Comparison of the accuracy of two ultrasonographic measurements in predicting the parturition date in the bitch

OBJECTIVES: To compare the accuracy of two ultrasonographic measurements, inner chorionic cavity diameter and biparietal diameter, for the prediction of parturition date in small and medium size bitches. The effects of litter size and fetal sex ratio on the accuracy of the prediction were also investigated. METHODS: Ultrasonographic examinations were performed on pregnant bitches and, depending on the stage of pregnancy, the inner chorionic cavity diameter and biparietal diameter were measured. The mean value of the data of each structure was calculated and the predicted day of parturition was obtained by the application of equations derived from growth curves we previously developed for different size bitches. RESULTS: The parturition term was predicted with similar accuracy during early gestation, by the measurement of inner chorionic cavity diameter, as well as during late gestation, by the measurement of biparietal diameter. Litter size affected only biparietal diameter accuracy, whereas fetal sex ratio did not influence the estimation of the day of parturition. CLINICAL SIGNIFICANCE: Inner chorionic cavity diameter and biparietal diameter were equally reliable parameters in obtaining a reasonably accurate prediction of parturition date at any gestational period at which a bitch is examined.     

Establishment of the prediction table of parturition day with ultrasonography in small pet dogs

To establish a prediction table of parturition day the real-time B-mode ultrasonographic examinations were performed in the 8 pregnant Malteses and 10 Yorkshire terriers (total pups, 25 and 38 pups, respectively) from 18 days of gestation until the parturition. Ovulation was designated the first day of gestation (day 0). Extra fetal and fetal structures were measured from all conceptues. The parameters that exhibited the best correlation to parturition were used to compile a prediction table of parturition day. To testify the precision of the prediction table of parturition day, the 15 pregnant Malteses (48 pups) and 13 pregnant Yorkshire terriers (42 pups) with unknown mating time were examined using ultrasonography. Inner chorionic cavity diameter on days 18 to 37 and fetal head diameter on day 38 to parturition that showed the best correlation to gestational age were the most pertinent to the estimation of gestational age and the prediction of parturition day. The two parameters were used to compile a prediction table of parturition with averaged regression equations. In verificational examinations, with the exception of I Yorkshire terrier (3.6%) having 1 fetus, 18 of 28 bitches (64.3%) delivered exactly on the date predicted and 9 of 28 bitches (32.1%) delivered within I day of the date predicted. Therefore, the prediction table of parturition day seems to be a useful tool of the prediction of parturition day in practice.     

Prediction of parturition date in the bitch and queen

Assessment of gestational age and parturition date prediction is a challenging, yet common task in clinical management of the pregnant bitch or queen. Knowing the approximate parturition date is essential for a thorough pregnancy monitoring. Radiographic and ultrasonographic methods are suitable in bitches and queens. In the bitch, moreover, ovulation timing by means of LH or progesterone assay, determination of onset of vaginal dioestrus by means of examination of vaginal cytology, and recognition of impending parturition by monitoring prepartal progesterone levels and body temperature variation are practical methods. A combination of different methods increases the accuracy of parturition date prediction.     

Predicting the Parturition Date in Bitches of Different Body Weight by Ultrasonographic Measurements of Inner Chorionic Cavity Diameter and Biparietal Diameter

Predicting the parturition date in dogs by taking ultrasonographic foetometry has opened interesting research areas of veterinary obstetrics. Recently developed calculation formulas of inner chorionic cavity diameter (ICC) and biparietal diameter (BP) are formulas by Luvoni and Grioni ( 2000 ). This study is one of the first reports referring to ICC and BP with the use of Luvoni and Grioni formulas for predicting the parturition time in dogs of different body weight in clinical practice conditions. The research material consists of 70 clinically healthy pregnant bitches of 27 breeds and cross‐breeds. Bitches were divided into 4 groups according to their body weight. In each of the bitches, ultrasonographic examination of pregnancy was performed at least twice (ICC and BP measurements). Parturition dates for dogs with a body weight over 25 kg were calculated based on formulas intended for the group of medium dogs. It was caused by the lack of appropriate formulas for these groups of dogs. The predicting parturition dates were compared with the actual dates of delivery provided by the bitch owners. Generally, the results obtained in this study are very encouraging and similar or even better than those published by other authors using foetometric measurements. In our research, when comparing the effectiveness of predicting the delivery date based on foetometric formulas by Luvoni and Grioni ( 2000 ), it was proved that in all groups of dogs, even those over 25 kg, ICC and BP measurements at both accuracy levels were characterized similar reliability.     

