Maternal age and parity influence ultrasonographic measurements of fetal growth in Dutch Warmblood mares

Estimation of gestational age in buffaloes (Bubalus bubalis) by transabdominal and transrectal ultrasonography

The aims of the presented study were (1) to examine the relationship between foetal measurements and gestational age (GA), (2) to generate GA formulas, and (3) to investigate the estimation of GA by transabdominal ultrasonography in buffaloes. Thirteen pregnant buffaloes were used in the study. Transrectal ultrasonography was performed between Day (D) 28 and 112 of gestational age, whereas transabdominal ultrasonography was between 126 and 294. The diameters of embryonic (EVD) and amniotic (AVD) vesicles, crown-rump length (CRL), occipito-nasal length (ONL), biparietal diameter (BPD), orbit diameter (OD), cervical, thoracic, lumbar and coccygeal vertebrae lengths (CVL, TVL, LVL, CcVL), abdominal diameter (AD), chest diameter (CD), umbilical cord diameter (UCD), scapula, humerus, radius-ulna, metacarpus, femur, tibia, and metatarsus lengths (SL, HL, RUL, McL, FL, TL, MtL), diameters of transversal heart (THD), stomach (SD), kidney (KD), and outer diameter, circumference and area of placentomas (OPD, OPC, OPA) were measured by ultrasonography. All 26 parameters were highly correlated with GA (r = 0.968 - 0.999). The observation of the foetus was evident in all animals via transabdominal ultrasonography, and all parameters except EVD, AVD, and CRL could be measured on D 126. In addition, heartbeats, the sign of foetal vitality, could be observed in 11 of 13 living foetuses. This study is the first to demonstrate that transabdominal ultrasonography can be used to estimate GA in buffaloes. In addition, GA formulas related to ONL, CVL, TVL, LVL, CcVL, extremity bone lengths, THD, UCD, PC, and PA measurements were created for the first time in buffaloes.

Gestation Length is Associated With Early-Life Limb Deformities in Thoroughbred Foals

Flexural and angular limb deformities (LD) are an important cause of early-life morbidity and mortality/euthanasia in Thoroughbred foals. The majority are congenital in origin but, to date, their precise aetiology is poorly understood. We hypothesized that maternal- and pregnancy-level factors, particularly those with potential to influence in-utero growth and development, could play an important role. The aim of this study was therefore to investigate associations between such factors and early-life LD in Thoroughbred foals. A birth cohort was established on seven farms across the United Kingdom and Ireland and details of veterinary interventions for LD in foals in the first six months of life prospectively recorded. Details of dams' signalment, breeding history and reproductive and veterinary history in the breeding season(s) of interest were retrieved retrospectively from stud farm and veterinary records. Associations between mare- and pregnancy-level factors and LD in offspring were assessed using multivariable logistic regression. Records were available for 275 pregnancies in 235 mares, over two breeding seasons. Pregnancies resulted in the birth of 272 live foals, 21% of which (n = 57/272, 95% CI, 16-26) required veterinary intervention for LD in the first six months of life. Odds of LD decreased by 4% per day increase in gestation length between 314 and 381 days (OR 0.96, 95% CI, 0.93-0.99, P = .01). Longer gestation length appears to reduce the odds of early-life LD, including within the normal range of gestation length for Thoroughbred foals. Further work is required to elucidate biological mechanisms behind this association.

Pregnancy monitoring in mares: Ultrasonographic and endocrine approaches

Methods to diagnose and monitor equine pregnancy continue to advance with improved instrumentation enabling the development of novel, non-invasive approaches to assess fetal well-being and viability using ultrasound and endocrine testing. From early embryonic loss to placentitis, that is typically encountered later in gestation, fetal viability and development as well as placental function can be evaluated using two fundamentally different, structural and functional, approaches. Ultrasound provides structural information on embryonic and fetal growth using such parameters as combined thickness of the uterus and placenta (CTUP), visual assessment of fetal fluids, activity, heart rate and multiple biometrics involving the fetal head and eyes, limbs and joints among many others, depending on the stage of gestation. Endocrine profiles that include progesterone and 5α-dihydroprogesterone, other metabolites, androgens and estrogens can be evaluated simultaneously using liquid chromatography-tandem mass spectrometry (LC-MS/MS) providing more functional information on fetal and placental competence and development. Endocrine information can be used in making clinical decisions including the need for progestin supplementation or when it can cease, and even estimating gestational stage in mares that cannot be easily palpated or scanned, as with mini-breeds or rancorous animals most notably. When used together, monitoring gestation by ultrasound and hormonal analysis provides unusual insight into feto-placental well-being and the progress of pregnancy, helping to identify problems needing therapeutic intervention.

