Vaginal and uterine microflora of adult dogs

Aerobic and anaerobic microflora were identified and quantitated in 82 vaginal and 78 uterine samples obtained from mature bitches during different stages of the estrous cycle. The mean +/- SD of total bacterial counts/100 mg of vaginal contents of the 82 bitches was log 5.0 +/- 1.5, ranging from log 2.4 to log 8.8. The count at the estrous stage (log 7.8 +/- 0.7) was significantly higher (P less than 0.05) than that at the anestrus (log 4.4 +/- 1.0), pregnancy (log 5.9 +/- 1.3), and postpartum (log 5.1 +/- 1.5) stages. The common organisms isolated from the vaginas were Bacteroidaceae, streptococci, Pasteurella spp, and mycoplasmas. Organisms were isolated from 48 (68%) of 78 uterine samples. The range of total counts/100 mg of uterine contents was from log 1.6 to log 8.3. Staphylococci and mycoplasmas were frequently isolated from the uterine contents. Although many uterine microfloras were similar to vaginal microfloras, some uterine culture had a single isolate identified. There were no pathologic findings in most of the uteri. Seemingly, vaginal bacteria frequently flow into the uterus, yet they rarely cause uterine infection.