Ultrasound aspects of fetal and extrafetal structures in pregnant cats

Expression of Anti-Müllerian Hormone and Its Type 2 Receptor in the Ovary of Pregnant and Cyclic Domestic Cats

To evaluate the expression of AMH and its receptor AMHRII, ovaries of 33 p cats were investigated by western blot and immunohistochemistry. After ovariohysterectomy, the cats were grouped according to pregnancy stages and ovarian/placental endocrine activity: group I (n = 3, 24−29 days), II (n = 8, 32−40 days), III (n = 4, 41−46 days), IV (n = 6, 53−61 days) and according to cycle stages: V (n = 6, interestrus) and VI (n = 6, estrus). Serum progesterone- and AMH-concentration was measured. Follicle numbers did not differ between groups. The number of corpora lutea was higher in pregnant cats than in the non-pregnant cats. Serum AMH concentration was at maximum between day 30 and 50 of gestation, and was higher than in non-pregnant cats, then decreased towards term (p < 0.05). In the ovaries, AMH immunopositivity was observed in granulosa cells of secondary and antral follicles, and in interstitial cells of corpora lutea; highest percentage of immunopositive areas was detected in group III (p < 0.05). A positive correlation between the number of corpora lutea and the positive AMH signals in ovarian tissue was determined (r2 = 0.832, p < 0.05); however, only during mid-gestation (group II). Expression of AMHRII was in close co-localization with AMH and strong in the interstitial cells surrounding follicles undergoing atresia. AMHRII expression did not differ between pregnant groups but was higher compared to estrus cats (p ˂ 0.05). We conclude that AMH and AMHRII expression in the feline ovary is comparable to other species. The high serum AMH concentration and ovarian AMHRII expression between day 30 and 50 of gestation are probably related to ovarian activity and follicular atresia.

Feline breeding and pregnancy management: What is normal and when to intervene

Practical relevance:

Cats are common pets worldwide. Successful breeding of cats starts with the selection of suitable breeding animals, and care should be taken to avoid inbreeding. Keeping cats in smaller groups reduces stress and facilitates management.

Clinical challenges:

Breeding cats is challenging in many ways. Group housing is a common scenario, and care should be taken not to have groups that are too large, because of the risk of stress and infectious diseases. Feline pregnancy and parturition both vary in length, which is one reason why it may be challenging to diagnose dystocia. In queens with pyometra, a vaginal discharge may not be evident due to their meticulous cleaning habits.

Audience:

This review is aimed at clinicians in small animal practice, especially those in contact with cat breeders.

Patient group:

Reproductive emergencies occur in both intentionally and unintentionally bred cats, and more often in young or middle-aged queens. Pyometra tends to be a disease of older queens.

Evidence base:

Evidence is poor for many conditions in the breeding queen, and information is extrapolated from the dog or based on case reports and case series.

Central nervous system development of cats (Felis catus L. 1758)

The morphological similarities of vertebrates' embryonic development are used as a criterion for choosing animal models that can be used in biomedical research. This study describes the embryonic and fetal development of the domestic cat's central nervous system from 15 days after conception until birth. In total, fifty-seven samples of embryos and fetuses were carefully dissected and analyzed microscopically. The closure of the neural tube was observed between 14-15th days of gestation. The differentiation of the primordial cerebral vesicles was observed from the 17th day of gestation. On the 19th day of gestation, the formation of the choroid plexus began, and on the 20th day of gestation, the brain and brainstem were well-identified macroscopically. On the 24th day of gestation, four layers of cells from the cerebral cortex were described, and on the 60th day, six layers of cells were present. The cerebellar cortex had the three classic cortical layers at this stage. The morphological aspects of embryonic and fetal development in cats were very similar to the stages of development of the human nervous system. As such, this study provided relevant information that highlights the domestic cat as an animal model option for preclinical research on infectious and non-infectious neurological diseases in humans.

