The outcome of twin pregnancies in mares

Brood-farm veterinarians were surveyed and theriogenology records were examined to obtain information on the natural outcome of rectally-diagnosed twin pregnancies. Four of the veterinarians estimated that 50% of mares with twin embryos had single foals. In the analyses of palpation records, 31 53 (58%) of the diagnosed twin pregnancies terminated in birth of one foal. However, the loss of one embryo without the loss of the other occurred significantly more often before day 40-42 (30 53 ; 57%) than after day 40-42 (1 16 ; 6%). Of the remaining 15 mares with diagnosed twins at day 40-42, 5 had two foals and 10 had no foals. The methods used for intervention when twins were diagnosed were unsatisfactory. Complete termination of pregnancy with a prostaglandin or an intrauterine flushing resulted in failure to reestablish a singleton pregnancy during the operational breeding season in 10 11 mares. Attempts to eliminate one embryo resulted in loss of both in 6 7 mares. The results indicated that, at the present time, nonintervention should be given more consideration as a method of handling twin pregnancies.     

Factors affecting pregnancy loss for single and twin pregnancies in a high-producing dairy herd

Our objective was to determine the magnitude of, and factors affecting, pregnancy loss for lactating Holstein cows on a commercial dairy farm when diagnosed with twin (n = 98) or single (n = 518) pregnancies using transrectal ultrasonography. Pregnancy losses were assessed with records of non-viable embryos at first pregnancy examination and embryo losses between the first (25-40 d after AI) and second (48 and 82 d after AI) post-breeding pregnancy examinations. Among cows diagnosed with single pregnancies, 3.7% were diagnosed with a non-viable embryo at first pregnancy examination, and 4.6% of those diagnosed with a viable embryo underwent pregnancy loss by the second examination. A total of 11.2% of cows diagnosed with twins experienced a single embryo reduction, whereas 13.3% lost both embryos. Overall, the total proportion of cows experiencing pregnancy loss or experiencing embryo reduction was greater for cows diagnosed with twin than single pregnancies (odds ratio; OR = 3.6), resulting in an embryo survival rate of 91.9% for cows diagnosed with single compared to 75.5% for cows diagnosed with twin pregnancies. Season of breeding and milk production were associated with pregnancy loss for single pregnancies, whereas CL number was associated negatively with embryo reduction and pregnancy loss for twin pregnancies. The risk of twinning and double ovulation among pregnant cows increased with days in milk (DIM), and the risk of double ovulation was greater for cows diagnosed with ovarian cysts and lacking a CL at initiation of an Ovsynch protocol. We concluded that in this herd, embryo reduction and pregnancy loss during early gestation was greater for lactating Holstein cows diagnosed with twin compared to single pregnancies. In addition, cows diagnosed with ovarian cysts and lacking a CL had an increased risk for double ovulation.     

Ultrasound determination of chorionicity in twin pregnancy: accuracy and operator experience.

To evaluate the accuracy of ultrasound in early detection of chorionicity and amnionicity in twin pregnancies and evaluate the role of operator-experience, a prospective follow up of 87 consecutive twin pregnancies was performed. Chorionicity and amnionicity were determined by 17 different observers, divided in 2 groups on the basis of their experience, using a composite of US markers at the first US examination confirming a viable intrauterine twin pregnancy. Accuracy of prediction was determined for both groups by comparison with postnatal pathology. From the 87 pregnancies examined at 10.1 (minimum 5.5 weeks, maximum 26.0) weeks of gestation, pathology was available in 82 cases and a correct prediction of chorionicity was made in all but two cases, both being diagnosed as monochorionic while dichorionic by observers belonging the more experienced group. No monochorionic pregnancy was missed and amnionicity was correctly diagnosed in all cases, including two monoamniotic twins. We conclude that use of a composite of ultrasound markers for early detection of chorionicity and amnionicity is reliable in a clinical setting where physicians with a variable degree of experience perform ultrasound examination.     

