Ultrasonic measurements of second and third trimester fetuses to predict gestational age and date of parturition in captive and wild spotted hyenas Crocuta crocuta

The accuracy of gestational age predicted from femur and humerus length in Saanen goats using ultrasonography

Serial transabdominal ultrasonographic scanning was performed to measure femur and humerus length of foetuses of Saanen goats to establish their gestational stage. Data were obtained from 38 goats that became pregnant after artificial insemination. Animals were restrained in a supine position on a special table designed for this purpose. Humerus and femur length were measured at weekly intervals starting from week 8 of gestation till the end of gestation. Real-time ultrasound scanner equipped with switchable frequency (5-7.5 MHz) micro convex probe was used in the present study. Humerus and femur length showed strong positive correlation with gestational age (r2 = 0.95). Measurements of humerus and femur of foetuses are useful indicators to predict gestational age at the 2nd and 3rd trimesters in Saanen goats. Measuring of only one bone length is quite enough. Incorporating of both measurements within a multiple regression equation did not improve predictive capacity of the bones. The results of the study were used to construct reference charts and gestational equations in Saanen goats utilizing humerus and femur measurements. In Sudan, this is the first study utilizing measurements of the femur and humerus and the first study comparing the length of the humerus and femur for predicting gestational age in Saanen goats.

The anti-androgen combination, flutamide plus finasteride, paradoxically suppressed LH and androgen concentrations in pregnant spotted hyenas, but not in males

The androgen receptor blocker flutamide and the 5α-reductase inhibitor finasteride have been used in a variety of species to investigate the ontogeny of sexual dimorphisms by treating pregnant females or neonates at critical periods of sexual differentiation. Likewise, we have used these drugs to study the profound masculinization of the external genitalia in female spotted hyenas. However, a potential pitfall of administering flutamide, either alone or in combination with finasteride, is that it maintains or even raises plasma concentrations of luteinizing hormone (LH) and testosterone (T), because negative feedback of the hypothalamic-pituitary-gonadal axis is disrupted. Contrary to expectations, when pregnant spotted hyenas were treated with flutamide and finasteride (F&F), the concentrations of T during late gestation were suppressed relative to values in untreated dams. Herein, we further investigate the paradoxical effects of F&F treatment on a battery of sex hormones in spotted hyenas. Beyond the effects on T, we found plasma concentrations of LH, estradiol, progesterone and androstenedione (A4) were also significantly lower in F&F-treated pregnant hyenas than in controls. Flutamide and finasteride did not have similar effects on LH, T, and A4 concentrations in male hyenas. The paradoxical effect of F&F treatment on LH and T concentrations in the maternal circulation suggests that negative feedback control of gonadotropin and androgen secretion may be modified in spotted hyenas during pregnancy.

Prediction of gestational age by transrectal ultrasonographic measurements in the mouflon (Ovis gmelini musimon)

Serial transrectal ultrasonographies were performed measuring different structures of mouflon (Ovis gmelini musimon) fetuses to establish their gestational age. Data were obtained from 14 mouflon ewes that became pregnant after estrous synchronization. From day 25 of gestation onward, the crown-rump length and the trunk diameter of the embryo were estimated. Later, when the fetal organs and structures could be distinguished, several measurements were done in the skull (occipito-snout length and biparietal and orbit diameters), the trunk (thoracic diameter and width of vertebrae), and the abdominal cavity (stomach and kidney longitudinal diameters); femur length was also determined. All fetal measurements were correlated with gestational age (P < 0.001), but the parameters showing the highest correlation with time (R2 up to 0.94) were the crown-rump and occipito-snout lengths and the thoracic and biparietal diameters. No significant differences were observed in pregnancies with one or two fetuses in the period studied.

The Ontogeny of the Urogenital System of the Spotted Hyena (Crocuta crocuta Erxleben)1

Studies were conducted to elucidate the importance of androgen-mediated induction of the extreme masculinization of the external genitalia in female spotted hyenas. Phallic size and shape; androgen receptor (AR) and alpha-actin expression; and sex-specific differences in phallic retractor musculature, erectile tissue, tunica albuginea, and urethra/urogenital sinus were examined in male and female fetuses from Day 30 of gestation to term. Similar outcomes were assessed in fetuses from dams treated with an AR blocker and a 5alpha-reductase inhibitor (antiandrogen treatment). Clitoral and penile development were already advanced at Day 30 of gestation and grossly indistinguishable between male and female fetuses throughout pregnancy. Sex-specific differences in internal phallic organization were evident at Gestational Day 45, coincident with AR expression and testicular differentiation. Antiandrogen treatment inhibited prostatic development in males and effectively feminized internal penile anatomy. We conclude that gross masculinization of phallic size and shape of male and female fetuses is androgen-independent, but that sexual dimorphism of internal phallic structure is dependent on fetal testicular androgens acting via AR in the relevant cells/tissues. Androgens secreted by the maternal ovaries and metabolized by the placenta do not appear to be involved in gross masculinization or in most of the sex differences in internal phallic structure.

Integrating ultrasonography within the reproductive management of the collared peccary (Tayassu tajacu)

Ultrasound imaging has been used to elucidate certain aspects of the reproductive biology of wild or endangered species. However, to our knowledge, this tool has not been used for reproductive monitoring of the collared peccary (Tayassu tajacu). In this study, real-time ultrasonography was used in 16 collared peccary females to diagnose early pregnancy status and predict gestational age. Based on the detection of an embryo, the earliest pregnancy diagnosis was made on Day 18 after mating, with the mean time needed for diagnosis being 22 days. Overall accuracies on Days 22, 26 and 28 were 56, 93, and 100%, respectively. On Days 26 and 28, all pregnancy and non-pregnancy diagnoses, respectively, were correct. The fetal measurements that best correlated with gestational age were crown-rump-length (CRL) and the length and diameter of the thorax. CRL was considered the most practical measurement because, contrary to thoracic fetometry, it could be determined when the embryo was first detected. Our findings revealed real-time ultrasound scanning to be a very accurate method for early pregnancy diagnosis and prediction of gestational age in the collared peccary.