Determination of optimal time for mating by artificial insemination with chilled semen using luteinizing hormone surge as an indicator in beagles

Progesterone Analysis in Canine Breeding Management

Progesterone is a worthwhile addition to the clinical assessment of cycle stage for breeding, elective cesarian delivery, and reproductive management in the bitch if reliably measured. Clinical decisions based on systemic progesterone concentrations also require the rapid return of results. Most commercially accessible analyses capable of returning results within a day still rely primarily on immunoassays of one kind or another. Point-of-care instruments utilizing similar technology have been developed more recently to enable results to be generated in-house. Repeated monitoring of progesterone on whatever platform can be useful if consistent collection and analysis protocols ensure acceptable precision, accuracy, and repeatability.

Metformin alleviates the dysregulated testicular steroidogenesis and spermatogenesis induced by carbimazole in levothyroxine-primed rats

Most of the published experiments about carbimazole (CMZ)-induced testicular injury are constructed in normal healthy animals, which lakes the translational identification. Despite metformin (MET) having advantageous effects on injured testicles, its impact on thyroid function is arguable. In the current levothyroxine (LT4)/CMZ model, Wistar rats were primed by LT4 for sixty days. CMZ was then given individually or simultaneously with different doses of MET, 100, 200, and 400 mg, daily for thirty days. Serum was assessed for thyroid profile panel, sex hormones, and gonadotropin levels. Testicular tissues were examined for steroidogenesis, spermatogenesis, inflammation, and apoptosis. Histopathology of thyroid and testes were examined, besides thyroidal nuclear factor (NF)-kB expression. MET in a dose-response manner improved the LT4/CMZ-induced testicular toxicity by increasing the steroidogenic acute regulatory protein (StAR), and 17-β-hydroxysteroid dehydrogenase (17βHSD) activities, the proliferating cell nuclear antigen (PCNA), sperm count and motility, sex hormones, and gonadotropin levels. MET-400 mg markedly decreased the elevated NF-kB expressions, tumour necrosis factor (TNF)-α, caspase-3, and BAX, and increased BCL-2. LT4/CMZ could be used as translational animal modelling. MET displayed a dose-dependent ameliorative effect on the LT4/CMZ model without significant harmful effects on thyroid functions. MET-testicular protective roles in diabetics with thyroidal diseases should be explored.

Ultrasonographic observation in combination with progesterone monitoring for detection of ovulation in Labrador Retrievers

Although it is well known that the ovulation occurs during a period of time after LH surge in dogs, there are few reports of observing the entire process of development, ovulation and luteinization of each follicle. This study aimed to detect the ovulation kinetics by ultrasonography in combination with progesterone monitoring and therefore identify the time-range of the ovulation process in a dog. Daily transabdominal ultrasonography and progesterone monitoring were conducted for 24 natural oestrus cycles of Labrador Retrievers. Ovarian follicles were observed as anechoic structure with contours before ovulation. Ovulation (follicular collapse) was defined as when follicles became cloudy and contours obscure by transabdominal ultrasonography. Ultrasound imaging was capable of identifying the day of ovulation for 94.7% (178/188) of the follicles through the appearance of collapsed follicle or corpus luteum. Ovulation was observed between LH 0 (the day of LH surge) and LH 5, with 48.0%, 33.5% and 15.0% for LH 2, LH 3 and LH 1, respectively. The total number of ovulations on LH 2 and LH 3 accounted for 81.5% (141/173) of the total ovulation in 24 cycles examined. Ovulation occurred in 12 cycles for 2 d and for 3 d in 12 cycles. Seventeen cycles (70.8%) with multiple days of ovulation showed the largest number of ovulations on LH 2. The average follicle diameter 3 d before the LH surge was less than 5 mm, then exceeded 5 mm 2 d before the LH surge. The average follicle diameter at the time of ovulation (follicular collapse) was 6.1 ± 1.0 mm (n = 118). On the day before ovulation, the average diameters of the follicles ovulated on LH 1, LH 2 and LH 3 were 5.0 ± 0.7 mm, 5.8 ± 1.2 mm and 6.2 ± 1.3 mm, respectively. There was a significant difference in the follicle diameter between LH1 and LH2 (p < .001), LH2 and LH3 (p < .05), and LH1 and LH3 (p < .001). Suggesting that it is difficult to estimate the ovulation day based on follicle size. This study showed that combination of ultrasonography with progesterone monitoring could follow follicular development, ovulation and luteinization of the ovary in Labrador Retrievers. The direct visualization of the ovulation was achieved in a non-invasive, labour-friendly way. Furthermore, the time-range of the ovulation process was clarified in a dog. These results may contribute to an accurate understanding of the optimum timing of mating and improved breeding efficiency, including artificial insemination and embryo transfer for Labrador Retrievers.