Induction of twinning in Holstein and Japanese black cows by ipsilateral frozen embryo transfer

Induction of twinning by ipsilateral nonsurgical transfer of two frozen-thawed Japanese Black bovine embryos to each of 20 Holstein and 26 Japanese Black cows, that had been kept under a stable in private farm conditions, was examined. The cows were monitored every 20 days from Day 25 to Day 65 of gestation for pregnancy and fetus survival (estrus is Day 0). Seventy-five per cent (15 of 20), 65.0% (13 of 20) or 60.0% (12 of 20) and 61.5% (16 of 26), 53.8% (14 of 26) or 50.0% (13 of 26) of Japanese Black cows were diagnosed pregnant at 25, 45 and 65 days after transfer by ultrasonic echography. Embryonic losses were observed between Days 25 and 65 in 29.2% (7) Holstein and 31.8% (7) Japanese Black cows. The twin pregnancy rate in Holstein and Japanese Black cows decreased with time; 60.0% (9 of 15) vs. 37.5% (6 of 16) at Day 25; 53.8% (7 of 13) vs. 28.6% (4 of 14) at Day 45 and 41.7% (5 of 12) vs. 15.4% (2 of 13) at Day 65. At calving, Holstein cows produced five sets of twins and seven single calves, and Japanese Black cows two sets of twins and 11 single calves. The twinning rate in Holstein cows was higher (P < 0.05) than that in Japanese Black cows, 41.7% (5 of 12) vs. 15.4% (2 of 13). The calf birth weight in Holsteins was heavier (P < 0.05) than that in Japanese Black dams (24.5 kg, 33.6 kg vs. 19.3 kg, 25.5 kg for twin and single calves). The placental weight in Holstein dams calving twins was heavier than that in Holstein dams calving a single calf or in Japanese Black dams calving either twins or a single calf (6.6 kg vs. 3.5 kg, 4.6 kg or 2.8 kg). The number of placentome in Holstein dams calving twins was also higher (P < 0.05) than that in Holstein dams calving a single calf or Japanese Black dams (103.5 vs. 41.8, 67.9, 33.0). The number of placentome was approximately double in dams calving twins than that of dams calving a single calf.     

Monoamniotic twins: what should be the optimal antenatal management?

Monoamniotic twinning is a rare event with an incidence of 1% of all monozygotic twins and associated with a high fetal morbidity and mortality. Confident early diagnosis is possible, but optimal management is not yet established. This article presents the experience of a single centre in managing all monoamniotic twins diagnosed during 1994-2000. Seven pairs of monoamniotic twins were identified for analysis. All were managed in accord with a unit protocol that involved early diagnosis, serial ultrasound examination and elective early delivery. In four cases, the detection of monoamnionicity was made during a first trimester nuchal scan. Discordance for structural abnormality was found in three cases where the co-twin was normal. Cord entanglement was detected antenatally in four cases. Two pairs of twins died before 20 weeks. One of these had early onset twin-twin transfusion syndrome. In five cases, the pregnancy continued beyond 20 weeks. A live birth rate of 90% and intact survival of 70% were achieved in this group. We believe that ultrasound is reliable in diagnosing monoamniotic twins and the detection of cord entanglement. Timing of elective delivery is a balance between the risks of preterm birth at a specific gestational age in an individual centre compared with the unquantifiable risks of fetal death if an expectant policy were pursued. The decision to deliver and at which gestational age should combine input from the parents, neonatologist, fetal medicine consultant and the obstetrician.     

Multi-fetal pregnancy reduction does not influence perinatal results in twin pregnancies.

The objective of this study was to compare perinatal results in multifetal pregnancies where the reduction to twins was performed with non-reduced twin pregnancies. Perinatal results in 99 sets of twins after transabdominal multifetal pregnancy reduction of triple and higher-order multiple pregnancies performed in a single center were compared with a control group consisting of 151 twin pregnancies conceived in the same time period after infertility treatment, which were not a result of reduction. The main outcome measures were length of pregnancies, weight of the newborns, percentage of miscarriages and the mode of the delivery were analyzed. No significant difference could be found at a 5% level of significance regarding the average duration of pregnancy or average weight of the twins. Fisher test on 5% significance level did not ascertain any significant difference in the probability of miscarriage between the group with reduction (5.26%) and the group without reduction (12.84%). At a 5% level of statistical significance, no significant difference in probability of perinatal death of the fetus or delivery of a stillborn fetus was found. The percentage of cesarean sections did not differ significantly in both groups. The analysis of both groups demonstrated that reduction of multifetal pregnancies to twins may not influence perinatal results in comparison to twin pregnancies where reduction was not performed.     