Adaptive response of estrogen-iron axis in pregnant Purebred Spanish mares of different age

The maintenance of iron (Fe) homeostasis is vital for the physiological function along life. In sexually mature humans and experimental animals, estrogens downregulate hepcidin (Hpc) expression, in order to improve the intestinal absorption and to mobilize Fe stores for maternal erythropoietic expansion and placental development. However, changes of these mechanisms related to regulation of Hpc on the availability of Fe during gestation with advancing age in mares, remain unknown. The objective of this study was to evaluate the interrelationships between serum Fe, Ferritin (Ferr) and Hpc with estrone (E₁) and estradiol-17β (E₂) concentrations in pregnant mares of different ages. Blood samples were taken from 40 pregnant Spanish Purebred mares belonging to 4 different age groups, 10 subjects for each group: 4-6 years, 7-9 years, 10-12 years, and > 12 years were used in this study. Fe concentrations of 4-6 and 7-9 years groups were higher (P < .01) than 10-12 and >12 years groups. Ferr concentrations of 4-6 years group were higher (P < .01) than other groups. Hpc concentrations increased and E₁ decreased (P < .01) in > 12 years group compared to other age groups. E₂ concentrations of 7-9, 10-12 and >12 years groups were higher (P < .01) than those of 4-6 years group; 7-9 years group had higher E₂ concentrations (P < .01) than > 12 years group. Fe and Ferr were negatively correlated with Hpc (r = -0.81 and r = -0.67, respectively). E₁ and E₂ were negatively correlated with Fe (r = -0.23 and r = -0.11, respectively). E₂ was positively correlated with Hpc (r = 0.78). In pregnant Spanish Purebred mare, the increase of estrogens, according to the more efficient iron status in response to Hpc inhibition and consequent mobilization of circulating and iron reserve, shows the existence of "estrogen-iron axis" in young mares. Nevertheless, these mechanisms are reversed in old mares, suggesting a less efficient iron metabolism with advancing age. It is hoped that new investigations are needed to understand in depth and clarify further the complex metabolic and hormonal mechanisms involved also in equine species.

The effects of aging and gestational month on uteroplacental vascular perfusion, and umbilical artery hemodynamics in pregnant jennies

This study aimed to correlate the pulsed wave spectral indices of the middle uterine artery at both sides with placental development in jenny within mid-late pregnancies, and establish umbilical Doppler values for different ages and different gestational months. Twenty Equus Asinus pregnant jennies 260-450 kg (average, 320 ± 10 kg) were examined from 5 to 9 months of pregnancy with different ages (4-14 years). Monthly B-mode ultrasound examination was performed on both the combined thickness of the uterus and placenta (CTUP; mm) and umbilical artery cross-sectional diameter, and Doppler mode examination was performed on both the middle uterine (MUA at right [R] and left [L] sides) and umbilical arteries to measure both Doppler indices that expressed by resistance (RI) and pulsatility indices (PI), and blood flow rate. CTUP was elevated within pregnancy time at different ages (P < 0.05). L. PI was significantly declined throughout different ages (P < 0.05), but this declining trend was not observed in L. RI. The L. blood flow rate (R; bpm) was elevated among different ages and different months (P < 0.05). Both RI and PI were significantly decreased from 5 to 9 month of gestation period in jennies (P < 0.05).. The umbilical arteries cross-sectional diameter (Umb A; mm), was elevated among different ages and different months, while both Doppler indices were declined. A positive correlation was found (between both Doppler indices of both umbilical and uterine arteries P < 0.001). There was elevated vascular perfusion in uterine and umbilical arteries associated with reduced both Doppler indices along the course of pregnancy at different ages.

Female age and parity in horses: how and why does it matter?

Although puberty can occur as early as 14-15months of age, depending on breed and use, the reproductive career of mares may continue to advanced ages. Once mares are used as broodmares, they will usually produce foals once a year until they become unfertile, and their productivity can be enhanced and/or prolonged through embryo technologies. There is a general consensus that old mares are less fertile, but maternal age and parity are confounding factors because nulliparous mares are usually younger and older mares are multiparous in most studies. This review shows that age critically affects cyclicity, folliculogenesis, oocyte and embryo quality as well as presence of oviductal masses and uterine tract function. Maternal parity has a non-linear effect. Primiparity has a major influence on placental and foal development, with smaller foals at the first gestation that remain smaller postnatally. After the first gestation, endometrial quality and uterine clearance capacities decline progressively with increasing parity and age, whilst placental and foal birthweight and milk production increase. These combined effects should be carefully balanced when breeding mares, in particular when choosing and caring for recipients and their foals.

