response to any treatment modality.14

The vaginal mucosa should be the same rosy-pink color as healthy oral mucous membranes. While vaginitis cannot be diagnosed without evidence of vaginal inflammation, be aware that some diagnostic tests (e.g. vaginal swab, vaginoscopy) readily cause vaginal erythema and that some dogs have markedly erythematous vaginal mucosa with no other evidence of vaginitis. In a survey of eight dogs, four of which were control dogs and four of which had clinical vaginitis, two of the normal dogs had mild to moderate erythema of the vaginal mucosa. Three of the eight dogs developed erythema secondary to diagnostic testing.15


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