Ultrasonography of the normal reproductive tract of the female domestic cat

The objective of this study was (1) to describe the US appearance and obtain reference values for the uterus and ovaries in nongravid and gravid queens with histologically confirmed reproductive tracts without disorders, (2) to provide US measurements of the reproductive tract compared to gross macroscopic and water-bath post-OVH US measurements in nongravid queens, and (3) to describe the sonographic appearance of the female reproductive tract during the different histopathologic phases of the reproductive cycle in nongravid and gravid queens. Ninety-three queens from a "trap, neuter, return" program were included in this study. Sonographic evaluation of the reproductive tract was performed in all queens, and measurements of the corpus uteri, uterine horns, and ovaries were recorded. Following OVH, macroscopic measurements were obtained, and a water-bath US evaluation of these tissues and measurements was recorded. Samples from the corpus uteri and both the uterine horns and ovaries were collected for histopathologic examination after all measurements had been recorded. Seventy-two reproductive tracts met the inclusion criteria by having a histopathologically confirmed normal reproductive tract. Sixty-three queens were nonpregnant and 9 were pregnant. The ovaries and uterus were sonographically visible in all queens regardless of reproductive status. The ovaries were ovoid in shape, and the uterus appeared as a tubular structure with distinct wall layers (serosa and indistinct myometrium and myometrium, or serosa, myometrium, and endometrium), with variable echogenicity of the inner layers. The layering of the uterine wall, observed during the second half of pregnancy, was described. Ovarian follicles were visible in 66/72 (92%) cats. However, the CL was only visible in 40/72 (55%) cats. The reference values of the left ovarian length, right ovarian length, uterine horn diameter, and uterine body are 7.1-13.9, 7.3-13.6, 1-5.8, and 1.5-5.3 mm, respectively, in a nongravid uterus. The uterine wall thickness during pregnancy varied from 2.4 to 6.8 mm. There was a significant positive correlation between US measurements obtained in vivo and those obtained macroscopically and in a water bath post-OVH. The body weight, follicular size, sonographic visibility of the uterine wall layering, the histopathologic luteal phase, and the active/inactive status on histopathology had a significant effect on the uterine measurements (p < 0.05). It was not possible to describe the exact US features of the reproductive tract during the different histopathologic phases. In conclusion, ultrasonographic reference values for the normal female reproductive tract in cats were determined. The results of this study indicated that the ovaries and uterus were visible in cats regardless of reproductive status.

Gestational Aging and Determination of Parturition Date in the Bitch and Queen Using Ultrasonography and Radiography

This article provides a complete understanding of how radiography and ultrasound imaging can be used to determine gestational age when inadequate breeding data are available. Formulas for calculation of gestational age using both fetal and extrafetal structures are presented. Ultrasonographic descriptions of organ development and their use in determining gestational age are discussed. This information may be used to monitor the health and development of the fetuses and may be useful when the need to plan an elective or emergency Cesarean section occurs. Ultrasound imaging to assess fetal stress, viability, placental health and to sex fetuses is also described.

Determination of gestational time and prediction of parturition in dogs and cats: an update

Accurate prediction of delivery date in canine and feline allows a better management of parturition, reducing the loss of neonates. This review evaluates the most common methods adopted to accurately predict the day of delivery: determination of ovulation and hormonal assays, first appearance of embryonic/foetal structures using ultrasound or radiography, echographic measurement of extra-foetal and foetal structures, or evaluation of foetal flux and heart rate. Determination of ovulation and hormonal assays at the time of breeding and close to pregnancy term is widely used to predict parturition in dogs (Concannon et al. American Journal of Veterinary Research 44, 1983, 1819; Hayer et al. Journal of Reproduction and Fertility, Suppl. 47, 1993, 93; Hase et al. Journal of Veterinary Medical Science, 62, 2000, 243; Kutzler et al. Theriogenology, 60, 2003a, 1187). In cats, some studies have been carried out, but no hormonal parameters for accurate prediction of parturition have been described so far (Buff et al. Journal of Reproduction and Fertility, Suppl. 57, 2001, 187; De Haas van Dorsser et al. Biology of Reproduction, 74, 2006, 1090; DiGangi et al. Journal of the American Veterinary Medical Association, 237, 2010, 1267; Dehnhard et al. Theriogenology, 77, 2012, 1088). Many studies suggested that gestational timing can be obtained by observation using ultrasound or radiography of specific structures in relation to the time of appearance during gestation (Concannon and Rendano American Journal of Veterinary Research, 44, 1983, 1506; Rendano et al. Veterinary Radiology, 25, 1984, 132; Shille and Gontarek Journal of the American Veterinary Medical Association, 187, 1985, 1021; Davidson et al. Veterinary Radiology, 27, 1986, 109; England et al. Journal of Small Animal Practice, 31, 1990, 324; Yeager et al. American Journal of Veterinary Research, 53, 1992, 342; Zambelli et al. Theriogenology, 57, 2002a, 1981; Zambelli et al. Journal of Feline Medicine and Surgery, 4, 2002b, 95; Zambelli and Prati 2006; Lopate Theriogenology, 70, 2008, 397; Davidson and Baker Topics in Companion Animal Medicine, 24, 2009, 55). Ultrasonographic measurement of extra-foetal and foetal structures is a common and accurate method for the prediction of parturition day during pregnancy, when specific formulae are used depending on the ultrasonographic parameter, the species and, in canines, the size of the bitch (Shille and Gontarek Journal of the American Veterinary Medical Association, 187, 1985, 1021; England et al. Journal of Small Animal Practice, 31, 1990, 324; Luvoni and Grioni Journal of Small Animal Practice, 41, 2000, 292; Luvoni and Beccaglia Reproduction in Domestic Animals, 41, 2006, 27; Lopate Theriogenology, 70, 2008, 397; Michel et al. Reproduction in Domestic Animals, 46, 2011, 926; Beccaglia and Luvoni Reproduction in Domestic Animals, 47, 194, 2012). Recent studies demonstrated that in dogs, the imminence of parturition could be predicted by evaluating foetal flux and foetal heart rate by ultrasound (Gil et al. Theriogenology, 82, 2014, 933; Giannico et al., Animal Reproduction Science, 154, 2015, 105). For an accurate prediction of parturition date, the combination of different methods is desirable.