Specific fetometric formulas of ICC and BP for calculating the parturition date in the miniature breeds of canine

The aim of this study was to derive the growth curves of the inner chorionic cavity and the biparietal distance in miniature dog breeds by ultrasonographic fetometry and present new specific formulas for prediction of parturition date. In this study, foetal biometry parameters were obtained using serial ultrasonographic examinations in 24 pregnant bitches of six different miniature breeds (≤5 kg). The mating time was unknown. Overall, 25 inner chorionic cavity diameter (ICC) and 22 biparietal diameter (BP) measurements were taken. The relationship between ICC or BP growth and days to parturition was analysed by linear regression. The results showed a significant relationship between days before delivery and ICC or BP. The equations derived from the growth curves can be used in practical prediction of parturition date in miniature dog breeds.     

Accuracy of prediction of canine litter size and gestational age with ultrasound

Different sonographic criteria have been developed to estimate canine fetal age, including fetal mensuration and assessment of fetal organ development. This retrospective study assessed the accuracy of gestational age and litter size predictions in 76 bitches using one of two techniques. The first method used the differential features of fetal organ development that occur in early and mid pregnancy, based on published tables for beagles. The second method used biparietal head and trunk diameters to predict gestational age based on tables published for late gestational Labrador Retrievers. The accuracy of the two methods was compared and the effect of maternal body weight and litter size evaluated. Litter size and maternal body weight did not affect the accuracy of gestational age prediction. Using a combination of both methods, the overall accuracy of predicting parturition date within 65 +/- 1 day and +/- 2 days was 70.8% and 86.1%, respectively. The correct litter size was predicted in 65% of cases, and in 89.5% of cases for +/- 1 pup. Pearson's correlation between actual litter size and predicted litter size was high (R = 0.957, P < 0.001). The organ development method of predicting gestational age was more accurate than late gestational fetal mensuration (P = 0.019). The optimum time for sonographic estimation of fetal age and litter size is early and mid pregnancy.     

Ultrasonographic Study of Deep Portion of Diencephalo-Telencephalic Vesicle for the Determination of Gestational Age of the Canine Foetus

The aim of this study was to evaluate the accuracy of ultrasonographic measurement of the deep portion of diencephalo‐telencephalic vesicle (DPTV) in the prediction of delivery date in different size bitches. The effects of litter size and foetal sex ratio on the accuracy were also investigated. For this purpose, the growth curve of DPTV was derived in large size dogs (26–40 kg) and the results of the accuracy of the prediction were compared with those obtained in small (≤10 kg) and medium (11–25 kg) size dogs by the application of the equations derived from the growth curve previously described. Ultrasonographic examinations were performed once a week during the second half of pregnancy in seven large size bitches (26–40 kg body weight). A linear regression model was adopted to analyse the relationship between the DPTV mean values and the days remaining to parturition. The results of regression analysis indicated that DPTV measurement in large size dogs is significantly and linearly related to the gestational age. Ultrasonographic measurements of DPTV were also performed during pregnancy in different size bitches with unknown breeding dates. Although the results indicated a similar accuracy of the prediction of the date of parturition in the different sizes of bitches, a higher accuracy was obtained in normal and large litter size compared with small litters. Foetal sex ratio did not affect the accuracy. In conclusion, this study demonstrated that the accuracy of the prediction of parturition day obtained by ultrasonographic evaluation of DPTV growth is reliable when specific formulae for different size dogs are applied. It should be noted that although foetal sex ratio does not affect the accuracy, the prediction could be less accurate when a small litter is present.     

