Ovarian and uterine changes during the oestrous cycle in female dogs.

CONTEXT: An accurate staging of sexual cycle is essential for the optimum timing of medical interventions. AIMS: Here, an updated insight into clinical, endocrinological and vagino-cytological parameters, and their correlation with histomorphology of ovarian and uterine tissue samples is presented. METHODS: Samples from 39 dogs were collected at various stages of the oestrous cycle: pro-oestrus (n =8), oestrus (n =12), dioestrus (n =9) (luteal phase) and anoestrus (n =10), according to clinical observations. Final allocation of samples was done after histomorphological evaluation of all tissues. Peripheral oestradiol-17ß (E2) and progesterone (P4) concentrations were measured, P4 by both chemiluminescent immunoassay (CLIA) and radioimmunoassay (RIA). KEY RESULTS: Differences were observed between determination of the stage of the oestrous cycle, either by clinical, endocrinological or histomorphological evaluation. Individuals considered to be in clinical and endocrinological oestrus, had entered the luteal phase according to histomorphology. P4 concentrations measured by two different assays differed, underlying the importance to understand that absolute P4 concentrations may deviate depending on the used assay. Comparison of E2 and P4 concentrations is suggested to be useful when defining the transition from early follicular phase to the time of ovulation. CONCLUSIONS AND IMPLICATIONS: Based on parallel histomorphological observations, combined with clinical and endocrinological findings on the same individuals, the present study emphasises that an accurate classification of the stage of the cycle in female dogs based solely on clinical and endocrinological assessments can be difficult. The histomorphological findings presented herein provide new insights into the transitional phases between the different stages of the oestrous cycle in the dog.

Expression of uterine oxytocin receptors and blood progesterone, 13,14-dihydro-15-Keto-Prostaglandin F2α, and ionized calcium levels in dystocic bitches.

This study aimed to examine the etiology of canine dystocia by measuring the relative expression of oxytocin receptor (OXTR) mRNA and the concentration of serum progesterone, plasma PGF2α metabolite (PGFM), and blood ionized calcium (iCa) near term and in dystocia. Altogether 58 bitches were included in this study, 41 of which underwent cesarean section (CS). The four CS groups were based on history: complete uterine inertia (CUI; n = 7), partial uterine inertia (PUI; n = 13), obstructive dystocia (OD; n = 10), and elective cesarean section (ECS; n = 11). An additional group of medically treated dystocia without CS (MD; n = 8) and a control group (C; n = 9) with normal parturition (without CS and medical treatment) were also formed. Blood samples were taken prior to CS or medical treatment. Progesterone concentrations were highest in the ECS and a significant difference (p < 0.05) was observed between the ECS and the OD and between the ECS and the combined dystocia (CUI, PUI, OD, MD) groups (COMB). Highest concentrations of PGFM was observed in the C, the difference being significant (p < 0.05) between the C and the ECS and between the C and the COMB group. The progesterone:PGFM ratio was significantly (p < 0.05) higher in the ECS than in the C and the COMB group. No significant difference (p > 0.05) was observed in iCa concentrations between the groups. Relative OXTR mRNA expression was evaluated with real-time PCR from full-thickness uterine samples taken from the incision site during CS. The expression was highest in the ECS and the difference in expression was significant (p < 0.05) between the ECS and the OD and between ECS and the combined dystocia (CUI, PUI, OD) groups (COMB2). The study supports previous reports of decreasing progesterone and increasing PGFM during prepartum luteolysis. Upregulation of OXTR occurs near term. In obstructive dystocia, a prolonged influence of oxytocin and uterine exhaustion may lead to downregulation of OXTR. Complete primary uterine inertia may have a different etiology as no clear decrease in OXTR was observed in CUI as in OD. It remains unclear if parturition ceases because of uterine inertia or if uterine inertia occurs because of ceased parturition and desensitization of receptors.

Effect of insemination with doses of 2 or 15 million frozen-thawed spermatozoa and semen deposition site on pregnancy rate in dairy cows.

The effects of low-dose artificial insemination (AI) on pregnancy rates have seldom been studied in lactating dairy cows. We evaluated the pregnancy results after AI with doses of 2 and 15 million frozen-thawed spermatozoa and the effect of semen deposition in lactating dairy cows. A total of 284 first inseminations with 2 million spermatozoa and 312 first inseminations with 15 million spermatozoa were performed on 480 dairy farms. Low-dose inseminations (2 million spermatozoa) under field conditions in commercial dairy herds, without estrus synchronization, generally resulted in significantly reduced pregnancy rates compared with normal doses (15 million spermatozoa). The bull x technician effect on fertility was statistically significant. This finding indicates that there is a high variability in fertility among bulls using 2 million spermatozoa per dose. The semen deposition site did not influence pregnancy rates. It is concluded that a dose of 2 million frozen-thawed spermatozoa is probably too low for most bulls to achieve acceptable pregnancy rates in dairy cows.