Induction of Parturition with Aglepristone in Various Sized Bitches of Different Breeds

Evaluation of aglepristone and oxytocin on induction of parturition in guinea pig

BACKGROUND

Induction of parturition in guinea pigs appears to be essential because these animals have a higher rate of reproductive problems than rabbits and small rodents.

OBJECTIVES

Since aglepristone (AGL) is a competitive progesterone antagonist acting through binding to progesterone receptors while oxytocin (OT) is a powerful constituent of uterine smooth muscle, the aim of this study was to evaluate the clinical and ultrasonographic impacts of AGL and OT on guinea pig parturition induction.

METHODS

In this study, guinea pigs were allocated into five groups; each included five animals on the 61st day of pregnancy. In the aglepristone group (Agle), AGL was administrated subcutaneously (SC) once daily on 2 consecutive days (Days 61 and 62 post mating). Oxytocin (OT) was administered subcutaneously once and twice at 4-h intervals on Day 62 post mating in oxytocin 1 (Oxy1) and oxytocin 2 (Oxy2) groups, respectively. The animals in the aglepristone-oxytocin group (Agle-Oxy) received AGL subcutaneously once daily on 2 consecutive days (Days 61 and 62 post mating) and OT on Day 62 post mating. The remaining sows received saline solution (0.9% NaCl) in the control group.

RESULTS

According to the results, fetal heart rate, temperature, neonatal and maternal survival rates were not significantly different between the treatment and control groups (p > 0.05). Biparietal diameter of head and body weight of neonates in the Agle, Oxy2 and Agle-Oxy groups showed a significant decline, compared to the control group (p < 0.05). The time interval between injection and delivery and the duration of pregnancy was significantly reduced in Agle, Oxy2, Agl-Oxy groups, compared to the control and Oxy1 groups.

CONCLUSIONS

In conclusion, it seems that treatment Oxy2 can induce parturition in guinea pigs without side effects and lower pain during induction of parturition.

Case Report: Medical Management of Prolonged Gestation of a Mummified Fetus in a Bitch

A 3-year-old female rough coated collie was presented at day 69 (D69) after the first mating. She was mated on 2 consecutive days based on ovulation timing by the referring veterinarian. At day 30 post breeding, a single, live embryo was seen on ultrasound by this veterinarian. On D69, the bitch was presented to us because she lacked signs of impending parturition such as vulvar discharge or nest building behavior. On general examination, the bitch appeared clinically healthy and no prodromi were present. On abdominal palpation a small, firm structure and a slightly enlarged uterus were detected. There was no vulvar discharge. Using vaginoscopy we could not see any signs of cervical dilatation. Additionally, ultrasonography revealed the presence of a collapsed fetus in the uterus with a moderate amount of echogenic fluid surrounding it and the plasma progesterone concentration was 2.6 ng/ml. A parturition induction protocol was initiated: a progesterone receptor antagonist was administered, followed by PGF2α to induce cervical relaxation and uterine contractions. The fetus was expelled 3 days later, without noticeable damage to the reproductive tract of the dam. The bitch subsequently delivered two more litters without complications. To our knowledge this is the first clinical report that demonstrates a successful non-surgical treatment to expel a mummified fetus after prolonged gestation. The pharmacological treatment did not affect the future fertility of the breeding dog, which is an important outcome for breeders.

Towards scheduled pre-parturient caesarean sections in bitches

Elective caesarean section (CS) is the safest means of delivering the litter in bitches in specific situations. Timeously performing elective pre-parturient CSs at a fixed time would be convenient and prevent emergency CSs and foetal demise. This review proposes a method of performing elective pre-parturient CSs which is safe for both the bitch and puppies. Brachycephaly, small litters and large litters, preceding litter delivered by CS and trial of labour after a preceding CS are identified as factors increasing the need for CS whereas emergency CS is identified as factor increasing foetal demise. The first day of cytological dioestrus more precisely predicts the day of onset of spontaneous parturition than the first day of the LH surge or the dates during oestrus on which progesterone (P4) first exceeds 6 nM or 16 nM. Foetal biparietal diameter at the time of onset of spontaneous parturition varies too much to accurately predict readiness for CS. During the last few days of gestation, P4 with cut-off concentrations at 15.8, 8.7 and 3.18 nM, but not plasma cortisol concentrations, hold promise as predictors of onset of parturition and when to perform pre-parturient CSs. A protocol associating medetomidine hydrochloride as premedicant with propofol as induction agent and sevoflurane as maintenance is safe for scheduled CS and yields good maternal and puppy survival rates at delivery, 2 hr and 7 days after CSs. Clinicians have to pay attention to the haematocrit of bitches at the time of cervical dilatation which is at the lower end of the normal reference ranges for non-pregnant dogs and to the decline in haematocrit during CS (as a proxy for blood loss) which is approximately 7% for both parturient (open cervix) and pre-parturient (closed cervix) CSs. Pre-parturient CSs can be scheduled and performed 57 days after onset of cytological dioestrus with puppy survival rates of 99%. Collectively, these studies provide a protocol to safely perform elective CSs in a large proportion of the obstetric population at a convenient time of the day but more research is required with larger numbers to establish whether this practice is routinely safe and safe in all breeds.