Ultrasound evaluation of pregnancy and spontaneous embryonic resorption in the bitch

One hundred and one pregnant bitches were imaged using real-time B-mode ultrasonography. The accuracy of predicting fetal number was 38 per cent during early pregnancy and was lower with later examinations. If bitches were examined in early pregnancy and estimated to have five pups or more, or four pups or less, the predictive value of ultrasound was 100 per cent and 83-3 per cent, respectively. The ultrasonographic appearance of one case of abortion and five cases of isolated spontaneous embryonic resorption were characterised. The resorptions did not apparently interfere with adjacent remaining conceptuses. The components of embryonic resorption were found to be; reduced volume and changes in echogenicity of embryonic fluid, loss of embryonic mass and heartbeat, collapse of the conceptus with thickening and inward bulging of the uterine wall and reduced size in comparison with adjacent conceptuses. Following resorption the uterus was moderately hypoechoic in appearance, similar to after parturition. No risk factors were correlated with resorption or abortion.     

Ultrasonographic appearance of the uterus, placenta, fetus, and fetal membranes throughout accurately timed pregnancy in beagles.

Serial ultrasonographic examinations were performed on 8 Beagle bitches from 20 to 60 days pregnant to determine time of first detection, appearance, and sizes of selected features of pregnancy. Gestation was timed from the day of the preovulatory luteinizing hormone surge. Findings related to gestational age were consistent among bitches. Gestational ages at earliest detection of the following features were: chorionic cavity at day 20; placental layers in the uterine wall at day 22 to 24; zonary placenta at day 27 to 30; embryo and heartbeat at day 23 to 25; yolk sac membrane at day 25 to 28; allantoic membrane at day 27 to 31; choroid plexus of the brain at day 31 to 35; fetal movement at day 34 to 36; skeleton at day 33 to 39; bladder and stomach at day 35 to 39; kidney at day 39 to 47; and liver hypoechoic, compared with lung, at day 38 to 42. Extra-fetal structures were measurable from day 20 or 22 through day 48. Chorionic cavity diameter increased from 0.2 +/- 0.0 cm to 3.3 +/- 0.2 cm, outer uterine diameter increased from 0.8 +/- 0.03 cm to 4.8 +/- 0.2 cm, length of chorionic cavity or zonary placenta increased from 0.3 +/- 0.03 cm to 4.9 +/- 0.05 cm, uterine wall thickness increased from 0.3 +/- 0.03 cm to 0.8 +/- 0.01 cm, and placental thickness increased from 0.1 +/- 0.0 cm to 0.5 +/- 0.05 cm. Chorionic cavity diameter, outer uterine diameter, and placental length each increased at a linear rate through day 37, after which time, each had a marked plateau in growth. Of the extra-fetal structures, chorionic cavity diameter was the most accurate for estimation of gestational age. All of the fetal structures studied increased at an increasing (second order) rate. Crown-rump length increased from 0.3 +/- 0.05 cm on day 24 to 9.2 +/- 0.2 cm on day 48. Body diameter increased from 0.2 +/- 0.03 cm on day 24 to 4.6 +/- 0.15 cm on day 60. Head diameter increased from 0.8 +/- 0.05 cm on day 34 to 2.7 +/- 0.04 cm on day 60. Of the fetal structures, head diameter was the most accurate for estimation of gestational age.     

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.     

Sonography during the pregnancy of sheep. I. Fetometry for the determination of the stage of gestation and prediction of the time of parturition]