Evaluation of feline uterine and umbilical arteries blood flow in a pharmacologically induced abnormal gestation model

The aim of this study was to describe resistance index (RI) and systolic/diastolic ratio (S/D ratio) of uterine and umbilical arteries in an experimental model of abnormal pregnancy in felids. On days 30 to 35 (32 ± 2.9) after mating, 20 domestic short-hair pregnant queens were randomly assigned to one of the following treatment groups: a treated group (TG; n = 8), which received 10 mg/kg of aglepristone subcutaneously twice, 24 hours apart, and a control nontreated group (CG; n = 12). M-mode and Doppler ultrasonographic evaluations were performed at the initiation of the treatment (Day 0) and then every other day during 8 days. In both groups, uterine and umbilical arteries were evaluated by Doppler ultrasound, whereas fetal heart rate was assessed by M-mode ultrasound. Resistance index of uterine artery augmented in TG from Day 2 onward, conversely it decreased in CG (P < 0.01). On Day 8, RI values were 0.64 ± 0.05 vs 0.37 ± 0.01 for TG and CG, respectively. Additionally, S/D ratio of the same artery presented an increase in TG, whereas this ratio diminished in CG (P < 0.01). On Day 8, this parameter showed values of 2.98 ± 0.4 vs 1.62 ± 0.06 for TG and CG, respectively. Resistance index of umbilical artery remained almost unchanged in TG from Day 6 onward, whereas it progressively decreased in CG throughout the course of the study (P < 0.05). On Day 8, RI were 0.89 ± 0.04 and 0.82 ± 0.01, for TG and CG, respectively. Furthermore, on Day 8, S/D ratio of umbilical artery progressively diminished in CG but not in TG (P < 0.01), being 14.7 ± 9.1 vs 5.9 ± 0.3 for TG and CG, respectively. Fetal heart rate was higher in TG than in CG (P < 0.05). Group differences in Doppler parameters appeared on Day 2, when the other clinical or ultrasonographic signs were still absent. It is concluded that blood flow of the uterine and umbilical arteries differed between these normal and abnormal gestations predicting an adverse obstetric outcome.

Intra- and inter-observer variability in ultrasonographical measurements of the uterus and ovaries in healthy, non-pregnant queens

Objectives

We aimed to (1) evaluate how frequently the uterus and ovaries of healthy, non-pregnant queens are visible; (2) describe their appearance; (3) take their measurements; and (4) determine intra- and inter-observer variabilities in their measurements. We hypothesised that, using a high-frequency linear probe, the uterus and ovaries could be ultrasonographically visualised during any period of the sexual cycle and with any level of operator expertise.

Methods

Eight queens were enrolled in the study and the ultrasonographical appearance of their uterus and ovaries assessed with a high-frequency linear probe of 15–19 MHz. The diameter of the uterine horns, body and cervix in transverse and longitudinal sections, and the length of the ovaries were recorded. Three observers of different expertise level participated in the study, and the differences between the separate measurements made per queen were evaluated.

Results

The ovaries and the entire uterus were visualised in every queen. The ovaries were ovoid structures with submillimetric follicles during anoestrus and additional larger follicles depending on the stage of the cycle. An ovarian pattern suggesting cortex and medulla was observed in half the cases. In the uterus, the serosa was a thin hyperechoic outer rim, and layering was observed in half the cases. The cervix was difficult to identify. The intra- and inter-observer variabilities in the uterine horns and the ovaries were minimal (coefficient of variation [CV] 1.4–4.1%) compared with the differences within the queens (CV 10.9–43.4%). The longitudinal and transverse measurements of the horns and the uterine body were the same.

Conclusions and relevance

The ovaries and uterine horns in queens are accessible ultrasonographically at any stage of their cycle, and can be measured with low intra- and inter-observer variabilities.