Photoperiod length and the estrus synchronization protocol used before AI affect the twin pregnancy rate in dairy cattle

This study addresses potential management risk factors affecting the incidence of twin pregnancies in high-producing dairy cows. Special attention was paid to the estrus synchronization protocol used before the AI resulting in pregnancy. Possible factors affecting the twin pregnancy rate were analyzed through binary logistic regression procedures on 2015 pregnant cows from July 2010 to July 2011. Twin pregnancy was recorded in 361 of the 2015 pregnancy diagnoses made (17.9%). Twin pregnancy rates differed among herds (P < 0.001) and ranged from 12.4% to 23.9%. Based on the odds ratios, the risk of twin pregnancy was reduced by factors of 0.65 or 0.71 when AI was performed during the warm season or an increasing photoperiod, respectively and increased by a factor of 1.11 for each unit increase in lactation number; by factors of 4.57 or 6.33 in cows that received a progesterone-releasing intravaginal device (PRID) plus 500 or 750 IU of equine chorionic gonadotropin (eCG) 28 days before the pregnancy AI, respectively; by a factor of 2.39 in cows with an ovarian cyst diagnosed in the 14 days prior to AI and treated with prostaglandins (PG); by factors of 1.94 or 3.91 in cows that received two PG doses during the 14 days prior to AI or cows that following failed PRID treatment had received PG started over the 28 days prior to AI, respectively; and by a factor of 2.58 in cows that had previously delivered twins compared to cows delivering singletons. Our results indicate that cow factors, such as lactation number and previous twining, as well as environmental factors, such as photoperiod and season and management related to synchronization protocols affect significantly the incidence of twin pregnancies.     

Spontaneous reduction of advanced twin embryos: its occurrence and clinical relevance in dairy cattle

Twin pregnancies represent a management problem in dairy cattle since the risk of pregnancy loss increases, and the profitability of the herd diminishes drastically as the frequency of twin births increases. The aim of this study was to monitor the development of 211 twin pregnancies in high producing dairy cows in order to determine the best time for an embryo reduction approach. Pregnancy was diagnosed by transrectal ultrasonography between 36 and 42 days after insemination. Animals were then subjected to weekly ultrasound examination until Day 90 of gestation or until pregnancy loss. Viability was determined by monitoring the embryonic/fetal heartbeat until Day 50 of pregnancy, and then by heartbeat or fetal movement detection. Eighty-six cows (40.8%) bore bilateral and 125 (59.2%) unilateral twin pregnancies. Embryo death was registered in one of the two embryos in 35 cows (16.6%), 33 of them at pregnancy diagnosis. Pregnancy loss occurred in 22 of these cows between 1 and 4 weeks later. Thus, 13 (6.2% of the total animals) cows, carrying one dead of the two embryos, maintained gestation. Total pregnancy loss before Day 90 of pregnancy (mean 69 +/- 14 days) was registered in 51 (24.2%) cows: 7 (8%) of bilateral pregnancies and 44 (35.2%) of unilateral pregnancies, and it was higher (P = 0.0001) for both right (32.4%, 24/74) and left (39.2%, 20/51) unilateral than for bilateral (8.1%, 7/86) twin pregnancies. The single embryo death rate was significantly (P = 0.02) lower for cows with bilateral twins (9.3%, 8/86) than for total cows with unilateral twins (21.6%, 27/125). By way of overall conclusion, embryo reduction can occur in dairy cattle, and the practical perspective remains that most embryonic mortality in twins (one of the two embryos) occurs around Days 35-40 of gestation, the period when pregnancy diagnosis is generally performed and when embryo reduction could be tried.     