Transrectal and transcutaneous ultrasonography was performed on 187 pregnant Merino ewes to measure the growth of fetal parameters (fetometry) such as the diameters of the eye, braincase and trunk, the width of one rib with its intercostal space and the crown-rump-length (CRL). In the ewes, cross and longitudinal diameters of the intrauterine lumen around the embryo and fetus were determined. Trunk diameter and crown-rump-length of embryos and fetuses were sonographically determined from Day 26 and size of eyes, braincase and ribs were measured from Day 52 to 66 of gestation. Embryonic resp. fetal parameters and uterine diameters showed almost linear growth rate. Relationship between the measured parameters and days of pregnancy is described by regressions and correlation coefficients. Correlation coefficient between gestational stage and the diameter of the trunk was very narrow (r = 0.98) and between gestational stage and the crown-rump-length resp. eye diameter equalled 89% (r = 0.89). These fetal parameters are appropriate to assess gestational age and growth of ovine fetuses. It can be concluded that sonographic fetometry in the ovine can be valuable for the evaluation of fetal development, the estimation of gestational age and the prediction of parturition dates.     

Comparative evaluation of three different formulas for predicting the parturition date of German Shepherds following somatic cell nuclear transfer

Several studies have reported methods to estimate the parturition date of dogs using ultrasonographic measurements. However, these prediction models were mainly determined using ultrasonographic measurements of naturally pregnant small- and medium-sized dogs, and no such studies have been performed using dogs carrying cloned fetuses produced via somatic cell nuclear transfer. The present study evaluated the abilities of three reference formulas (Luvoni and Grioni, Milani et al., and Groppetti et al.), all of which were developed using data from naturally occurring pregnancies, to accurately predict the parturition date in surrogates carrying cloned German Shepherd (GS) fetuses. All three formulas were based on the use of inner chorionic cavity diameter (ICC) measurements, obtained via ultrasonography. For evaluation, a total of 54 ICC measurements were collected from 14 pregnant bitches carrying cloned GS fetuses. We found that the clinical accuracy of the breed-specific Groppetti et al. formula was highest among those of the three formulas tested, with 87% and 100% of the estimated parturition dates (calculated based on the ICC measurements) being within 1 and 2 days, respectively, of the actual delivery date. By contrast, the Luvoni and Grioni formula showed relatively low accuracy, and the Milani et al. formula showed higher accuracy than that reported previously for natural pregnancies.     

超声断层扫描观察苏北犬胚胎和胎儿发育

用5MHz线阵探头对14只母犬从配种后18d开始，每2d用B超探查1次；配种后36～48d，每3d探查1次；48d以后，于52、57d各探查1次。结果表明，于配种后18～22d确诊7只犬妊娠，7只空怀。有3只犬分剐在配种后24、36、39d发生流产。观察胎囊、胎儿、胎心、胎动、胎儿脏器、胎儿骨骼出现时间和测量胎囊大小、冠臀长、胎儿身长、头长、双顶径、胸深和心区大小，证明胎囊大小、胎儿冠臀长、身长、头长、双顶径、胸深与胎龄呈显著正相关。在配种后18～30d，观察子宫暗区大小可预测胎龄。在配种32d以后，观测胸深、双顶径或头长。可精确预测胎龄。     

The use of ultrasonography for pregnancy diagnosis in the bitch

Twenty-three Greyhound bitches housed at 3 breeding kennels were examined for pregnancy via transabdominal palpation and ultrasonography. Pregnancy was timed from the calculated day of ovulation (day of ovulation = day when first pup was whelped--63), and from a single breeding date (day 0). Starting on day 10 after ovulation, 9 bitches were monitored every 3 days by ultrasonography only, to determine gestational vesicle sizes during gestation and the time when fetal movements and heartbeats could be first detected. The other 14 bitches were examined by ultrasonography and transabdominal palpation on the same day every week, starting on postovulation day 19, to compare the effectiveness of the 2 methods of pregnancy determination. Parturition was the final determinant of pregnancy status. The earliest correct diagnosis of pregnancy was at 18 days after ovulation, but fetal movements and heartbeat could not be identified until days 28 and 35, respectively. Estimation of fetal numbers by ultrasound or palpation was not reliable when there were more than four in the litter. Pregnancy and nonpregnancy were correctly determined by both methods in an increasingly greater number of bitches as gestation progressed, but ultrasonography was more accurate at all stages; on days 19 to 22, 26 to 30, 34 to 38, and greater than 40 after ovulation, correct diagnoses were made in 33%, 42%, 50%, and 75% of the bitches by palpation and in 42%, 67%, 75%, and 83% of the bitches by ultrasonography. The most common error was failure to detect pregnancy by palpation or ultrasonography in bitches with small litters and tense abdominal muscles.(ABSTRACT TRUNCATED AT 250 WORDS)     