Early pregnancy diagnosis and monitoring in the queen using ultrasonography with a 12.5 MHz probe

Eleven pregnancies in six queens were monitored daily from day 7 to day 28, corresponding to the end of the embryonic period, using ultrasonography with a 12.5 MHz probe. The first mating was considered as the presumed start of gestation, as has been described to be the case in 92.3% of pregnancies. The embryonic vesicles were identified on day 11, while the embryo appeared on day 15 or 16. The stage of pregnancy could be evaluated approximately by measuring the length of the embryonic vesicle or the crown–rump length of the embryo from days 11 and 17, respectively, up until the end of the embryonic phase of gestation. The visualisation of certain organs could also be used to date gestation; for example, the limbs, neural tube and stomach were visible from days 19, 20 and 26, respectively. The 12.5 MHz probe did not enable the diagnosis of gestation to be performed any earlier than with 7.5 and 10 MHz probes. However, there was a significant difference in comparison with a 5 MHz probe.

Morphometric analysis of fetal development of Cavia porcellus (Linnaeus, 1758) by ultrasonography--pilot study

Measurements on the growth process and placental development of the embryo and fetuses of Cavia porcellus were carried out using ultrasonography. Embryo, fetus, and placenta were monitored from Day 15 after mating day to the end of gestation. Based on linear and quadratic regressions, the following morphometric analysis showed a good indicator of the gestational age: placental diameter, biparietal diameter, renal length, and crown rump. The embryonic cardiac beat was first detected at an average of 22.5 days. The placental diameter showed constant increase from beginning of gestation then remained to term and presented a quadratic correlation with gestational age (r(2) = 0.89). Mean placental diameter at the end of pregnancy was 3.5 ± 0.23 cm. By Day 30, it was possible to measure biparietal diameter, which followed a linear pattern of increase up to the end of gestation (r(2) = 0.95). Mean biparietal diameter in the end of pregnancy was 1.94 ± 0.03 cm. Kidneys were firstly observed on Day 35 as hyperechoic structures without the distinction of medullar and cortical layers, thus the regression model equation between kidney length and gestational age presents a quadratic relationship (r(2) = 0.7). The crown rump presented a simple linear growth, starting from 15 days of gestation, displaying a high correlation with the gestational age (r(2) = 0.9). The offspring were born after an average gestation of 61.3 days. In this study, we conclude that biparietal diameter, placental diameter, and crown rump are adequate predictive parameters of gestational age in guinea pigs because they present high correlation index.

Feline Reproduction

Audience Many veterinarians are closely involved with pedigree cat breeding and have become familiar with the unique characteristics of feline reproduction and breeding management. However, even veterinarians who do not have involvement with the pedigree cat fancy require a basic knowledge of the reproductive problems that are most likely to be encountered in working with non-breeding pet cats as well as stray and feral cats.

Clinical challenges This article reviews reproductive problems and challenges in both sexes — namely, ovarian remnant syndrome, mammary fibroadenomatous hyperplasia, congenital anomalies of the reproductive tract and pregnancy diagnosis in the queen, and cryptorchidism and low libido in the tom.

Evidence base Feline reproduction has not received the amount of investigation and attention that has been directed at canine reproduction. The result is that less data is available both for description of normal reproduction and for management of common problems. This article reviews most of the available evidence for the conditions discussed. Efforts should focus on making information more readily available to the practitioner and expanding the knowledge base in this important area of feline medicine.

Ultrasonography for pregnancy diagnosis and evaluation in queens

In the present paper, we describe the clinical utility of ultrasonography for diagnosing and evaluating pregnancy in domestic cats. Ultrasonography is a non-invasive technique that permits an accurate diagnosis of pregnancy and allows serial evaluation of the developing embryo/fetus and the extrafetal structures. The first ultrasonographic indication of pregnancy is a gestational chamber seen on day 10 after mating as a small circular anechoic structure. From day 30, it is possible to recognize different fetal organs, and between 38 and 43 days, the gender of the fetus can be determined. Measurements obtained during the second half of gestation can be used to determine fetal age and calculations can then be made that may more accurately predict the time of parturition. Further studies are needed in the queen to determine the applicability of the echo-Doppler technique used routinely in human obstetric medicine. This type of ultrasonography could potentially provide useful information about fetal health and the maturity of the placenta.

Correlation between fetal age and ultrasonographic measurements during the second half of pregnancy in domestic cats (Felis catus)

We ultrasonographically evaluated the prenatal development in cats, from Day 30 to the end of pregnancy, subjecting a group of pregnant cats (n = 8) to daily ultrasonographic examinations. The ultrasonographic images allowed us to measure the diameter of the fetal abdomen, the biparietal diameter of the fetal skull and the diameter of the fetal stomach. A correlation between these measurements and gestational age was found with a linear, parabolic and exponential regression analysis. From Days 38 to 43 after breeding we also performed fetal gender determination by evaluating the external genitalia. All queens successfully carried their pregnancies to term. This study compiled useful new data in order to clinically monitor the normal course of pregnancy in cats and to determine gestational age.