Induction of twinning in crossbred heifers by ipsilateral frozen embryo transfer

Induction of twinning by means of nonsurgical ipsilateral transfer of two frozen embryos or of demi-embryos was attempted in 297 virgin crossbred dairy heifers that were kept at the following locations: in stables at our breeding station (Group 1), in a mountain field (Group 2) and at a private farm (Group 3). Of these, 187 heifers (63%) were diagnosed pregnant at 25 d after embryo transfer and 134 heifers (45%) were diagnosed pregnant at 60 d after transfer by ultrasonic echography or by palpation per rectum. At calving, 118 heifers produced 46 sets of twins and 72 single calves, for a total of 164 calves sixteen pregnant heifers aborted fetuses between 2 and 7 mo. The pregnancy rate of Group 1 (39%) was lower than that of Group 2 (48%) or Group 3 (50%). Abortion and mortality rates for Group 3 (8% and 8%, respectively) were significantly lower (P<0.05) than for Group 1 (16% and 12%) or Group 2 (13% and 18%). Twin calves had lower birth weights (P<0.05) than singles, but at 270 to 330 d of age, there was no significant difference between the weights of single and twin calves. Dystocia or difficult delivery was not observed heifers producing twins. Retention of the placenta was observed in twin calving heifers, with placenta retention levels the highest in Group 2 (33%) than followed by Group 1 (14%) and Group 3 (10%). When gestation periods were compared between single and twin calves in Groups 1 and 2, the gestation period of single calves was 5.0 to 7.0 d shorter than that of twin calves. No significant difference was observed between the gestation periods of single and twin births in Group 3.     

Screening for the small-for-dates fetus: a two-stage ultrasonic examination schedule.

To find an effective routine screening method for small-for-dates fetuses 474 women with singleton pregnancies participated in a two-stage ultrasonic examination schedule. At the first-stage examination, which was conducted in early pregnancy, fetal crown-rump length or biparietal diameter was measured for an accurate assessment of gestational age, which was essential for interpreting the results of the second-stage examination. The second-stage examination was performed at 34-36 weeks and entailed measuring seven fetal variables, the results of which were assessed singly and in combination after delivery to identify the best indicator of small-for-dates fetuses. Fetal head measurements proved to be the least sensitive indicators of growth retardation, correctly identifying only 56-59% of cases. Measurements of trunk area and circumference, however, correctly identified 81% and 83% of cases respectively, but the most effective screening index was the product of crown-rump length and trunk area: with this index 34 out of 36 small-for-dates fetuses (94%) were correctly identified. Calculating the product of crown-rump length and trunk area from ultrasonic displays is quick and simple, and combined with the first-stage examination is a highly reliable screening method for small-for-dates fetuses.     

Two examples of monoamniotic monozygotic twinning in diploid parthenogenetic mouse embryos

In experiments in which diploid parthenogenetic mouse embryos cultured entirely in vitro from the one-cell stage to the blastocyst were transferred to suitable recipients and maintained in "delay" for about 3 days before implanting, about 25-40% subsequently developed to somite-containing stages. In all, over 30 such embryos were examined. Most were morphologically normal, and equivalent to fertilized development observed on the 9th-11th days of pregnancy. A few embryos, however, had neural tube abnormalities, but of greatest interest were two sets of monoamniotic monozygotic twins. It is unclear whether the twins in some way resulted from the parthenogenetic condition, or from the "delayed" state. The present examples are discussed in the context of previous observations of monozygotic twinning in the mouse and man.     

Canadian Thalidomide Experience

Data are presented on 115 children, including three sets of twins, born in Canada in 1961 and 1962 with congenital malformations associated with the use of thalidomide by their mothers in early pregnancy. The epidemiological method is described. Of the 115 children, 74 were alive at the time of reporting, 41 of these being severely handicapped; 8 had been stillborn; 33 had died. Limb involvement was usually bilateral, affecting the upper limbs alone in 42 cases, and the upper and lower limbs in 41. Of 112 mothers, only 60 had had the drug prescribed by the physician providing maternity care; 87 were estimated to have first taken the drug before their last menstrual period or within 56 days thereafter. A plea is made for the development of better methods of collecting information on the occurrence of congenital malformations, with the aid of practising physicians.     

Improvement of in vitro fertilisation after treatment with buserelin,an agonist of luteinising hormone releasing hormone

