Periovulatory changes in the endoscopic appearance of the reproductive tract and teasing behavior in the bitch

A variety of diagnostic techniques have been applied to address the problem of determining optimal mating time in the bitch, although some have not been objectively investigated. Nine healthy bitches were examined daily using routine clinical methods as part of their normal breeding management with the aim of establishing which method was most useful. Accordingly, measurement of the degree of vulval swelling, endoscopic measurement of the vaginal mucosal color and appearance, and objective evaluation of behavior of the bitch were related to the time of ovulation (calculated when progesterone reached 5 ng/mL; Day 0) and the duration of the fertilization period (Day 2 to Day 5) determined by measurement of plasma progesterone concentration and assessment of vaginal cytology. There was a surprisingly large individual variation in measurements of vulval swelling, such that although trends were apparent this technique was not precise enough to establish the optimal mating time. However, measuring color saturation and vaginal mucosal fold width was successful. A consistent change in the mucosal color saturation was observed that related to the beginning (Day -5) and duration of the fertile period although there was no difference in measurement of color saturation between Day -5 and Day 2 (P = 0.31), and Day 2 and Day 5 (P = 0.43). The vaginal mucosal folds were smaller in width at the beginning of the fertilization period (Day 2) than at the beginning of the fertile period (Day -5) (P = 0.008), and all bitches had a consistent appearance of mucosal contours on Day 3. Assessment of sexual behavior was not considered precise enough to enable determination of the optimal time for mating because of the large amount of individual variation in behavioral scores. There was no difference in female behavior scores between Day -5 and Day 2 (P = 0.29), or between Day 2 and Day 5 (P = 0.06). Using objective techniques this study has quantified changes in the color and fold width of the vaginal mucosa that have previously only been subjectively reported. These changes can be used to identify the fertilization period and it is possible, with future refining of the technique, that endoscopic examination could replace vaginal cytology to be used in conjunction with plasma progesterone concentration when examining bitches to determine the optimal time to breed.