ULTRASOUND PREDICTION OF PARTURITION IN QUEENS

Eight pregnancies in five queens were followed with serial ultrasound examinations. Measurements of head and body diameter were made throughout pregnancy. These measurements were used to produce individual growth curves for each pregnancy and average curves for both head and body diameter. Formulas based on the slope of the growth curves were derived. These formulas were then used to predict parturition dates based on single measurements of fetal head and/or body diameter in eight additional queens. Predicted date of parturition was then compared to actual queening dates. Ultrasound prediction of parturition date was accurate to within two days in seven of eight queens.     

Evaluation of von Willebrand Factor During Pregnancy,Lactation and Oestrous Cycle in Bitches Affected and Unaffected by von Willebrand Disease

Plasmatic concentrations of von Willebrand Factor (vWF) increase during pregnancy in humans and dogs; however the mechanism of such increase is still not well defined. The aims of this study were: (i) to evaluate changes in vWF concentration during pregnancy and during the subsequent oestrous cycle in bitches affected and unaffected by von Willebrand Disease (vWD); (ii) to correlate the vWF levels and cortisol levels in both groups. Seven vWD affected (GI) and nine unaffected (GII) bitches were used. The animals were assessed during pregnancy, parturition, lactation and non‐gestational oestrous cycle in 11 moments (Pregnancy 1, Pregnancy 2, Parturition, Lactation 1, Lactation 2, Lactation 3, Anestrus, Proestrus, Oestrus, Diestrus 1, and Diestrus 2). The following tests were performed; measurement of von Willebrand factor antigen (vWF:Ag), albumin and cortisol. In both groups, vWF concentration remained stable during the non‐gestational oestrous cycle, but increased during pregnancy, with the highest value observed at parturition. Increases of 70% and 124% in vWF were seen in GI and GII, respectively, compared to anestrus. No correlation was found between vWF and cortisol. Values of vWF:Ag changed during pregnancy, with a peak at parturition, both in vWD affected and unaffected animals. Values of vWF were not altered in the different phases of the oestrous cycle following pregnancy in both groups. Evaluation of vWF during pregnancy can cause false negative results for vWD, but assessment can be performed at any point in the oestrous cycle of non‐pregnant bitches.     

Early pregnancy diagnosis by means of ultrasonography as a method of improving reproductive efficiency in goats

Eighteen cyclic Shiba goats were used in this study. Estrus was synchronized with a single injection of 125 microg of a synthetic analogue of prostaglandin F(2)alpha (PGF(2)alpha) after detection of at least one corpus luteum by B-mode ultrasonography. Blood samples were collected from each animal on days 0, 7 and 21 post-mating for progesterone assay. Animals in estrus were either allowed to be mated by fertile bucks twice during estrus (group I; n=12) or not at all (group II; n=6). Ultrasonographic examinations were performed transrectally or transabdominally using a real-time B-mode scanner equipped with a 7.5 or 5 MHz transducer. All animals exhibited estrus 56.0 +/- 2.7 h after injection of PGF2alpha. The results show that the accuracy of the progesterone assay in diagnosing pregnancy on day 21 after mating was 80% for pregnancy and 100% for non-pregnancy, retrospectively. Ultrasonographic examinations showed that gestational sac and embryos heartbeats were detected on days 20.2 +/- 0.6 and 24.3 +/- 0.7 of gestation, respectively. Placentomes were detected on day 35.4 +/- 1.0 of gestation as small nodules (0.7 +/- 0.2 cm in size). At two months pregnancy, skeletal structures like skull, thorax and long bones were clear. Biparietal diameter of the skull and length of long bones could be used as an estimate of gestational age. The accuracy of detection of fetal number using real-time B-mode ultrasonography was 91.7% on day 60 of gestation. In conclusion, progesterone assay at day 21 post-mating (cut-off value, 1 ng/ml) can be used for pregnancy diagnosis in goats. However, B-mode transrectal ultrasonography was more efficient due to detection of embryo and confirmation of its viability by heartbeats. In addition, fetal number and gestational age could be determined only by ultrasonography.     