Prediction of the onset of parturition in horses and cattle

Economic losses due to dystocia or neonatal death as well as animal welfare and ethical concerns demand a reliable prediction of parturition with the aim to improve survival of the dam and her offspring. In this review, estimation of gestational age by ultrasound and prediction of parturition based on clinical signs, behaviour changes and changes in body temperature, composition of mammary gland secretions as well as hormonal changes are discussed in comparison between horses and cattle. Based on the physiological changes associated with the end of gestation and onset of labor, several systems and methods to predict parturition in horses and cattle have been developed. Physiological differences related to breed, maternal age and parity, pathological changes due to intrauterine growth retardation, placental problems or general illness of the dam but also housing and management systems bias a reliable prediction of parturition. This may be acceptable in cattle as long as birth alarm systems give satisfying results at herd level. The situation is different in the horse where the economic and emotional value of an individual mare and her foal usually reaches different dimensions than in cows. The possibilities for prediction of parturition can thus be discussed together, the consequences, however, may differ considerably between the two species.

A regression model including fetal orbit measurements to predict parturition in Standardbred mares with normal pregnancy

In the mare, foaling is a critical unpredictable event due to a wide range of gestational length and the absence of clear signs of impending parturition. To predict foaling, pH, inversion sodium potassium and increase of calcium concentration in mammary secretions are used. The aim of this study was to find how many days are left until parturition knowing mare's age (A) and parity (P) combined with ultrasonographic measurements of the fetal orbit in Standardbred mares with normal pregnancy. Eighty healthy Standardbred mares with normal pregnancy were hospitalized for attended delivery. Information about mare's age, parity and breeding date were recorded at admission. Transrectal ultrasonography were routinely performed at admission and every 10 days until parturition using a B-mode real time portable unit equipped with a 5-7.5 MHz linear transducer. The images of the fetal orbit were acquired when cornea, anterior and posterior chamber, vitreous body, lens and optic nerve were visible. Longitudinal diameter (LD) was considered as the distance between the two ocular poles, within the vitreous body; transverse diameter (TD), perpendicular to LD and bisecting the lens, was measured as the distance between cornea and retina. At delivery, length of pregnancy and gestational age at each exam were registered. For each ultrasound examination, days before parturition (DBP) were calculated. Seventy-eight Standardbred mares with normal pregnancies were included in the study. Mares' mean age was 9 ± 5 years old (range 4-20 years) and mean gestation length was 341 ± 7 days (range 327-366 days). Thirty-three mares were primiparous and 45 mares were multiparous. Data were analyzed using a regression tree: P, A, LD and TD were used as covariates. DBP was used as the variable of interest. Nine terminal nodes were identified based on the selected covariates. The first split is produced by the TD: fetuses with TD greater or equal than 2.97 cm are further split according to LD, with a threshold of 3.28 cm. The next split is dictated by A; after a further split on LD, the first terminal node is built, containing 34 fetuses with average DBP equal to 10 days. If the A is ≥ 9.5 years a further split is on P: when mares are multiparous, the TD built two different nodes. Since prediction of mare's foaling date is an important factor in stud farm management, the regression model developed may help the veterinarian to estimate the DBP in Standardbred mares with normal pregnancy.

Transrectal three-dimensional fetal volumetry and crown-rump length measurement during early gestation in mares: Intra- and inter-observer reliability and agreement

The aim of this study was to investigate if transrectal three-dimensional (3D) ultrasound is a reliable technique to measure equine fetal volume (FV) during early gestation in mares. In total 149 warmblood mares were examined once transrectally on days 45 ± 1 of pregnancy with a portable 3D ultrasound device (Voluson^® i, GE Healthcare, Zipf, Austria). The following measurements were performed: Two-dimensional (2D) and 3D crown-rump length (CRL), FV using Virtual Organ Computer-aided AnaLysis (VOCAL™) software with rotational angles of 6° and 30°. To analyze intra- and inter-observer reliability (intraclass correlation coefficient (ICC)) and agreement (Bland-Altman's limits of agreement (LoA)) of FV measurements, images from 60 horse fetuses were selected and repeatedly analyzed by the same examiner (A) and by a second examiner (B). The time for each ultrasound examination (2D and 3D) and for the FV measurements was recorded. The 3D measured CRL was larger (P < 0.001) than the 2D CRL. Repeated measurements of 3D CRL showed a higher reliability (ICC = 0.91 (0.88-0.94), P < 0.001) and agreement (mean = 0.13%, 95% LoA: 7.45 to +7.19) compared to reliability (ICC = 0.50 (0.36-0.61), P < 0.001) and agreement (mean = -1.54%, 95% LoA: 23.29 to +20.21) of the CRL measurement in 2D mode. For intra-observer examinations, reliability was highest when using a rotational angle of 30° (ICC = 0.98 (0.97-0.99), P < 0.001). The inter-observer reliability of 3D measurements was good (ICC = 0.85 (0.67-0.92), P < 0.001). The extra time needed to perform the 3D scan ranged from 1 to 9 min and FV measurements lasted 03:30 ± 00:46 and 08:10 ± 01:05, for rotational angles of 30° and 6°, respectively. In conclusion, this study showed a high level of intra- and inter-observer reliability and agreement for FV measurements using VOCAL™. Furthermore, the 6° and 30° rotational angles can be used interchangeably, but test duration, reliability and agreement were better with the 30° rotational step method. The CRL measurements obtained with 3D mode probably reflects the true CRL, compared to the 2D measured CRL.

