In view of this author's position as Editor (EVJ), this paper was processed independently for peer review outside of the EVJ offices by a senior scientist.
Effects of maternally administered Depot ACTH1–24 on fetal maturation and the timing of parturition in the mare
Article first published online: 5 JAN 2010
2000 EVJ Ltd
Equine Veterinary Journal
Volume 32, Issue 6, pages 489–496, November 2000
How to Cite
OUSEY, J. C., ROSSDALE, P. D., PALMER, L., GRAINGER, L. and HOUGHTON, E. (2000), Effects of maternally administered Depot ACTH1–24 on fetal maturation and the timing of parturition in the mare. Equine Veterinary Journal, 32: 489–496. doi: 10.2746/042516400777584622
- Issue published online: 5 JAN 2010
- Article first published online: 5 JAN 2010
The aims of this study were to ascertain 1) whether fetal maturation could be induced precociously by maternal administration with adrenocorticotrophic hormone (ACTH) and 2) whether maturation could be achieved without significant risk to mare or fetus. Twenty-two mares received either 1 mg (low dose, LD, n = 6) or 4 or 5 mg (higher dose, HD, n = 16) synthetic Depot ACTH1–24 at 300, 301 and 302 days gestation. Because, during the course of the study, ACTH appeared to have a greaterinfluence on mares mated during the later part of the breeding season, the HD group were divided retrospectively into those mated before (HDE, n = 6), or after (HDL, n = 10), 1st July. All LD mares were mated before 1st July. Control injections were not performed but gestational data were compared retrospectively with 64 untreated, spontaneously foaling pony mares mated between May and October.
Plasma progestagen and cortisol concentrations increased significantly (P<0.05) following ACTH administration in all groups, but progestagens were higher and cortisol elevated for longer in HD mares. ACTH stimulated mammary development and milk electrolyte changes in HD mares. Mean ± s.e. gestation period (days) was significantly (P<0.01) shorter in HDLmares (318 ± 1.8) compared with LD (335 ± 3.7), HDE (340 ± 4.3) and untreated mares mated after 1st July (327 ± 1.3). All foals were mature except 2 HDLfoals which were stillborn. HDL foals had a higher MCV and lower mean bodyweight, indicating they were delivered before full term. In conclusion, maternal ACTH administration appears to accelerate fetal maturation and delivery in pony mares given high doses and mated late in the breeding season.
Further work is required to establish the optimal gestational age and dosage for maternal ACTH administration before clinical recommendations can be given for this therapy.