Management of twin conceptuses by manual embryonic reduction: comparison of two techniques and three hormone treatments

• Published in: American journal of veterinary research Vol. 48; no. 11; pp. 1594 - 1599
• Main Authors: Pascoe, D.R, Pascoe, R.R, Hughes, J.P, Stabenfeldt, G.H, Kindahl, H
• Format: Journal Article
• Language: English
• Published: United States 01.11.1987
• Subjects: administration & dosage; analogs & derivatives; Animals; ANTI-INFLAMMATOIRE; anti-inflammatory agents; ANTIINFLAMMATORY AGENTS; ANTINFLAMATORIOS; Clonixin; Clonixin - administration & dosage; Clonixin - analogs & derivatives; Clonixin - pharmacology; conceptus; drug effects; Female; flunixin; flunixin meglumine; Horses; Horses - physiology; Injections, Intramuscular; Injections, Intravenous; JUMENT; MARES; mortality; Nicotinic Acids; Nicotinic Acids - pharmacology; pharmacology; physiology; placebos; POLIEMBRIONIA; POLYEMBRYONIE; POLYEMBRYONY; Pregnancy; Pregnancy, Animal; Pregnancy, Animal - drug effects; Pregnancy, Multiple; Pregnancy, Multiple - drug effects; PROGESTERONA; PROGESTERONE; Progesterone - administration & dosage; Progesterone - pharmacology; PROSTAGLANDINAS; PROSTAGLANDINE; PROSTAGLANDINS; rectum; sesame oil; sodium chloride; SUPERVIVENCIA; SURVIE; SURVIVAL; Twins; uterus; veterinary medicine; viability; YEGUA
• ISSN: 0002-9645; 1943-5681
• DOI: 10.2460/ajvr.1987.48.11.1594

One hundred mares carrying twin conceptuses between gestation days ( gd ) 12 and 30 were assigned to 4 groups. Group-1 mares (n = 20) were given a placebo (sterile saline solution, iv , and sesame oil, im ). Group-2 mares (n = 32) were given a single dose of progesterone (625 mg, im ) in sesame oil. Group-3 mares (n = 28) were given multiple progesterone treatments (625 mg, im ) at 6-day intervals until gd 42. Group-4 mares (n = 20) were given a single treatment of flunixin meglumine (500 mg, iv ) and progesterone (625 mg, im ). Each group was further assigned to equal subgroups A and B according to the age of the embryos. In subgroup A, with embryos at gd 12 to 16, embryonic vesicle rupture was performed after the selected conceptus was moved to the tip of a uterine horn. In subgroup B, with embryos at gd 17 to 30, embryonic vesicle rupture was performed on the selected conceptus in situ. An additional 6 mares carrying single conceptuses ( gd 12, 14, 16, 20, 25, and 30) were used as subjects for sham embryonic vesicle rupture. Both rupture techniques usually caused the release of prostaglandin ( pg )F 2α for up to 90 minutes. Amounts of pgf 2α were directly correlated with the pressure required to efffect embryonic vesicle rupture. Sham embryonic vesicle rupture attempts caused small pgf 2α releases after each manipulation, which rapidly returned to basal values. All 6 mares were still pregnant at gd 42. Flunixin meglumine inhibited pgf 2α release after embryonic vesicle rupture, regardless of the technique. Survival rates for the remaining conceptus were 100% for group 1A (10 of 10), 100% for group IB (10 of 10), 100% for group 2A (16 of 16), 94% for group 2B (15 of 16), 86% for group 3A (12 of 14), 93% for group 3B (13 of 14), 100% for group 4A (10 of 10), and 100% for group 4B (10 of 10). Thus, embryo removal can be accomplished in the mare without effect on the remaining embryo if the technique (embryonic vesicle per rectum) is done before gd 30. Administration of exogenous progesterone or flunixin meglumine was not essential for maintaining viability of the remaining conceptus.