Neonatal puppy survival after planned caesarean section in the bitch using aglepristone as a primer: A retrospective study on 74 cases

Since most of dystocia end up in caesarean sections (C-sections), the history of any problem during whelping is a good reason to plan in advance a further C-section. Our aim was to confirm that on a large sample and over an extended period of time, mortality in puppies <2 weeks of age was low, born after a planned C-section using aglepristone as a primer. Seventy-four C-sections on 59 different bitches were included. Bitches were monitored during oestrus to estimate the day of ovulation by progesterone assays; 60, 61 or 62 days after ovulation, foetal viability was checked by ultrasonography and progesterone plasma level was measured. None of the bitches was at term (progesterone plasma level >2 ng/ml). An injection of aglepristone was performed in late afternoon to block the effect of progesterone, mimicking its drop at the end of pregnancy. The C-section was conducted the following morning. Twenty-one breeds were represented most of which were bulldogs (26%, 21/74) and Great Danes (16%, 13/74). Four hundred and thirty-five puppies were born. A total of 43/435 puppies died within the first 2 weeks (9.89%). None of the puppies showed any external signs of prematurity. The average number of deaths per litter relative to the date after ovulation was similar (0.5 pups per litter at day 60, 0.7 at day 61, 0.4 at day 62). This study shows that planned C-section after an accurate determination of ovulation and using aglepristone as a primer is a safe procedure for bitches and their offspring. It may be offered to owners if a pregnant bitch is "at risk" of dystocia.

Curtailing parturition observation and performing preparturient cesarean section in bitches

Properly planned elective cesarean section (CS) in bitches is considered safe and justified for some breeds. Therefore, planning a scheduled (fixed date and time) preparturient CS in bitches belonging to a subpopulation where a CS is unavoidable, seems justified. The first day of cytological diestrus (D0) was used to predict the date of parturition. The aims of this study were to (1) compare the mortality of puppies delivered by preparturient CS to those delivered by parturient CS, (2) determine the extent to which a preparturient CS (performed at 08:00 on D57, while the cervix is closed) would shorten gestation, (3) compare the level of progesterone at the time of preparturient CS to that at the time of parturient CS, (4) compare the change in hematocrit before and after CS for parturient- and preparturient CSs. Out of 99 gestations for which D0 was known and a preparturient CS planned, the CS was performed at the scheduled time in 61%, before the scheduled time because cervical dilatation had started in 32% and before the scheduled time in 7% because the bitches had started showing signs of impending parturition, although their cervices were still closed. This study showed high neonatal survival ratios and good Apgar scores after preparturient CS with 99% of puppies delivered by preparturient CS born alive and 98.8% surviving to 2 h. Performing preparturient CSs shortened gestation by four to 52 h. Progesterone level was significantly higher at the time of preparturient CSs than at the time of parturient CSs. Further studies are required to determine whether preparturient CSs on D57 are routinely safe in all breeds, does not affect long term survival of the puppies and to timeously identify bitches in which parturition starts prior to the date and time for the scheduled elective preparturient CS.

Puppy survival and vigor associated with the use of low dose medetomidine premedication, propofol induction and maintenance of anesthesia using sevoflurane gas-inhalation for cesarean section in the bitch

The safety of an anesthetic protocol consisting of medetomidine hydrochloride (7 μg/kg iv) as premedicant, propofol, (1-2 mg/kg iv) as induction agent and sevoflurane, at 2% in oxygen for maintenance of anesthesia was studied in 292 cesarean sections (CSs) and 2232 puppies delivered. Medetomidine effects were reversed using atipamezole hydrochloride at 50 μg/puppy sc immediately following delivery and in the bitch iv immediately following surgery. The protocol's safety for puppies was expressed using survival immediately, 2 h and 7 d after delivery, and Apgar scores (measurement starting 15 min after delivery of the last puppy). The maternal survival rate was established immediately, 2 h and 7 d after cesarean section (CS). The CSs included 148 on Boerboel, 84 on English bulldog and 60 on other purebred bitches, which resulted in 1378, 541 and 313 puppies, respectively. Boerboel, English bulldog and other purebred bitches yielded 97.39%, 96.67% and 91.69% live puppies at delivery, 95.43%, 88.35% and 89.78% alive by 2 h and 89.19%, 79.11% and 84.03% alive by 7 d. Sixteen (1.16%), 32 (5.59%) and 4 (1.28%) malformed Boerboel, English bulldog and other purebred puppies were euthanized. Thirty five, 18 and 26, Boerboel, English bulldog and other purebred puppies were stillborn respectively, of which 12, 9 and 15, respectively had been discovered dead upon ultrasound examination immediately before CS. After correction for fetuses found dead on ultrasound examination and malformed euthanized puppies, 98.21%, 95.60% and 94.30% of Boerboel, English bulldog and other purebred puppies survived until 2 h and 91.78%, 87.17% and 88.26% until 7 d. Two-hour survival rates are negatively correlated to the proportion of puppies in a litter with scores of 8 or below (r = 0.14, P = 0.01, n = 292 litters) and tends to be positively correlated to the lowest Apgar score in a litter (r = 0.11, P = 0.05, n = 292 litters). This study shows that medetomidine hydrochloride in the protocol used is a safe premedicant in bitches prior to cesarean section and is associated with good puppy vigor as well as 2 h and 7 d puppy survival rates. The use of medetomidine as premedicant permitted use of less than half the dose of propofol usually required as induction agent.