Treatment with buserelin, an agonist of luteinising hormone releasing hormone, and human menopausal gonadotrophin was compared with the conventional treatment of clomiphene citrate and human menopausal gonadotrophin in the outcome of in vitro fertilisation. Seventy seven infertile women had 83 cycles of treatment with buserelin and human menopausal gonadotrophin, and concurrently another 328 infertile women were treated with clomiphene citrate and human menopausal gonadotrophin. Seven (8%) cycles were cancelled owing to inadequate superovulation or ovarian hyperstimulation in the women receiving buserelin and 103 (31%) were cancelled because of poor follicular development in those receiving clomiphene citrate. The mean number of oocytes recovered was significantly higher with buserelin (9·5 (SD 4·5) v 5·5 (2·2)) as was the mean number of embryos obtained (4·3 (2·4) v 2·9 (1·7)). Significantly more women who had an embryo transfer became clinically pregnant after treatment with buserelin (53% (30/57) v 30% (48/159), or 36% v 14% of treatment cycles). Altogether 33% (10) of pregnancies in women treated with buserelin were multiple compared with 23% (11) in those treated conventionally. Of the 17 completed pregnancies in women treated with buserelin, 11 resulted in the birth of live babies (eight singletons, two sets of twins, and one set of triplets) and six failed, five before 12 weeks'' gestation and one at 22 weeks. The 13 continuing pregnancies (32 weeks) were eight singletons, two sets of twins, and three sets of triplets. Of the 48 completed pregnancies in women treated with clomiphene citrate, 35 resulted in the birth of live babies (26 singletons, five sets of twins and four sets of triplets) and 13 failed, eleven before 12 weeks'' gestation and two by 27 weeks.Buserelin increased the chance of pregnancy after in vitro fertilisation compared with conventional treatment, but the risk of multiple pregnancy may be increased.     

The East Flanders Prospective Twin Survey (Belgium): a population-based register.

The East Flanders Prospective Twin Survey (EFPTS), started in 1964, is unique among the 17 major European twin registers because it is population based, the twins (and higher order births) are ascertained at birth, basic perinatal data are collected, chorion type is established and, when appropriate, genetic markers including DNA fingerprints, are determined. The total number of sets is 5089 twin, 158 triplet and 14 of higher order. Zygosity has been diagnosed on the basis of sex, placental structure and genetic markers in more than 95% of pairs. The EFPTS is the only large register that includes placental data and allows differentiation of three subtypes of monozygotic twins based on the time of the initial zygotic division: the dichorionic-diamnionic pairs (early), the monochorionic-diamnionic pairs (intermediate), and the monochorionic-monoamnionic pairs (late). Methodology and basic results in twins are considered in this article; detailed studies will be reported later. The sex proportion in dizygotic (DZ) twins is the same as in singletons, whereas monozygotic (MZ) twins number more girls than boys. The difference in perinatal mortality between DZ and MZ twins is limited to the monochorionic MZ subgroup. Birth weight is highest in DZ twins and diminishes stepwise in MZ dichorionic and MZ monochorionic twins. Duration of pregnancy follows the same trend but is limited to a few days. Iatrogenic pregnancies are increasing to the point of representing almost 50% of the twin births in 1997.     

High incidence of preterm births and early losses in pregnancy after in vitro fertilisation. Australian in vitro fertilisation collaborative group.

A fertilisation cohort of 244 pregnancies resulting from in vitro fertilisation was reported to a national register by eight units specialising in in vitro fertilisation. Early pregnancy losses were high, with 5% tubal ectopic pregnancies, 18% biochemical pregnancies, and an incidence of spontaneous abortion of 27%. Among pregnancies of at least 20 weeks'' gestation 22% were multiple, with 26 pairs of twins and four sets of triplets. The incidence of preterm births was more than three times higher than in the general population. Low birthweight rates were also higher, owing both to preterm births and to multiple pregnancies. The sex ratio and the incidence of major congenital malformations were similar to those in naturally conceived pregnancies. In this series the high fetal losses at all stages of pregnancy suggested maternal reproductive causes and should not be interpreted as being due to factors peculiar to in vitro fertilisation. Further analysis will be necessary when larger numbers are available.     

A study of the occurrence of monochorionic and monozygotic twinning in the pig

In humans as well as in most farm animals, monozygotic twins have been described. Nevertheless, only a few reports of twinning in the pig have been published. It has been suggested that monozygotic twins are formed during the first 14 days of pregnancy. This monozygotic twin study includes the investigation of porcine monochorionic embryos from 76 sows at days 26–29 post-insemination (p.i.), as well as an examination of 10 whole litters at days 21–22 p.i. In the former group, 29% of the sows carried monochorionic embryos. Based on DNA profiling using microsatellite markers, one monozygotic twin pair was found among these embryos. In the latter group, three monozygotic twin pairs were identified. Thus, it can be concluded that although the occurrence of monozygotic twins in pigs is a sporadic event, the fusion of extra-embryonic membranes is relatively common.     

