The importance of the diestrus stages (early, middle, late) to the diagnosis of the endometrial disease in the bitch

Abstract

The endometrium is the uterine layer wherein embryo implantation and development take place. Complete knowledge of the endometrium’s normal histology is critical for advancing the diagnosis of subclinical endometrial diseases. Several researchers studied subclinical endometritis (END) in different species, but the cause/s remains unknown. Furthermore, simple and reliable diagnostic tools are still necessary to diagnose subclinical END. In the bitch (Canis lupus familiaris), diestrus has been selected as the stage of the reproductive cycle to perform the diagnosis of END. This work aimed to perform morphometric and cytological studies in bitches with normal endometrium (NE) and END in diestrus’ stages. Forty-five mixed-breed clinically healthy bitches, in diestrus were used in this study. Biopsies and cytology were obtained from uterine horns, processed, and examined using a microscope. Samples from NE and END were selected, images acquired, and software for image analysis was used to measure the endometrial thickness (ET), external glandular diameter (EGD), internal glandular diameter (IGD), glandular density, and glandular cell height (CG). Significant differences were observed in GC height, EGD, IGD, and serum progesterone (P4) concentrations along diestrus. In END, both EGD and IGD were smaller than NE. The current study showed histomorphometric characteristics that appear to be influenced by P4 concentrations. In our opinion, it is relevant to consider how far the bitch had progressed into diestrus at the moment of the diagnosis of endometrial disease. Data recorded in the present study could be helpful to clarify cases of bitches with unexplained infertility or subfertility.