Comparison of progesterone assay by chemiluminescence or radioimmunoassay for clinical decision-making in canine reproduction

The Coat-A-Count® radioimmunoassay has been long and widely used to determine the concentration of progesterone in serum or plasma of bitches (progRIA), but was discontinued in 2014. The Immulite® 1000 LKPG1 chemiluminescence immunoassay has gained prominence since 2003 to determine the concentration of progesterone in serum of bitches, but the assay changed in 2012 (Immulite® 1000 LKPW1). This study assessed the feasibility of using Immulite® 1000 LKPW1 (progImm) to estimate the time of clinically relevant events during oestrus and compared progRIA and progImm 2 and 3 days after the first or only day of the luteinizing hormone surge (LH1). ProgImm first exceeded 5.1 nmol/L on the same day that progRIA first exceeded 6 nmol/L, a proxy for the occurrence of the LH surge, or the day before in 28 of 31 (90%) of oestrous periods. ProgImm first exceeded 13.6 nmol/L on the same day that progRIA first exceeded 16 nmol/L (a proxy for the day of ovulation) or the day before in 34 of 35 (97%) oestrous periods. ProgImm first exceeded 5.4 nmol/L on LH1 or the day before in 24 of 25 (95%) of oestrous periods. The median of progImm 2 days after LH1 was 1.2 nmol/L lower than the 10.7 nmol/L of progRIA (p = 0.001). The mean of progImm 3 days after LH1 was 2.2 nmol/L lower than the 19.0 nmol/L of progRIA (p < 0.001). In conclusion, the days on which progImm first exceeded 5.1 nmol/L, 13.6 nmol/L and 5.4 nmol/L effectively estimate the days on which progRIA reached 6 nmol/L or 16 nmol/L or LH1.

Normal progesterone profiles during estrus in the bitch: A prospective analysis of 1420 estrous cycles

Appropriate timing of insemination in the bitch, through monitoring of serial serum progesterone concentrations, has historically been based on the detection of important physiological reproductive events which include the LH surge and ovulation 2-3 days later. Previous hormone profile studies during the estrus period in the bitch, in which determination of these physiological reproductive events has been defined, have been based on low numbers of bitches of similar breeds and body weights. Therefore, the aim of this large-scale prospective study was to define the normal serum progesterone profile during the estrus period in a large number of bitches of various breeds and body weights. In addition, we investigated if the rate of change in progesterone concentrations during the fertile period affected the reproductive performance of bitches after insemination with either fresh or frozen-thawed semen. A total of 1300 individual bitches, representing 84 different breeds, contributed 1420 estrous cycles and 4213 serum progesterone values over the 11-year (2007-2017) study period. The mean (±SD) progesterone concentration at estimated LH0 was 2.7 ± 0.6 ng/ml and at the time of estimated ovulation it was 4.8 ± 0.9 ng/ml and 7.2 ± 1.3 ng/ml (LH+2 and LH+3 respectively). There was no difference in the shape of progesterone profiles for bitches of different body weights. Furthermore, mean progesterone concentrations on each day between LH-6 and LH+7 were not different amongst bitches of different breeds and body weights and there was no effect of mean progesterone concentrations on any day on whelping rate or litter size. However, there was a significant effect of the rate of change in progesterone concentrations on litter size when frozen semen was used. The litter sizes of bitches inseminated with frozen semen with slow progesterone curves were significantly smaller compared to bitches with fast progesterone curves (3.9 ± 1.8 vs 5.6 ± 3.1 pups per litter respectively; P < 0.001). There was no effect of bitch age on the normal progesterone curve, or its rate of change. This is the first report of the normal progesterone profile during estrus in the bitch derived from a large number of serial progesterone measurements obtained from bitches of various breeds and body weights. Importantly, the predictability and reliability of this progesterone profile regardless of breed or body weight gives clinicians the confidence to accurately determine the optimal time for insemination, which is critical to reproductive success, especially when frozen semen is used.