Morphological study of the removed fetus after therapeutic abortion for echographic anomalies (apropos of 42 cases)

In 42 cases, fetal abnormalities were diagnosed by obstetric ultrasonography and the pregnancy was terminated. The malformations included: anencephaly (22), severe hydrocephaly (4, one with a spina bifida), encephalocele and meningocele (2) amniotic band syndrome (4; a correct prenatal diagnosis was performed during the second trimester in two cases), major anterior abdominal wall defects (2), Pena-Shokeir syndrome type I? (I), severe renal abnormalities (2), conjoined twins, dicephalus type (2), cystic hygroma and hydrops fetalis (2), osteogenesis imperfecta, type II (I). Thus, there were 23 fetuses with a polygenetically determined status; five fetuses could be affected by an autosomal recessive disorder.     

Observed and expected combined effects of clinical mastitis and low body condition on pregnancy loss in dairy cows

The objective was to compare the observed and expected combined effects of clinical mastitis before timed artificial insemination (TAI) and low body condition at 70 d postpartum (dpp) on pregnancy loss in dairy cows. Cows were examined for pregnancy by ultrasonographic examination 28-32 d after TAI; the presence of an embryo with a heartbeat was the criterion used to determine pregnancy. Cows diagnosed pregnant were re-examined by transrectal palpation of the uterus and its contents 28 d later to confirm pregnancy status and to identify pregnancy loss. Eighty-eight (17%) of 512 cows were diagnosed with pregnancy loss. Cows affected with clinical mastitis before insemination and a body condition score (BCS) ≤ 2.75 at 70 dpp were 2.03 times more likely to experience pregnancy loss, compared to cows without clinical mastitis and with a BCS > 2.75 (RR = 2.03; 95% CI = 1.15, 3.60; P = 0.01). This observed combined effect for pregnancy loss (RR = 2.03) was higher than the expected combined effect based on adding (RR = 1.39) or multiplying (RR = 1.42) absolute independent excesses due to clinical mastitis or low body condition.     

Pregnancy and the Nephrotic Syndrome

Nineteen patients with nephrotic syndrome, 13 with histological diagnosis, were studied throughout 31 pregnancies. Eight were diagnosed for the first time during pregnancy.Antenatal problems due to severe oedema, urinary tract infection, and refractory orthochromic anaemia were encountered. Eight patients were hypertensive at booking, and in two of these pregnancy was terminated; three others had a significant increase in blood pressure. In 12 of the remaining pregnancies a rise in blood pressure of 20 mm. Hg or more occurred towards term.There were 29 live births (including one set of twins), one stillbirth due to a cord accident, and one neonatal death. The infant birth weight, apart from being affected by hypertension, was related to the maternal serum albumin level.The patients have been under observation for up to 20 years. Fifteen have not shown any deterioration of renal function during the prolonged period of observation. One developed oliguric renal failure immediately post partum and three others died, two, four, and 12 years after their pregnancies.     

Hypoluteoidism in a bitch

Hypoluteoidism is characterized by insufficient secretion of progesterone by the corpora lutea during pregnancy. The resulting failure to maintain progesterone concentration above a critical level presumably could lead to fetal resorbtion as well as frank abortion. This report concerns a 2.5-year-old Bernese Mountain dog with a history of two previous pregnancies ending in abortion around Day 50 of pregnancy. The bitch was initially presented 2 days after mating. Physical and gynecological examination revealed no abnormalities. The infectious causes of abortion in the bitch, Brucella canis and herpesvirus, were excluded using serology. On Day 26 after mating, ultrasonography confirmed a pregnancy with at least four living fetuses. During the remaining part of the pregnancy repeated transabdominal ultrasonography and plasma progesterone measurements, using a RIA, were performed. On Day 42, ultrasonography revealed living fetuses but plasma progesterone concentration had decreased to 8.3 nmol/L, which is just above the threshold necessary to maintain a vital pregnancy. Oral treatment with 0.1mg medroxyprogesterone acetate (MPA) per kg body weight, once daily, was started and continued until Day 58 in order to prevent abortion due to progesterone deficiency. The endogenous plasma progesterone concentration decreased further, but pregnancy was maintained. On Day 59 a cesarean section was performed because of dystocia and four living and one dead pup were delivered. One puppy had severe facial malformations and was euthanised. The premature decrease in plasma progesterone concentration while ultrasonography demonstrated that the fetuses were still alive, and the maintenance of pregnancy during administration of MPA, strongly support the diagnosis of hypoluteoidism.