Effects of season on placental, foetal and neonatal development in horses

Seasonal changes in metabolic rate have been shown in horses and we hypothesized that this leads to the birth of smaller foals early in the year. Mares and their foals were assigned to three groups by day of foaling within the year (e.g. 1 January = day 1): Group 1 (n = 10) day 40-65, group 2 (n = 8) day 67-92, group 3 (n = 9) day 94-121. Groups did not differ with regard to parity. In foals, height at withers and body weight were determined on days 1-5 and weekly until 12 weeks of age. Chest circumference, distances fetlock to carpus, carpus to elbow, poll to nose and crown-rump length were determined on day 5 and weekly until 12 weeks of age. Placental weight (p < 0.05) and surface (p < 0.01) were lower in mares of group 1 than in groups 2 and 3. Foal weight and length measurements increased over time (p < 0.001). Height at withers was consistently lower in group 1 than in groups 2 and 3 (p < 0.05) while foal weight did not differ among groups. Fetlock to carpus, carpus to elbow (both p < 0.01) and poll to nose length (p < 0.05) were lower in group 1 than in groups 2 and 3. Neither gestation length nor sex ratio of foals differed among groups. In conclusion, foetal size is reduced when the final growth phase coincides with the winter months. This also impacts neonatal growth during the first three months of life.

The development of locomotor kinetics in the foal and the effect of osteochondrosis

Reason for performing study

Foals stand and walk immediately after birth, but insight into the subsequent longitudinal development of their gait kinetics in the early juvenile phase and the possible influence of osteochondrosis thereon is lacking.

Objectives

To quantify gait kinetics in foals during the first half year of life, taking into account their osteochondrosis status.

Study design

Prospective, cohort study performed at a single stud farm.

Methods

Pressure plate measurements at walk and trot from 11 Dutch Warmblood foals during the first 24 weeks of life were used to determine body mass normalised peak vertical force, normalised vertical impulse and stance duration. Coefficients of variation of peak vertical force and stance duration were used as measures for gait maturity. Radiographs of tarsocrural and femoropatellar joints were taken at age 4–6 weeks and after 6 months to check for osteochondrosis. A linear mixed model was used to determine the effects of age, limb, presence of osteochondrosis and speed on gait parameters.

Results

Mean walking and trotting velocity increased over time as did stance duration and normalised vertical impulse, normalised peak vertical force values however remained relatively constant. During the first weeks of their life only the coefficient of variation of stance duration decreased significantly, while the coefficient of variation of peak vertical force did not. None of the foals was visibly lame, but the presence of osteochondrosis resulted in a temporarily but significantly reduced normalised peak vertical force.

Main limitations

This study is a relatively small sample size of one breed from a single stud farm. A stand‐alone pressure plate was used and body mass was estimated rather than measured.

Conclusions

Despite being precocious, foals need time to mature their gait. During growth, velocity at walk and trot increases, but normalised peak vertical force remains relatively constant. Although not visibly lame, a temporary reduction in normalised peak vertical force was detected in osteochondrosis positive foals using a pressure plate.

