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Biomedical subjects

F E Dudan

Publications and source records attributed to F E Dudan.

5 recordsLinked to original sources
PubMed1998

The effects of intrafetal ACTH administration on the outcome of pregnancy in the mare.

Enhanced adrenocortical activity in the fetus is related to the onset of parturition in many species. The aim of this study was to determine the effect of injection of fetal ACTH on gestational length and fetal viability in the horse. Pony mares (n=23) were studied from 300 days gestation. Seven control mares (Group 1) received three consecutive intrafetal injections of sterile water, while fetuses of a further 16 mares received Depot ACTH1-24. These mares were either allowed to foal spontaneously (Group 2, n=4) or delivery was induced within 3 days of the last fetal injection (Group 3, n=7); 5 mares aborted within 48 h of intrafetal ACTH injection. Maternal plasma progestagen concentrations increased significantly (P<0.05) in Groups 2 and 3 mares following intrafetal ACTH injection, compared with Group 1 mares. All Group 1 mares delivered live foals at a median gestational age of 327 days (interquartile range, 323 334), except one that aborted 16 days after the last fetal injection. Gestational length was significantly (P<0.05) shortened in Group 2 mares (median 314 [312-314]) days compared with controls. Group 1 and Group 2 foals showed normal postnatal adaptive responses and endocrine (plasma cortisol/progestagens) patterns. Group 3 mares delivered live foals at 306 (306-308) days gestation except one that aborted. Their foals were less mature compared with Groups 1 and 2 foals. Eight ACTH-injected fetuses were meconium-stained at delivery, including four that were aborted. Eight mares had thickened placentae, including three that aborted. The data show that both precocious maturation of the equine fetus and a significant reduction in gestational length compared with controls may be achieved in pony mares by intrafetal ACTH injections. This is probably mediated via adrenal regulation of fetal maturation and production of maternal progestagens.

Adrenocorticotropic Hormone↗
PubMed1984

Effects of fluprostenol administration in mares during late pregnancy.

The effectiveness of the prostaglandin F analogue fluprostenol in inducing labour in the mare was examined by giving sequential injections over the last 50 days of gestation. The behavioural and endocrine changes elicited by the drug in pregnant and non-pregnant animals and in foals were also studied. Fluprostenol (250 or 500 micrograms intramuscularly) failed to induce labour before 320 days gestation; thereafter its effect was capricious. Twelve mares foaled 1 to 36 h after the last test; eight delivered normal, viable, apparently 'term' foals and four produced stillborn/premature animals. Eight of the deliveries (five term and three pre-term foals) could be ascribed to the action of fluprostenol because they occurred 1 to 6 h after its administration, at a time when spontaneous foaling would have been unlikely. The other four mares foaled between 12 and 36 h after the fluprostenol injection and it is therefore doubtful whether there was a causal relationship between the two events. In the mares which delivered viable foals the pre-partum milk samples were characteristic of full term samples with respect to calcium, sodium and potassium. Those which delivered premature/stillborn foals had low calcium and a high sodium/potassium ratio in the pre-partum milk. Behavioural changes (sweating, increased respiration, defaecation etc), which varied in intensity between tests and individuals, were seen in all three groups of animals following the administration of fluprostenol. These changes were accompanied by rises in plasma cortisol and adrenocorticotrophic hormone concentration during the 2 h sampling period, suggesting a centrally mediated response to the drug.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗
PubMed1984

Studies on equine prematurity 1: Methodology.

This paper describes the general management of mares and foals during the perinatal period and the methodology used in a collaborative research project on equine prematurity. Sixteen mares with dated pregnancies delivered 45 foals over three breeding seasons (1981 to 1983). In the majority, parturition was induced with oxytocin and/or fluprostenol; the remainder were allowed to foal spontaneously. Pre-colostral milk analysis provided a means of assessing the pre-foaling status of the mare. All were observed and monitored before, during and after parturition and the sampling protocol for both mare and newborn foal is discussed in detail. The foals were assessed for their degree of maturity at birth using behavioural, haematological, acid-base status and other criteria; they were then assigned to groups for further study and tests.

Animals↗
PubMed1984

Studies on equine prematurity 2: Post natal adrenocortical activity in relation to plasma adrenocorticotrophic hormone and catecholamine levels in term and premature foals.

Adrenocortical and medullary function was investigated during the immediate post natal period in premature and full term foals. High plasma cortisol concentrations were characteristic of the term foals in the first 2 h after birth and these were accompanied by significant arteriovenous differences in plasma cortisol across the umbilical circulation at birth, indicating enhanced adrenal activity before delivery. No such arteriovenous differences were detected in the premature group and post natal changes in plasma cortisol were minimal. The apparent inability of the premature foal adrenal to secrete cortisol was not due to the lack of endogenous adrenocorticotrophic hormone (ACTH) because high levels of this hormone were found immediately after birth in both groups of foals. Tests on the sensitivity of the foal adrenal to exogenous ACTH1-24 (0.125 mg intramuscularly [im]) showed that a maximum response to this hormone could be elicited in term foals on the day of birth. Subsequently basal cortisol levels and the response of the adrenal to ACTH1-24 declined. By contrast, only a slight response was observed following the same dose of ACTH1-24 in the premature group. Exposure to Depot ACTH1-24 over 24 h enhanced the basal secretion of cortisol in both premature and term foals but no consistent response to the same ACTH test dose could be elicited in the former. A wide range of total plasma catecholamine concentrations was observed in both groups of newborn foals. The highest values were seen in acidotic animals and there was a significant inverse relationship between blood pH and total plasma catecholamine level at delivery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenocorticotropic Hormone↗