A critical review of current methods for induction of parturition in the mare.

The efficacy and safety of oxytocin, dexamethasone and prostaglandin, used alone or in combination as inducing agents, are discussed. It is contended that insufficient evidence exists to support the routine application of any of these methods in practice. Oxytocin has been the most widely used and it is claimed by some to be free from side effects. However, the synthetic prostaglandin analogue, fluprostenol, seems to pose the least risk to the foetus and dexamethasone appears to be either ineffective, or too dangerous to use at all. The main indications for induced foaling are managerial convenience or for research and teaching purposes. There are few clinical indications, although ventral rupture and cases of prolonged gestation have been mentioned by various workers. It is considered that foetal maturity is the pre-requisite before a decision to induce should be made in practice, and 3 criteria are essential: 1) a gestational length of greater than 320 days, 2) substantial mammary development, 3) the presence of colostrum in the mammae.