Transrectal ultrasonographic evaluation of combined utero-placental thickness during the last half of pregnancy in Martina Franca donkeys

In the recent years, the donkey population decreased dramatically so that many breeds are presently considered as endangered. In comparison to the horse, the donkey placenta still remains not completely studied. In the horse, one of the diagnostic tools useful to identify pregnant mares at risk of abortion or premature delivery, include the transrectal ultrasound examination of the uterus and its contents; and especially of the combined thickness of the uterus and of the placenta (CUPT). Since the CUPT was never investigated in donkeys, the present study was aimed to define the transrectal CUPT values during the last half of pregnancy in 20 Martina Franca jennies. Foalings times, foals characteristics and placental gross appearance, and measurements were also evaluated and values resulted always within normality. Differently to the mare, a continuous significant CUPT increase between the sixth to the 12 months of pregnancy, and a substantial increase from the ninth to the 12th month of pregnancy, was found. Although statistically not evaluable, the CUPT values recorded from three jennies with pregnancy loss did not show evidence of CUPT increases. In conclusion, normal CUPT values from the sixth to the 12th month of pregnancy in Martina Franca donkeys are provided, but further investigations are needed to define possible breed or body-size CUPT specific differences, as well as the CUPT values during pregnancy disturbances or placental abnormalities.

Trabecular bone of precocials at birth; Are they prepared to run for the wolf(f)?

Bone is a dynamic tissue adapting to loading according to “Wolff's law of bone adaptation.” During very early life, however, such a mechanism may not be adequate enough to adapt to the dramatic change in environmental challenges in precocial species. Their neonates are required to stand and walk within hours after birth, in contrast to altricial animals that have much more time to adapt from the intrauterine environment to the outside world. In this study, trabecular bone parameters of the talus and sagittal ridge of the tibia from stillborn but full‐term precocials (calves and foals) were analyzed by micro‐CT imaging in order to identify possible anticipatory mechanisms to loading. Calculated average bone volume fraction in the Shetland pony (49–74%) was significantly higher compared to Warmblood foals (28–51%). Bovine trabecular bone was characterized by a low average bone volume fraction (22–28%), however, more directional anisotropy was found. It is concluded that anticipatory strategies in skeletal development exist in precocial species, which differ per species and are most likely related to anatomical differences in joint geometry and related loading patterns. The underlying regulatory mechanisms are still unknown, but they may be based on a genetic blueprint for the development of bone. More knowledge, both about a possible blueprint and its regulation, will be helpful in understanding developmental bone and joint diseases. J. Morphol. 277:948–956, 2016. © 2016 Wiley Periodicals, Inc.

Transabdominal ultrasonography for pregnancy diagnosis and estimation of gestational age in dromedary camels

The objective of this study was to evaluate the use of transabdominal ultrasonography as a method for pregnancy diagnosis and establish some foetal biometrics guidelines of pregnancy staging. Transabdominal ultrasonography was performed weekly on six pregnant camels from the 4th to the 19th week and at 2-week intervals from the 20th to the 52nd week of gestation. Six areas were selected for examination: caudal abdominal (CAA), inside the thigh, above the base of the udder; middle abdominal (MIA), from the base of the udder to the umbilicus; and cranial abdominal (CRA), from the umbilicus to the xiphoid cartilage. Several foetal parameters including orbital diameter (ORD), biparietal diameter (BPD), abdominal diameter (ABD), chest depth (CHD) and ruminal diameter (RUD) were measured using standardized scan plans. The relationships between the gestational age and the foetal parameters were evaluated. From the 6th to the 12th week, the conceptus was always observed through the left CAA approach. Between the 13th and 27th week, the foetus was entirely visualized by the MIA examination. From the 28th to the 52nd week, the conceptus was mainly detected through the left CRA approach. The foetal parameters were measured frequently during mid- and late gestation. All regression and correlation coefficients were highly significant (p < 0.0001). In conclusion, transabdominal ultrasonography was shown to be a reliable technique for pregnancy diagnosis and estimation of gestational age in dromedary camels.

Ultrasonographic evaluation of equine fetal growth throughout gestation in normal mares using a convex transducer

It has not been common to perform regular ultrasound examination of the fetus in equine practice, due to the increasing volume of the uterus caused by fetal development. The convex three-dimensional transducer is bulb-shaped and is able to observe wide areas. In addition, its operation is simple, making it easy to create appropriate angles for various indices using a transrectal approach. The aim of this study was to measure Thoroughbred fetal growth indices throughout gestation using a convex transducer and to clarify the detectable period of some indices for clinical use. We demonstrated changes in fetal indices, such as crown rump length (CRL), fetal heart rate (FHR), fetal eye and kidney and the combined thickness of uterus and placenta (CTUP). CTUP increased from 30 weeks of gestation, and FHR peaked at 8 weeks and then decreased to term. CRL could be observed until 13 weeks due to its wide angle, longer than in previous reports. Fetal eye and kidney could be observed from 10 and 28 weeks, respectively, and these increased with pregnancy progress. The present results showed the advantage of transrectal examination using a convex transducer for evaluation of normal fetal development. Although ultrasonographic examination in mid- to late-gestation is not common in equine reproductive practice, our comprehensive results would be a useful basis for equine pregnancy examination.