Endometrial thickness of bitches in different periods of diestrus

The phases of the canine estrous cycle are divided into anestrus, proestrus, estrus and diestrus and the bitch is considered nonseasonal monoestric. The dog has a very characteristic diestrus phase that is longer than other animals, lasting 55-75 days. The diestrus phase is characterized in bitch for increasing of P4 in the first middle and E2 fluctuations in the second middle of the phase with a peak of P4 between days 15 to 25 post ovulation (P.O.) and peak of E2 around day 40. During the estrous cycle, the endometrium of bitch undergoes morphological and biochemical changes that are associated with the proliferation, apoptosis and cell differentiation. The objective of this study was to determine the thickness of the endometrium in diestrus phase of bitches on specific days 10, 20, 30, 40, 50 and 60 P.O. Right and left uterine horns of 26 clinically healthy dogs of different ages and with no defined breed were analyzed histologically. The experiment was approved by the Ethics Committee on the use Animals (CEUA), number 1863. The dogs underwent ovariohysterectomy (OSH) to 10 (n = 10), 20 (n = 8), 30 (n = 8), 40 (n= 8), 50 (n = 8) and 60 days (n = 10) P.O. Hematoxylin-eosin staining was performed on slides and subsequently the slides were photographed by a camera attached to the optical microscope objective of 4x. The evaluation were made in 20 endometrial thickness per slide and it was measured by using the software MOTIC Imageplus 2.0®. All parameters were assessed for normality assumption Shapiro-Wilk, considering normal data when P> 0.01. The samples were subjected to ANOVA followed by Tukey test (P <0.05). The mean thickness of the endometrium from the uterine horns was: 10 days = 1017.98 μm; 20 days = 1237.8 μm; 30 days = 1137.54 μm; 40 days = 1179.19 μm; 50 days = 1048.52 μm; and 60 days = 1222.01 μm. No differences were found statistics in endometrial thickness at different times of the diestrus, 10, 20, 30, 40, 50 and 60 days after ovulation. The conclusion is that endometrial thickness of bitches did not differ between the post-ovulation days.