Effects of fluprostenol administration in mares during late pregnancy.

The study examines the use of prostaglandin F analogue fluprostenol on pregnant mares, to stimulate labour towards the end of gestation. The results suggest that the drug’s effectiveness in inducing labour is inconsistent, and may have both physical and behavioural impacts on the animals.

Research Objectives and Methodology

• The primary goal of this research was to determine the ability of fluprostenol, an analogue of prostaglandin F, to induce labour in mare during the final 50 days of gestation.
• The researchers also studied the behavioural and endocrine changes brought about by the drug in both pregnant and non-pregnant animals, as well as in foals.
• The administration of fluprostenol was done intramuscularly in doses of either 250 or 500 micrograms.

Key Findings

• The drug was found to be ineffective in inducing labour before 320 days of gestation, and its impact thereafter was unpredictable.
• Out of the 12 mares that foaled 1 to 36 hours following the fluprostenol injection, eight delivered viable foals while four produced stillborn or premature ones.
• Eight of these deliveries could potentially be attributed to the action of fluprostenol, as they occurred between 1 to 6 hours of its administration.
• The remaining four deliveries happened 12 to 36 hours following the drug injection, casting doubt on the causal relationship between the two events.

Further Observations

• Mares delivering viable foals showed characteristic full-term milk samples in terms of calcium, sodium, and potassium levels.
• In contrast, mares delivering premature or stillborn foals showed an imbalanced calcium and sodium/potassium ratio in their pre-partum milk.
• All three groups of animals exhibited physical and behavioural changes following the administration of fluprostenol, such as sweating, increased respiration, and defecation.
• The observed changes were accompanied by elevated plasma cortisol and adrenocorticotrophic hormone concentrations during the two-hour sampling period, suggesting a centrally mediated response to the drug.

Conclusion

• The findings suggest that while fluprostenol has some capacity to induce labour in pregnant mares, its efficacy is not consistent and relies heavily on the timing of the gestation period.
• The drug also seems to provoke both physical and behavioural reactions in mares, warranting further exploration of these side effects to ensure the safety and wellbeing of the animals involved.