Estimated pregnancy length from ovulation to parturition in the bitch and its influencing factors: a retrospective study in 162 pregnancies

An accurate timing of parturition is very useful for managing canine parturition. It is generally accepted that parturition in bitches occurs between 64 and 66 days after the luteinizing hormone peak. In this retrospective study, we determined pregnancy length in different breeds and its influencing factors dating it from the estimated day of ovulation (EDO), defined as the day when peripheral plasma level of progesterone (P4) reaches 6 ng/ml. From January 2001 to December 2006, 162 pregnancies in 151 bitches of 53 different breeds were followed. Different parameters concerning the bitch, the litter, the type of semen and the type of reproduction were studied. The mean estimated pregnancy length in the bitch from EDO to parturition was 63.1±2.1 days. The main influencing factors for the pregnancies studied were the breed, the size of the bitch and the number of puppies within the litter.     

Canine fetal echocardiography: correlations for the analysis of cardiac dimensions

The aim of this study was to develop regression models for correlation of canine fetal heart development with body size to characterize normal development or suggest cardiac anomalies. Twenty clinically healthy pregnant bitches, either brachycephalic and non-brachycephalic, were examined ultrasonographically. Transabdominal fetal echocardiography was conducted every 4 days from the beginning of cardiac chambers differentiation until parturition. Ten cardiac parameters were measured: length, width and diameter of the heart; heart area; left and right ventricular dimensions; left and right atrial dimensions; and aortic and pulmonary artery diameter. Femoral length, biparietal diameter and abdominal cross-sectional area were also recorded. Regression equations were developed for each parameter of fetal body size, and linear and logarithmic models were compared. The model with the highest correlation coefficient was chosen to produce equations to calculate relative dimensions based on the correlations. Only the left-ventricular chamber differed between the two racial groups. Biparietal diameter was the independent parameter that produced the highest correlation coefficient for the most fetal cardiac dimensions, although good correlations were also observed using femoral length and abdominal cross-sectional area. Heart width and heart diameter were used as surrogates of cardiac development, as these measurements showed the best statistical correlation. Quantitative evaluation of fetal cardiac structures can be used to monitor normal and abnormal cardiac development.     

Association between gestational age and bovine fetal characteristics measured by transcutaneous ultrasound over the right flank of the dairy cow

Objective   To determine bovine fetal characteristics significantly associated with increasing gestational age as measured via transcutaneous ultrasonography over the right flank.
Methods   The length of gestation at date of pregnancy diagnosis via transcutaneous and transrectal ultrasonography was determined for 224 dairy cattle by estimation from subsequent calving dates. A separate dataset was created for each measurable fetal characteristic (i.e. thoracic diameter, abdominal diameter, umbilical diameter, placentome length and placentome height) and risk factors significantly associated with gestational age at pregnancy diagnosis within each dataset, including the fetal characteristic, were identified.
Results   Abdominal diameter was the most frequently observed fetal characteristic and thoracic diameter was the least. Gestational age at pregnancy diagnosis (d) was significantly associated with fetal thoracic diameter (P < 0.01), abdominal diameter (P < 0.01) and umbilical diameter (P = 0.02) when measured via transcutaneous ultrasound. Within each model, sire breed, dam breed, dam age and/or calf sex were also significantly associated with gestational age. Gestational age at pregnancy diagnosis was not significantly associated with either placentome height or length (P > 0.05).
Conclusion   Fetal thoracic diameter, abdominal diameter and umbilical diameter were found to be significantly associated with gestational age between approximate days 73 to 190 of gestation. Transcutaneous ultrasonography may prove a useful method of estimating gestational age in the absence of accurate breeding records.