Individual fertility differences in the frozen-thawed spermatozoa among semen donors in the Labrador Retriever

Purpose

We aimed to validate and determine the possible application of transcervical insemination of frozen semen for improved breeding in guide dogs for the blind in Japan.

Methods

From February 2004 to March 2007, a total of 53 Labrador Retriever bitches, used for the breeding of guide dogs for the blind, were transcervically inseminated with frozen-thawed semen from 13 males by means of a cystoscope.

Results

The overall whelping and pregnancy rate with the frozen semen was 42%. Pregnancy rates ranged widely from 0 to 100% depending on the semen donor male. Of 13 males, 6 males exhibited severely poor fertility (less than 20% pregnancy rate) and 3 males exhibited high fertility (over 70% pregnancy rate) on artificial insemination. However, the spermatozoa motility after thawing was not significantly different among these dogs. In addition, heterospermic insemination revealed the optimal timing for transcervical insemination with frozen-thawed semen to be by day 6 after the LH surge.

Conclusions

Although transcervical insemination of frozen-thawed semen is effective for breeding of guide dogs for the blind, some modification of freeze-thawing procedures might be required to overcome individual fertility differences in the frozen-thawed spermatozoa among semen donor dogs,. In addition, the motility of spermatozoa after thawing might not be an appropriate indicator of the relative fertility of frozen-thawed spermatozoa in dogs.

The Prediction of Parturition Date in Canine Pregnancy

In bitches, the length of gestation is highly variable when measured from the day of mating, thus prediction of parturition may be greatly inaccurate when determined from this point. The ability to precisely predict the duration of pregnancy is of practical importance for managing parturition or planning caesarean section and this review analyses the methods that can be used to accurately forecast the day of parturition. At the time of breeding, determination of the luteinizing hormone surge and the initial rise in progesterone provide reliable information on gestational length of the bitch, but when pregnancy is ascertained, ultrasonography is the most useful tool to predict the delivery day. In fact, by ultrasonographic measurements of the extra-foetal and foetal structures an accurate prediction can be made both in early and late pregnancy.

Comparison of different methods used for oestrus examination in the bitch

The aim of this study was to determine the reliability of oestrus symptoms of the bitch (vulvar swelling, vaginal fluid, attraction of the male, teasing) and that of the most frequently used examination methods (vaginal smear, vaginoscopy, serum progesterone determination) which indicate the stage of the cycle and allow to predict the optimal day of mating (ODM). The determination of the cycle stage was based upon the number of days left from the day of examination to the day of parturition (DTP). Our results indicate that none of the above-mentioned symptoms and examination methods is reliable alone for the determination of DTP, and even the complex picture obtained from the integrated results of different methods will not enable an exact estimation. ODM can be predicted with a higher reliability, and 1-2 days before it, it can be detected very safely. Since most bitches are presented for timing to practitioners, a scheme was created based upon a scoring system, which gives a point value to each individual symptom and examination result, and judges the bitch according to the total amount of points.

Optimal Timing for Canine Artificial Insemination with Frozen Semen and Parentage Testing by Microsatellite Markers in Superfecundency

Parentage testing was performed in sixteen litters by canine artificial inseminations with frozen semen from different sires on Days 5 and 7 after the LH surge. It became apparent that only 25% of dams had superfecundation, but 43.8% of dams were whelped after insemination only on Day 5 after the LH surge and 31.3% of dams after insemination only on Day 7. Of the total 87 puppies, 46% were born after insemination on Day 5 after the LH surge and 54% after insemination on Day 7. This result strongly suggested that canine artificial insemination with frozen semen could be sufficiently successful also on Days 5 and 7 after the LH surge.